1. Helwan University
Faculty of Science
Chemistry Department
Introduction of Biochemistry
Dr
Mohamed Mostafa Omran
1
2. Biochemistry is the study of life including cell biology, genetics,
immunology, microbiology, pharmacology, and physiology. Biochemical
processes are controlled genetically. Although it overlaps other disciplines,
including cell biology, genetics, immunology, microbiology, pharmacology,
and physiology.
Four major classes of biomolecules serve as building blocks for larger
macromolecules:
1. Carbohydrates: e.g. glucose, fructose, sucrose, mainly used as sources of
car energy.
2. Lipids: commonly known as fats
- organic compounds that are not very water soluble
- used as sources of cellular energy
- components of cell membranes
3. Amino Acids:
- 20 natural amino acids in total
- Used as building blocks for proteins
4. Nucleotides:
- 5 in total
- Used as building blocks for DNA and RNA precursors
5. Other:
- Vitamins: organic compounds necessary for proper growth and
development
- Heme: Organometallic compound containing iron; important for
transporting oxygen in your blood stream.
2
3. Carbohydrates
General Information:
1. Carbohydrates are the most abundant class of organic compounds found
in living organisms.
2. They originate as products of photosynthesis, an endothermic reductive
condensation of carbon dioxide requiring light energy and the pigment
chlorophyll.
n H2O + Energy
CnH2nOn + n O2
3. The formulas of many carbohydrates can be written as carbon hydrates,
Cn (H2O) n, hence their name.
4.
The carbohydrates are a major source of metabolic energy, both for
plants and for animals that depend on plants for food.
5.
Aside from the sugars and starches that meet this vital nutritional role,
carbohydrates also serve as a structural material (cellulose), a component of
the energy transport compound ATP, recognition sites on cell surfaces, and
one of three essential components of DNA and RNA.
6.
Carbohydrates are called saccharides or, if they are relatively small,
sugars.
A- Simple Sugars
1 Contain the elements carbon, hydrogen, and oxygen.
2 The name carbohydrate literally means water compounds of carbon.
3 The general formula for simple sugars is Cn(H2O)n.
4 This class of compounds is better described as Polyhydroxy aldehydes and
ketones.
5 The simplest carbohydrates are glyceraldehyde and dihydroxyacetone.
3
4. O
H
C
C
H
O
O
H H C C CH O
O 2
2 H
H
CH O
2 H
glyceraldehyde
dihydroxyacetone
A - Methods of Classification:
Several methods are used to classify carbohydrates.
1-One method of classification is based on whether the carbohydrate
can be broken down into smaller units.
Monosaccharides: simple sugars cannot be broken down into smaller units
by hydrolysis.
1. Disaccharides: can be broken down into two monosaccharide units.
2. Oligosaccharides: can be broken into three to six monosaccharide units.
3. Polysaccharides: composed of 7 or more monosaccharide units.
2-Another method is based on the number of carbons found in a simple
sugar.
If it has 3 carbons it is called a triose.
If it has 4 carbons it is called a tetrose.
If it has 5 carbons it is called a pentose.
If it has 6 carbons it is called a hexose.
3-Another method uses the kind of carbonyl group.
A- Aldose: A monosaccharide with an aldehyde group.
4
5. O
HC
H
C
OH
H
C
OH
CH2OH
erythrose
B- Ketose: A monosaccharide with a ketone group.
CH2OH
C
O
HO
C
H
H
C
OH
H
C
OH
CH2OH
fructose
Usually combine the carbonyl classification and the number classification
together.
H
O
C
CH2OH
H
O
C
H
C
OH
CH2OH
glyceraldehyde
aldotriose
OH
HO
H
C
C
H
H
C
H
C
C
O
HO
C
H
OH
H
C
OH
OH
H
C
OH
CH2OH
glucose
aldohexose
CH2OH
fructose
ketohexose
B-Stereoconfigurations of simple sugars
Carbohydrates contain many stereocenters. If the OH group is found
on the right side of the carbon chain, the sugar is designated as a D sugar
5
6. (i.e., the -OH at C5 of D-glucose is on the right in a Fischer projection). If
the OH group is found on the left side of the chain of carbons, the sugar is
designated as an L sugar (The L sugars are the mirror images of their D
counterparts). Sugars that differ only by the configuration around one C
atom are known as epimers of one another. e.g, D-glucose and D-mannose
are epimers with respect to C2.
The most common ketoses are those with their ketone function at C2.
The position of their carbonyl group gives ketoses one less asymmetric
center than their isomeric aldoses, so a ketohexose has only 23 = 8 possible
stereoisomers (4 D sugars and 4 L sugars).
H
H
C
C
O
H
OH
HO
CH 2OH
C
C
O
H
CH 2OH
D-glyceraldehyde
L-glyceraldehyde
D-aldotriose
L-aldotriose
6
7. B- Stereoconfigurations of simple sugars
CHO
H C OH
CH2OH
D-glyceraldehyde
CHO
CHO
H C OH
HO C H
H C OH
H C OH
CH2OH
CH2OH
D-erythrose
D-threose
CHO
HO C H
CHO
CHO
CHO
H C OH
H C OH
HO C H
H C OH
H C OH
HO C H
H C OH
H C OH
H C OH
H C OH
CH2OH
CH2OH
CH2OH
D-arabinose
D-ribose
CH2OH
D-lyxose
CHO
HO C H
HO C H
CHO
CHO
D-xylose
CHO
H C OH
H C OH
HO C H
H C OH
H C OH
HO C H
HO C H
HO C H
HO C H
H C OH HO C H
HO C H
CHO
CHO
HO C H
CHO
HO C H
H C OH
HO C H
CHO
H C OH
H C OH
HO C H
H C OH
H C OH
H C OH
H C OH
H C OH
H C OH
H C OH
H C OH
H C OH
H C OH
H C OH
H C OH
CH2OH
CH2OH
CH2OH
CH2OH
CH2OH
CH2OH
CH2OH
CH2OH
D-allose
D-tallose
D-galactose
D-mannose
D-glucose
D-altrose
7
D-idose
D-gulose
8. C H2O H
C
O
C H2O H
d ih y d r o x y a c e t o n e
C H2O H
C
O
C
H
OH
C H2O H
D -e r y th r u l o s e
C H2O H
C
HO
H
C H2O H
O
C
O
C
H
H
C
OH
OH
H
C
OH
C
C H2O H
D - r ib u lo s e
C H2O H
D - x y lu lo s e
C H2O H
C
HO
O
C
H
HO
C
H
H
C
OH
C H2O H
D -ta g a to s e
H
C
C H2O H
C H2O H
C
C H2O H
C
O
HO
OH
C
C
O
H
H
C
OH
C
OH
C
OH
O
HO
C
H
H
C
OH
H
H
C
OH
H
C
OH
H
C H2O H
D -fr u c to s e
C H2O H
D -s o r b o s e
C H2O H
D - p s ic o s e
Cyclic Structures: Five membered sugar rings are known as furanose rings.
H
C
O
H C OH
HO CH2
H
H C OH
H C OH
CH2OH
D-ribose
H
O
H
H
OH
-D-ribofuranose
8
H
+
OH
OH
HO CH2
OH
O
H
H
H
OH
OH
-D-ribofuranose
9. Six membered sugar rings are known as pyranose rings.
H
C
O
HO CH2
H OH
OH H
H C OH
HO C H
H C OH
HO
H C OH
CH2OH
+
OH
H OH
-D-glucopyranose
D-glucose
Carbohydrate Anomers:
HO CH2
H O OH
OH H
HO
H
H OH
-D-glucopyranose
Formation of either of the cyclic form has
created a new stereocenter. These stereoisomeric ring forms of
carbohydrates are called Anomers.
Anomers:
Anomers are carbohydrates that differ by the stereo-configuration of the
carbon involved in ring formation. (the carbonyl carbon, called the
anomeric
carbon,
becomes
a
chiral
center
with
two
possible
configurations.). The greek letters α and β are used to describe these
configurations about the ring forming carbon. The α anomer always has the
OH group oriented in a downward fashion on the anomeric carbon of a Dsugar. The β anomer always has the OH group oriented in an upward
fashion on the anomeric carbon of a D-sugar.
The two anomers of D-sugar have slightly different physical and
chemical properties, including different optical rotations The anomers freely
interconvert in aqueous solution, so at equilibrium, D-glucose is a mixture of
the β anomer (63.6%) and the α anomer (36.4%). The linear form is
normally present in only minute amounts.
9
10. Important Carbohydrates
Monosaccharides: composed of three to seven carbon atoms.
1- Glucose
1 The most abundant hexose in our diet.
2 The building block of complex carbohydrates.
3 Component of the disaccharides: sucrose, maltose and lactose.
4 Found in the polysaccharides: starch, cellulose and glycogen.
CHO
CH2OH
H C OH
H
HO C H
H C OH
O
H
OH H H,OH
OH
H
H C OH
CH2OH
OH
2. Galactose
Found in the disaccharide, lactose.Found in the cellular membranes of the
brain and nervous system. Galactose is the C-4 epimer of glucose.
CHO
CH2OH
H C OH
HO
HO C H
HO C H
O
H
OH H H,OH
H
H C OH
H
CH2OH
OH
3. Fructose
Sweetest of the carbohydrates. Component of the disaccharide sucrose.
Fructose is a keto sugar.
11
11. CHO
CH2OH
H C OH
HO
HO C H
O
H H,OH
H
HO C H
H
OH
OH
H
H C OH
CH2OH
Disaccharides: composed of 2 monosaccharide units.
1. Maltose - malt sugar. Used in cereals, candies and the brewing of
beverages.Composed of two D-glucose sugars joined by an α-1,4 linkage.
CH2OH
CH2OH
O H
H
H
OH
O OH
H
H
OH
H
H
O
OH
H
H
OH
H
OH
2. Lactose - milk sugar. Found in milk and milk products. Composed of
one galactose and one glucose unit joined by a β-1,4 linkage.
CH2OH
CH2OH
OH
H
OH
O
O OH
H
O
H
H
OH
H
H
H
H
H
OH
OH
3. Sucrose - table sugar. Product of sugar cane and sugar beets. Composed
of one glucose and one fructose unit. Linkage is at both anomeric carbons.
11
12. CH2OH
H
H
OH
OH
H
CH2OH
O
O H
H
H
OH
OH
H
H
O
OH
CH2OH
Polysaccharides: composed of many (more than 10) monosaccharide units.
classified as homopolysaccharides(if they consist of one type of
monosaccharide) or heteropolysaccharides ( consist of more than one type
of monosaccharide). Polysaccharides in contrast to proteins and nucleic
acids, form branched as well as linear polymers. This is because glycosidic
linkages can be made to any of the hydroxyl groups of a monosaccharide.
1- Cellulose: Major structural material of plant cells. Consists of many
glucose units joined by β-1,4 linkages. ( a linear polymer of up to 15,000 Dglucose residues linked by β (1-4) glycosidic bonds).
2. Starch: Storage form of glucose found in rice wheat, potatoes, grains and
cereals. Consists of many glucose units joined by α-1,4 linkages. Maltose is
the disaccharide starting material. is deposited in the chloroplasts of plant
cells as insoluble granules composed of α-amylose and
amylopectin. α-Amylose is a linear polymer of several thousand glucose
residues linked by α
12
13. 3. Glycogen: Animal starch. Storage form of glucose found in the liver and
muscle of animals. Contains many highly branched glucose units.
1 Joined by α-1,4 linkages and branched by α-1,6 linkages.
4. Chitin: is the principal structural component of the exoskeletons of
invertebrates such as crustaceans, insects, and spiders and is also present in
the cell walls of most fungi and many algae. Chitin is a homopolymer of
-linked Nacetyl- D-glucosamine residues.
13
14. Conclusion
1- Carbohydrates are wide group of bio molecules that represents the
first row of energy sources in our bodies.
2- Carbohydrates are carbon hydrate molecules that can be simple or
multiple from two (disaccharide) or more (poly saccharides)
monomeric units of (monosaccharides).
3- Carbohydrates are stereochemical active molecules.
4- general formula of simple sugar is Cn (H2O)n like glucose C6(H2O)6.
5- Disaccharides like succrose, poly saccharides like starch which is
linear or branched polymers.
14
15. Amino Acids
Amino Acids are the building units of proteins. Proteins are polymers of
amino acids linked together by what is called ― Peptide bond‖ (see latter).
There are about 300 amino acids occur in nature. Only 20 of them occur in
proteins.
Structure of amino acids:
Each amino acid has 4 different groups attached to α- carbon (which is
C-atom next to COOH). So the common amino acids are known as α-amino
acids, These 4 groups are: amino group, COOH group, hydrogen atom and
side Chain (R). The 20 standard amino acids differ in the structures of their
side chains (R groups).
Amino Acids Are Dipolar Ions
At physiological PH (7.4), -COOH gp is dissociated forming a
negatively charged carboxylate ion (COO-) and amino gp is protonated
forming positively charged ion (NH3+) forming Zwitter ion (dipolar ions :
act as both an acid and a base). Amino acids, like other ionic compounds, are
more soluble in polar solvents than in nonpolar solvents.
15
16. Peptide Bonds Link Amino Acids
Amino acids can be polymerized to form chains. This process can be
represented as a condensation reaction (bond formation with the
elimination of a water molecule). The resulting CO-NH linkage, an amide
linkage, is known as a peptide bond. Polymers composed of two, three, a
few (3–10), and many amino acid units are known, respectively, as
dipeptides,
tripeptides,
oligopeptides,
and
polypeptides.
These
substances, however, are often referred to simply as peptides. After they are
incorporated into a peptide, the individual amino acids (the monomeric
units) are referred to as amino acid residues. Polypeptides are linear
polymers rather than branched chains; that is, each amino acid residue
participates in two peptide bonds and is linked to its neighbors in a head-totail fashion. The residues at the two ends of the polypeptide each participate
in just one peptide bond. The residue with a free amino group is called the
amino terminus or N-terminus. The residue with a free carboxylate group
(at the right) is called the carboxyl terminus or C-terminus.
Classification of amino acids
I- Chemical classification: According to number of COOH and NH2
groups i.e. according to net charge on amino acid.
A- Monobasic, monocarboxylic amino acids i.e. neutral or uncharged
(glycine, alanine, valine)
16
17. B- Basic amino acids:
Contain two or more NH2 groups or nitrogen atoms that act as base i.e. can
bind proton. At physiological pH, basic amino acids will be positively
charged. e.g.
a- Lysine
b- Arginine: contains guanido group
c- Histidine: is an example on basic heterocyclic amino acids
C- Acidic Amino acids: at physiological pH will carry negative charge. e.g.
Aspartic acid (aspartate) and Glutamic acid (glutamate).
see structures in hand out. Aspargine and Glutamine: They are amide
forms of aspartate and glutamate in which side chain COOH groups are
amidated. They are classified as neutral amino acids.
17
18. II- Classification according to polarity of side chain (R):
The amino acid side chains in globular proteins are spatially distributed
according to their polarities:
A- Polar amino acids: in which R contains polar hydrophilic group so can
forms hydrogen bond with H2O.
In those amino acids, R may contain:
1- OH group: as in serine, threonine and tyrosine
2- SH group: as in cysteine
3- amide group: as in glutamine and aspargine.
4- NH2 group or nitrogen act as a base (basic amino acids): as lysine,
arginine and histidine.
5- COOH group ( acidic amino acids): as aspartic and glutamic .
-The charged polar residues Arg, His, Lys, Asp, and Glu are usually located
on the surface of a protein in contact with the aqueous solvent. This is
18
19. because immersing an ion in the virtually anhydrous interior of a protein is
energetically unfavorable.
-The uncharged polar groups Ser, Thr, Asn, Gln, and Tyr are usually on the
protein surface but also occur in the interior of the molecule. When buried in
the protein, these residues are almost always hydrogen bonded to other
groups, the formation of a hydrogen bond neutralizes their polarity.
B- Non polar amino acids:
R is alkyl hydrophobic group which can’t enter in hydrogen bond
formation. 9 amino acids are non polar (glycine, alanine, valine, leucine,
isoleucine, phenyl alanine, tryptophan, proline and methionine).
The nonpolar residues Val, Leu, Ile, Met, and Phe occur mostly in the
interior of a protein, out of contact with the aqueous solvent. The
hydrophobic effects that promote this distribution are largely responsible for
the three-dimensional structure of native proteins.
19
20. III- Nutritional classification:
1- Essential amino acids: These amino acids can’t be formed in the body
and so, it is essential to be taken in diet. Their deficiency affects growth,
health and protein synthesis.
2- Semiessential amino acids: These are formed in the body but not in
sufficient amount for body requirements especially in children.
3- Non essential amino acids: These are the rest of amino acids that are
formed in the body in amount enough for adults and children. They are
the remaining 10 amino acids.
IV- Metabolic classification: according to metabolic or degradation
products of amino acids they may be:
1- Ketogenic amino acids: which give ketone bodies.Lysine and Leucine
are the only pure ketogenic amino acids.
2- Mixed ketogenic and glucogenic amino acids: which give both
ketonbodies and glucose.These are: isoleucine, phenyl alanine, tyrosine
and tryptophan.
21
21. 3- Glucogenic amino acids: Which give glucose. They include the rest of
amino acids. These amino acids by catabolism yields products that enter
in glycogen and glucose formation.
Properties of Amino Acid
A. Physical properties:
1. Solubility: most of the amino acids are soluble in water and insoluble in
inorganic solvent:
2. Melting point: amino acids are generally melt at higher temperature ,
often above 200°C
3. Taste: amino acids may be sweet (Gly, Ala, Val), tasteless (Leu) or bitter
(Arg, ILe).Monosodium Glutamate (Ajinomoto) is used as flavouring agent
in food industry, chinese foood to increase taste and flavour.
Zwitterions or dipolar ion: The name Zwitter derived from the
German word which mean hybrid. Zwitter ion is a hybrid molecule
containing positive and negative ionic group. The amino acids rarely exists
in a neutral form with free carboxylic (-COOH ) and free amino
(-NH2)
groups. In strongly acidic pH the amino acid are positively charged, while
in strongly alkaline pH it is negatively charged. Each amino acid has a
characteristics pH at which it carries both positive and negative charge and
Exist as Zwitterions.
Isoelectric pH: pH at which amino acids exist as the zwitterion
(neutral) and carries no net charge. Thus molecule is electrically neutral.
The pl value can be calculated by taking the average pKa values
corresponding to the ionizable groups. For example leucine has two
ionizable groups, and its pl value can be calculated as follows.
21
22. B. Chemical properties
3 Reaction due to –COOH group
1. Amino acid form salts (-COONa) with base, and Ester (-COOR) with
alcohol.
2. Decarboxylation: Amino acid undergo deacarboxylation to produce
amines: this reaction assumes significance in the living cell due to the
formation of many biologically important amine. These include histamine,
tyramine, γ-amino butyric acid from the amino acid histidine, tyrosine and
glutamate respectively.
3. Reaction with ammonia: the carboxyl group of dicarboxylic amino acid
reacts with NH3 to form amide.
Aspartic acid + NH3
Aspargine
22
24. 4. Reaction due to NH2
The amino acid behave as bases and combine with acids to form salts.
Reaction with ninhydrine: the α- Amino acidreact with ninhydrine to form a
purple , blue or pink color complex (Ruhemann’s purple)
Amino acid + ninhydrine
keto acid+NH3+ CO2+ Hydrindantin
Hydrindantin+ NH3+Ninhydrine
Ruhemann’s purple
5. Colour reaction
6. Transamination
7. Oxidative deamination: Ninhydrine can react with imino acids as proline
and hydroxy proline but gives yellow color.
3- Reactions due to side chain (R):
1- Millon reaction: for tyrosine gives red colored mass
2- Rosenheim reaction: for trptophan and gives violet ring.
3- Pauly reaction: for imidazole ring of histidine: gives yellow to reddish
product
4- Sakagushi test: for guanido group of arginine andgives red color.
5- Lead sulfide test (sulfur test): for sulfur containing amino
acids as
cysteine give brown color.
Peptides and Proteins
20 amino acids are commonly found in protein. These 20 amino acids
are linked together through ―peptide bond forming peptides and proteins
(what’s the difference). The chains containing less than 50 amino acids are
called ―peptides‖ while those containing greater than 50 amino acids are
called ―proteins‖.
24
25. Peptide bond formation:
α-carboxyl group of one amino acid (with side chain R1) forms a
covalent peptide bond with α-amino group of another amino acid ( with the
side chain R2) by removal of a molecule of water. The result is Dipeptide (
i.e. Two amino acids linked by one peptide bond). By the same way, the
dipeptide can then forms a second peptide bond with a third amino acid
(with side chain R3) to give Tripeptide. Repetition of this process generates
a polypeptide or protein of specific amino acid sequence.
Peptide bond formation:
Each polypeptide chain starts on the left side by free amino group of the
first amino acid enter in chain formation . It is termed (N- terminus).
- Each polypeptide chain ends on the right side by free COOH group of the
last amino acid and termed (C-terminus).
25
26. Examples on Peptides:
1- Dipeptide (tow amino acids joined by one peptide bond):
Example: Aspartame which acts as sweetening agent being used in
replacement of cane sugar. It is composed of aspartic acid and phenyl
alanine.
2- Tripeptides: 3 amino acids linked by two peptide bonds. Example:
glutathione which is formed from 3 amino acids: glutamic acid, cysteine
and glycine. It helps in absorption of amino acids, protects against hemolysis
of RBC by breaking H2O2 which causes cell damage.
3- Octapeptides: 8 amino acids, for examples: two hormones; oxytocine
and vasopressin (ADH).
4- Polypeptides: 10- 50 amino acids: e.g. Insulin hormone
Protein structure:
There are four levels of protein structure (primary, secondary, tertiary
and quaternary).
1. Primary structure: The primary structure of a protein is its linear
sequence of amino acids and the location of covalent linkages such as
disulfide bonds between amino acids. Lysozyme, an enzyme that attacks
bacteria, consists of a polypeptide chain of 129 amino acids. The precise
primary structure of a protein is determined by inherited genetic information.
At one end is an amino acid with a free amino group the (the N-terminus)
and at the other is an amino acid with a free carboxyl group the (the Cterminus).
26
27. High orders of Protein structure
A functional protein is not just a polypeptide chain, but one or more
polypeptides precisely twisted, folded and coiled into a molecule of unique
shape (conformation). This conformation is essential for some protein
function e.g. Enables a protein to recognize and bind specifically to another
molecule e.g. hormone/receptor; enzyme/substrate and antibody/antigen.
27
28. 2- Secondary structure: areas of folding or coiling within a protein;
Results from hydrogen bond formation between hydrogen of –NH group of
peptide bond and the carbonyl oxygen of another peptide bond. According
to H-bonding there are two main forms of secondary structure:
α-helix: It is a spiral structure resulting from hydrogen bonding between one
peptide bond and the fourth one
β-sheets: is another form of secondary structure in which two or more
polypeptides (or segments of the same peptide chain) are linked together by
hydrogen bond between H- of NH- of one chain and carbonyl oxygen of
adjacent chain (or segment).
28
29. Hydrogen bonding in α-helix: In the α-helix CO of the one amino acid
residue forms H-bond with NH of the forth one.
Supersecondary structure or Motifs: occurs by combining secondary
structure. The combination may be: α-helix- turn- α-helix- turn…..etc
Or: β-sheet -turn- β-sheet-turn………etc
Or: α-helix- turn- β-sheet-turn- α-helix
Turn (or bend): is short segment of polypeptides (3-4 amino acids) that
connects successive secondary structures.
e.g. β-turn: is small polypeptide that connects successive strands of βsheets.
29
30. 3. Tertiary structure is determined by a variety of non-covalent
interactions (bond formation) among R groups and between R groups and
the polypeptide backbone forming three-dimensional structure of a protein
a.
The weak interactions include:
Hydrogen bonds among polar side chains. Ionic bonds between
charged R groups (basic and acidic amino acid). Hydrophobic interactions
among hydrophobic (nonpolar) R groups.
b. Strong covalent bonds include disulfide bridges, that form between
the sulfhydryl groups (SH) of cysteine monomers, stabilize the
structure.
4. Quaternary structure: results from the aggregation (combination) of
two or more polypeptide subunits held together by non-covalent interaction
like H-bonds, ionic or hydrophobic interactions.
Examples on protein
having quaternary structure:
Insulin: two polypeptide chains (dimeric)
Collagen is a fibrous protein of three polypeptides (trimeric) that are
supercoiled like a rope. This provides the structural strength for their role in
connective tissue.
31
31. Hemoglobin is a globular protein with four polypeptide chains (tetrameric
Classification of proteins
I- Simple proteins: i.e. on hydrolysis gives only amino acids
Examples:
1- Albumin and globulins: present in egg, milk and blood. They are
proteins of high biological value i.e. contain all essential amino acids
and easily digested.
31
32. Types of globulins:
α1 globulin: e.g. antitrypsin.
α2 globulin: e.g. hepatoglobin: protein that binds hemoglobin to prevent its
excretion by the kidney
β-globulin: e.g. transferrin: protein that transport iron
γ-globulins e.g Immunoglobulins (antibodies) : responsible for immunity.
Conjugated proteins: i.e. On hydrolysis, give protein part and non protein
part and subclassified into:
1- Phosphoproteins: These are proteins conjugated with phosphate group.
Phosphorus is attached to oh group of serine or threonine. e.g. Casein of
milk and vitellin of yolk.
2- Lipoproteins:
These are proteins conjugated with lipids.
Functions:
a- help lipids to transport in blood. b- Enter in cell membrane
structure helping lipid soluble substances to pass through cell membranes.
3- Glycoproteins: proteins conjugated with sugar (carbohydrate)
e.g. Mucin
Some hormones such as erythropoeitin
Present in cell membrane structure
Blood groups.
4- Nucleoproteins: These are basic proteins ( e.g. histones) conjugated with
nucleic acid (DNA or RNA).
e.g. a- chromosomes: are proteins conjugated with DNA
b- Ribosomes: are proteins conjugated with RNA
5- Metalloproteins: These are proteins conjugated with metal like iron,
copper, zinc.
32
33. a- Iron-containing proteins:Iron may present in heme such as in
- hemoglobin (Hb), myoglobin (protein of
skeletal muscles and
cardiacmuscle), cytochromes, catalase, peroxidases (destroy H2O2). Iron
may be present in free state (not in heme) as in three forms:
Ferritin: main store of iron in the body, present in liver, spleen and bone
marrow.
Hemosidrin: another iron store.
Transferrin: is the iron carrier protein in plasma.
b- Copper containing proteins:
e.g. - Ceruloplasmin which oxidizes ferrous ions into ferric ions.
- Oxidase enzymes such as cytochrome oxidase.
c- Zn containing proteins: e.g. Insulin and carbonic anhydrase
d- Mg containing proteins:e.g. Kinases and phosphatases.
6-Chromoproteins: These are proteins conjugated with pigment. e.g.
- All proteins containing heme (Hb, myoglobin)
- Melanoprotein:e.g proteins of hair or iris which contain melanin.
Derived proteins
Produced from hydrolysis of simple proteins.
e.g. - Gelatin: from hydrolysis of collagen
- Peptone: from hydrolysis of albumin
33
34. Conclusion
1. Amino Acids are the building units of proteins
2. Each amino acid has 4 different groups attached to α- carbon
are: amino group, COOH group, hydrogen atom and side Chain (R).
3. Amino Acids are classified chemically to neutral or uncharged e.g: (
glycine, alanine, valine). Basic amino acids: Lysine
- Acidic Amino acids :-Aspargine and Glutamine
4. Classified according to polarity of side chain (R) to:( Polar amino
acids- Non polar amino acids)
5. Nutritional classification (Essential amino acids, Semi essential amino
acids -Non essential amino acids).
6. Metabolic classification (Ketogenic amino acids, mixed ketogenic and
glucogenic amino acids and Glucogenic amino acids)
7. amino acids are bonded to each other by peptide bonds forming
peptides or proteins
8. Proteins structures are primary, secondary, tertiary and quaternary.
9. proteins can be simple or conjugated (containing non protein part )
34
35. Lipids
1 Lipids are diverse in form and are defined by solubility in non-polar
solvents (and insolubility in water)
2 Lipids are used for efficient energy storage, as structural components
of cell membranes, as chemical messengers and as fat-soluble
vitamins with a variety of functions
3 We consume many lipids from a variety of plant and animal sources
4 Our cells can also biosynthesize most lipids.
Classification of Lipids
1. Simple lipids: Esters of fatty acids with various alcohols.
a. Fats: Esters of saturated fatty acids with glycerol (animal sources).
b. Oils: Esters of unsaturated fatty acids with glycerol (plant sources).
c. Waxes: Esters of fatty acids with higher molecular weight monohydric
alcohols.
2. Complex lipids: Esters of fatty acids containing groups in addition to an
alcohol and a fatty acid.
a. Phospholipids: They frequently have nitrogen-containing bases and
other substituents, eg, in glycerophospholipids the alcohol is glycerol and
in sphingophospholipids the alcohol is sphingosine.
b. Glycolipids (glycosphingolipids): Lipids containing a fatty acid,
sphingosine, and carbohydrate.
c. Other complex lipids: Lipids such as sulfolipids and aminolipids.
Lipoproteins may also be placed in this category.
3) Precursor and derived lipids: These include steroids (cholesterol),
lipid-soluble vitamins, and hormones.
35
36. Types of Lipids
1 Following is a summary of the types of lipids we will study and their
general structures:
Fatty Acids
1 The simplest lipids are the fatty acids, which rarely exist alone in
nature, but instead are usually a component of more complex lipids
2 Fatty acids are carboxylic acids with a long hydrocarbon chain
attached
3 Although the acid end is polar, the nonpolar hydrocarbon tail makes
fatty acids insoluble (or sparingly soluble) in water
36
37. 4 Fatty acids can be classified by how many double bonds are present in
the hydrocarbon tail:
- Saturated fatty acids have only single bonds
- Monounsaturated fatty acids have one double bond
- Polyunsaturated fatty acids have two or more double bonds
Structures and Melting Points of Saturated Fatty Acids
37
38. Physical Properties of Saturated Fatty Acids
Saturated fatty acids have:
1 Molecules that fit closely together in a regular pattern
2 Strong attractions (dispersion forces) between fatty acid chains
3 High melting points that makes them solids at room temperature.
Structures and Melting Points of Unsaturated Fatty Acids
38
39. Physical Properties of Unsaturated Fatty Acids
Unsaturated fatty acids have:
1 Nonlinear chains that do not allow molecules to pack closely
2 Weak attractions (dispersion forces) between fatty acid chains
3 Low melting points and so are liquids at room
temperature
39
40. Triglycerides
Triglycerides (also called Triacylglycerols) are tri-fatty acid esters of
glycerol. Triglycerides are the major form of fatty acid storage in
plants and animals. Triglycerides can be classified as fats or oils.
- fats are solid at room temperature and most come from animals
- oils are usually liquid at room temperature and come from plants
(palm and coconut oils are liquids at room temperature). Triacylglycerols
function as energy reservoirs in animals and are therefore their most
abundant class of lipids because they are not components of cellular
membranes.
41
41. Olive Oil
Olive oil contains mostly triolein, which has three oleic acids. Oleic acid,
a monounsaturated fatty acid, is a component of all fats and oils, but is
especially abundant in olive and peanut oils. Some studies have
shown that oleic acid may raise HDL (―good cholesterol‖) levels
while also lowering LDL (―bad cholesterol‖) levels
41
42. Olestra: a Fat Substitute
Olestra is: used in foods as an artificial fat. Sucrose linked by ester
bonds to several long-chain fatty chains. Not broken down in the
intestinal tract. Olestra inhibits the absorbtion of fat-soluble vitamins
(A, D, E and K) and carotenoids. There are many reports of problems
such as diarrhea and abdominal cramps with olestra use, but the
manufacturers claim there’s no proof
Reaction of fatty acids
1. Hydrogenation
2. Oxidation
3. Hydrolysis
1. Hydrogenation of Unsaturated Oils
Hydrogenation converts alkenes to alkanes. So, hydrogenation of
unsaturated oils produces saturated fats. Hydrogenation is typically
carried out by bubbling H2 gas through the heated oil, in the presence
of a metal catalyst (such as nickel or platinum). Unsaturated oils are
usually only partially hydrogenated, so that the product is not
completely saturated, giving a soft semisolid fat such as margarine
42
43. +3H2
O
Pt
O
CH2 O C (CH2)7CH CH(CH2)7CH3
O
CH2
O
C
O
(CH2)16CH3
O
C
O
(CH2)16CH3
CH
O C (CH2)7CH CH(CH2)7CH3
O
CH
CH2
O C (CH2)7CH CH(CH2)7CH3
CH2
O
C
(CH2)16CH3
Cis and Trans Unsaturated Fatty Acids
1. Natural unsaturated fatty acids have cis double bonds
2. When unsaturated vegetable oils are hydrogenated to form more saturated
oils (as in margarine), some of the cis fatty acids are isomerized to trans
fatty acids.
3.Trans fatty acids are much more linear than cis fatty acids, so their melting
points are higher and studies have shown that trans fats may act similarly
to saturated fats and could contribute to heart disease and some cancers.
4.Due to new requirements for including amounts of trans fats on food labels,
many companies are developing hydrogenation methods that do not
produce trans fats
2. Oxidation of Unsaturated Oils
Fats and oils can become rancid in two ways:
43
44. - bacterial ester hydrolysis (next slide)
- air oxidation of alkenes
Oxidation of fatty acid alkenes involves cleavage of the double bonds to
form short-chain carboxylic acids. These oxidation products are foul-tasting
and smell horrible
O
OH
O2 or O3
O
O
O
+
OH
HO
OH
Hydrolysis of Fats and Oils
1. Fats and oils contain ester groups which can be hydrolyzed with aqueous
acid, aqueous base (saponification) or enzymes
2. The hydrolysis products are glycerol and three fatty acids
3. When triglycerides containing short-chain fatty acids are hydrolyzed the
carboxylic acid products (such as butanoic and hexanoic acids) are foulsmelling and foul-tasting (rancid)
O
H 2C
H 2C
O
C
O
(CH2)14CH3
HC
O
C
O
(CH2)14CH3
H 2C
O
C
(CH2)14CH3
OH
O
H3O+
44
HC
OH
H 2C
or
lipase
OH
+
3 HO
C
(CH2)14CH3
45. Saponification
When a triglycerides is hydrolyzed with a strong base the process is
called saponification. The products of saponification are glycerol and fatty
acid salts (soap). NaOH is used with saturated fats to produce hard soaps.
KOH is used with unsaturated fats to produce softer, more liquid soaps
O
H 2C
O
C
O
(CH2)14CH3
H 2C
OH
O
NaOH
HC
H 2C
O
O
C
O
(CH2)14CH3
C
(CH2)14CH3
HC
OH
+ 3 Na
O
C
(CH2)14CH3
(Soap)
H 2C
OH
Cholesterol
Cholesterol is soft, fat-like, waxy substance. Bloodstream and cells
needed it for cell membranes and hormones and to make vitamin D.
comes from 2 sources:
– Body produces it (mostly genetic) in liver (1000 mg day)
– Food sources (animal products not from plant sources such as meats,
poultry, fish, eggs, butter, whole milk, and cheese) (100 – 500 mg day)
– Foods with trans fats or saturated fats may cause the body to produce
more cholesterol
45
46. Cholesterol
Must be transported through blood. Carriers are called lipoproteins
– Low-density lipoprotein (LDL)
– High-density lipoprotein (HDL)
Lipoprotein = protein + fat
– LDL, more fat, less protein
– HDL, more protein, less fat
LDL vs. HDL
LDL = ―bad‖. Too much can clog arteries by forming plaque
Atherosclerosis can cause heart attack or stroke.
LDL vs. HDL
HDL = ―good‖. Tends to carry cholesterol away from arteries and back to
liver. May also remove excess cholesterol from plaque in arteries, slows
buildup
Triglycerides
Form of fat. Also made in body (body fat stored as triglyceride) and from
food. Help transport dietary fat, metabolism. Trigger liver to make more
cholesterol, rising LDL and total cholesterol
Synthesis of vitamin D
46
47. Steroids
Steroids constitute an important class of biological compounds. Steroids
are usually found in association with fat. They are derivatives of
cholesterol that is formed of steroid ring or nucleus. Biologically
important groups of substances, which contain this ring, are: Sterols,
Adrenal cortical hormones, Male and female sex hormones, Vitamin
D
group, Bile acids, Cardiac glycosides.
Bile acids: They are produced from oxidation of cholesterol in the liver
producing cholic and chenodeoxycholic acids that are conjugated with
glycine or taurine to produce glycocholic, glycochenodeoxycholic,
taurocholic and taurochenodeoxycholic acids. They react with sodium or
potassium to produce sodium or potassium bile salts.
Their function is as follows: Emulsification of lipids during digestion. Help
in digestion of the other foodstuffs. Activation of pancreatic lipase. Help
digestion and absorption of fat-soluble vitamins. Solubilizing cholesterol in
bile and prevent gall stone formation. Intestinal antiseptic that prevent
putrefaction
Conclusion
1- Lipids are esters of fatty acids, alcohols, sometimes additional
groups.
2- lipids are storage forms of energy for living organisms
3- lipids are classified to simple (esters of fatty acids and alcohols)
and complex (contains additional groups e.g. protein part)
4- fatty acids are the building unites of lipids which can be saturated
or unsaturated
5- Cholesterol is soft, fat-like, waxy substance. Cells needed it for
cell membranes and hormones and to make vitamin D.
47
48. 6- Good cholesterol (HDL), bad cholesterol (LDL) is very important
types of cholesterol used in detection of fat content abnormalities.
7- Triglycerides are Forms of fat made in body and from food. Help
transport dietary fat, metabolism. Trigger liver to make more
cholesterol, rising LDL and total cholesterol
8- Steroids are derivatives of cholesterol that is formed of steroid
ring or nucleus e.g:Adrenal cortical hormones.
9- Bile acids are produced from oxidation of cholesterol in the liver,
make Emulsification of lipids during digestion. Help in digestion
of the other foodstuffs.
48
49. NUCLEOTIDES
There are eight common varieties of nucleotides, each composed of a
nitrogenous base linked to a sugar to which at least one phosphate group is
also attached. The bases of nucleotides are planar, aromatic, heterocyclic
molecules that are structural derivatives of either purine or pyrimidine
(although they are not synthesized in vivo from either of these organic
compounds).
The most common purines are adenine (A) and guanine (G), and the
major pyrimidines are cytosine (C), uracil (U), and thymine (T).
The purines form bonds to a five-carbon sugar (a pentose) via their N9
atoms, whereas pyrimidines do so through their N1 atoms. In
ribonucleotides, the pentose is ribose, while in deoxyribonucleotides (or just
deoxynucleotides), the sugar is 2’-deoxyribose (i.e., the carbon at position 2’
lacks a hydroxyl group). Note that the primed numbers refer to the atoms of
the pentose; unprimed numbers refer to the atoms of the nitrogenous base.
In a ribonucleotide or a deoxyribonucleotide, one or more phosphate groups
are bonded to atom C3’ or atom C5’ of the pentose to form a 3’-nucleotide
or a 5’-nucleotide, respectively When the phosphate group is absent, the
compound is known as a nucleoside. A 5’-nucleotide can therefore be called
a nucleoside-5’-phosphate. Nucleotides most commonly contain one to three
phosphate groups at the C5’ position and are called nucleoside
monophosphates, diphosphates, and triphosphates.
49
50. The structures, names, and abbreviations of the common bases,
nucleosides, and nucleotides Ribonucleotides are components of RNA
(ribonucleic acid), whereas deoxynucleotides are components of DNA
(deoxyribonucleic acid). Adenine, guanine, and cytosine occur in both
ribonucleotides and deoxynucleotides (accounting for six of the eight
common nucleotides), but uracil primarily occurs in ribonucleotides and
thymine occurs in deoxynucleotides. Free nucleotides, which are anionic, are
almost always associated with the counterion Mg2+ in cells.
Nucleic Acids Are Polymers of Nucleotides
The nucleic acids are chains of nucleotides whose phosphates bridge
the 3’ and 5’ positions of neighboring ribose units. The phosphate of these
polynucleotides is acidic, so at physiological pH, nucleic acids are
polyanions. The linkage between individual nucleotides is known as a
phosphodiester bond, so named because the phosphate is esterified to two
ribose units. Each nucleotide that has been incorporated into the
polynucleotide is known as a nucleotide residue. The terminal residue whose
C5’ is not linked to another nucleotide is called the 5’ end, and the terminal
residue whose C3’ is not linked to another nucleotide is called the 3’ end. By
convention, the sequence of nucleotide residues in a nucleic acid is written,
left to right, from the 5’ end to the 3’ end. The properties of a polymer such
51
51. as a nucleic acid may be very different from the properties of the individual
units, or monomers.
DNA Forms a Double Helix (Watson–Crick model)
The Watson–Crick model of DNA has the following major features:
1. Two polynucleotide chains wind around a common axis to form a double
helix.
2. The two strands of DNA are antiparallel (run in opposite directions), but
Each forms aright-handed helix.
3. The bases is the core of the helix and sugar–phosphate chains are the
periphery.
4. Each base is hydrogen bonded to a base in the opposite strand to form a
planar base pair.
The Watson ــــCrick structure can accommodate only two types of
base pairs. Each adenine residue must pair with a thymine residue and vice
versa, and each guanine residue must pair with a cytosine residue and vice
versa. These hydrogen-bonding interactions, a phenomenon known as
complementary base pairing, result in the specific association of the two
hains of the double helix.
51
52. RNA Is a Single-Stranded Nucleic Acid
RNA occurs primarily as single strands, which usually form compact
structures rather than loose extended chains (double-stranded RNA is the
hereditary material of certain viruses). An RNA strand which is identical to a
DNA strand except for the presence of 2’-OH groups and the substitution of
uracil for thymine can base-pair with a complementary strand of RNA or
DNA. As expected, A pairs with U (or T in DNA), and G with C.
52
54. Enzymes
Function of Enzymes
Biological catalysts made up of proteins. Enzymes speed up the rate
of chemical reactions in the body; both breaking down (e.g.: starch into
maltose) and building up reactions. (e.g: amino acids into proteins).
Enzymes lower the activation energy required to start a chemical reaction
Characteristics of Enzymes
Enzymes are highly specific in action. Enzymes remain chemically
unchanged
at the end of the reaction. Enzymes are required in minute
amounts.
Nomenclature of Enzymes
In most cases, enzyme names end in –ase
The common name for a hydrolase is derived from the substrate
– Urea: remove -a, replace with -ase = urease
– Lactose: remove -ose, replace with -ase = lactase
Other enzymes are named for the substrate and the reaction catalyzed
– Lactate dehydrogenase
– Pyruvate decarboxylase
Some names are historical - no direct relationship to substrate or reaction
type
– Catalase, pepsin, chymotrypsin and trypsin
Nomenclature and Classification
Enzymes are often classified by placing them in categories according to the
reactions that they catalyze:
Classification
Type of Reaction Catalyzed
1. Oxidoreductases
Oxidation–reduction reactions
54
55. 2. Transferases
Transfer of functional groups
3. Hydrolases
Hydrolysis reactions
4. Lyases
Group elimination to form double bonds
5. Isomerases
Isomerization
6. Ligases
Bond formation coupled with ATP hydrolysis
Classification of Enzymes
Oxidoreductases catalyze redox reactions
– Reductases
– Oxidases
2.Transferases: transfer a group from one molecule to another
– Transaminases catalyze transfer of an amino group
– Kinases transfer a phosphate group
3. Hydrolases cleave bonds by adding water
– Phosphatases
– Peptidases
– Lipases
55
56. 4. Lyases catalyze removal of groups to form double bonds or the reverse
break double bonds.eg Decarboxylases and synthases
5. Isomerases catalyze intramolecular rearrangements
– Epimerases
– Mutases
1. Ligases catalyze a reaction:
in which a C-C, C-S, C-O, or C-N bond is made or broken
56
57. Mode of Action
Substrate fits in the enzyme active site, just like a key fits into a lock.
An enzyme-substrate complex is formed. Chemical reactions occur at the
active site and products are formed.
1. Lock and Key Enzyme Model: In the lock-and-key model, the enzyme
is assumed to be the lock and the substrate the key. The enzyme and
substrate are made to fit exactly. This model fails to take into account
proteins conformational changes to accommodate a substrate molecule
2. Induced Fit Enzyme Model
The induced-fit model of enzyme action assumes that the enzyme active site
is more a flexible pocket whose conformation changes to accommodate the
substrate molecule
57
58. Specificity of the Enzyme-Substrate Complex
For enzyme and substrate to react, surfaces of each must be complementary.
Enzyme specificity: the ability of an enzyme to bind only one, or a very few,
substrates thereby catalyzing only a single reaction. Compare these 2
reactions: Urease is very specific or has a high degree of specificity.
Classes of Enzyme Specificity
Absolute: enzyme reacts with only one substrate
Group: enzyme catalyzes reaction involving any molecules with the same
functional group
Linkage: enzyme catalyzes the formation or break up of only certain
category or type of bond
Stereochemical: enzyme recognizes only one of two enantiomers
Cofactors and Coenzymes
Active enzyme / Holoenzyme:
– Polypeptide portion of enzyme (apoenzyme)
– Nonprotein prosthetic group (cofactor)
Cofactors are bound to the enzyme for it to maintain the correct
configuration of the active site
– Metal ions
– Organic compounds
– Organometallic compounds
58
59. Coenzymes
A coenzyme is required by some enzymes
– An organic molecule bound to the enzyme by weak interactions
/ Hydrogen bonds
– Most coenzymes carry electrons or small groups
– Many have modified vitamins in their structure
59
60. Factors affecting Enzyme Activity
1. Temperature
Low temperatures, at 0C cause low Kinetic Energy of enzymes and
substrates. No/very few enzyme-substrate complexes are formed. Enzymes
are inactivated. at 20 0C Increasing the temperature will lead to the increase
in kinetic energy of enzyme and substrate molecules. Enzyme and substrate
molecules move with increasing speed and collide more frequently with
each other. This increases the rate of enzyme-substrate complex formation
This increases the rate of enzyme-substrate complex formation and product
formation then rate of reaction increases. As the temperature continues to
61
61. increase, the rate of enzyme activity also increases until the optimal
temperature is reached. Optimal temperature is the temperature at which the
enzyme works best. Rate of product formation is highest. Beyond Optimal
Temperatures, at high temperatures (>60°C), weak bonds within the enzyme
molecule are broken. Enzyme loses its shape and its active site.Loss of shape
leads to a loss of function. Enzyme is said to have denatured. Denaturation
is the change in 3D structure of an enzyme or any other protein caused by
heat or chemicals such as acids or alkali, causing it to lose its function.
Different enzymes denature at different temperatures. Most enzymes
denature at temperatures higher than 60°C. However, there are some
enzymes that stay active even at high temperatures like 80°C (Enzymes in
the bacteria Thermus aquaticus).
2. Effect of pH on enzyme activity
Enzyme works best within a narrow pH range. Each enzyme works
best at particular pH, known as its optimum pH level. At extreme pH levels,
enzymes lose their shape and function and become denatured.
61
62. 3. Effect of substrate concentration on enzyme activity
As substrate concentration increases, the rate of reaction increases (at
constant enzyme concentration). The enzyme eventually becomes saturated
giving maximum activity.
Uses of Enzymes in Medicine
Diagnostic enzyme levels altered with disease
Liver :Aspartate aminotransferase (AST), alanine aminotransferase (ALT)
alkaline phosphatase (ALP), gamma glutamyl tranferase (GGT)
Heart attack: Lactate dehydrogenase, Creatine phosphate, AST
62
63. Pancreatitis: Amylase, lipase
Analytical reagents: Enzyme used to measure another substance eg. Urea
converted to NH3 via urease.
CONCLUSION
1. Enzymes Biological highly specific catalysts made up of proteins
which speed up the rate of chemical reactions in the body.
2. Common name of an enzyme = substrate or reaction or both +ase.
3. Enzymes act according to Lock and Key Model also Induced Fit
Enzyme Model.
4. Enzyme activity affected by temperature, pH and enzyme
substrate concentration.
5. Diagnostic enzyme levels altered with disease.
63
64. Vitamins
Vitamins are made up of carbon, hydrogen and oxygen. Vitamins are
called micronutrients because they are needed in only very small quantities.
They all have chemicals names but they are usually referred to by letters.
Main functions
Vitamins are essential to the body:
1. To maintain health
2. To help prevent deficiency diseases such as Beriberi (weakened muscles,
heart, nerves and digestive system) and rickets (softening of the bones)
3. To regulate the repair of body cells
4. To help combat the ageing process
5. To help to process carbohydrates and release energy in the body
Vitamins are Two main categories
1. Water soluble Vitamins ( B, C)
2. Fat Soluble (A, D, E, K)
Water soluble: Cannot be stored in body - regular supply needed. Excess is
excreted in urine. No danger of toxic levels. Unstable to heat and light, leach
into cooking liquids.
Fat Soluble: Can be stored in body - regular supply not needed. Can
accumulate to toxic levels if large amounts ingested. Fairly stable at normal
cooking temperatures
Vitamin A found in two forms; Retinol and Beta-Carotene
Retinol: Named because of its concern with retina of eye, only found in
animal foods
Beta-Carotene: plant sources, present with chlorophyll in plants, converted
to Vitamin A in gut wall.
64
65. Functions: Regulates growth, promotes healthy skin,
maintenance of
healthy tissues, helps eye adapt to dim light.
Sources: Retinol - Cod liver oil, Liver, Dairy products, Herrings, Egg yolk
Beta-Carotene:
Dark green leafy, vegetables, Broccoli, Carrots, Deep
orange, fruits and vegetables
Effects of deficiency
• Retarded growth, malformed bones, long term-may lead to night
blindness, susceptibility to infection, excess beta-carotene may lead
to liver and bone damage
Vitamin D -Calciferols
Functions: Absorption and laying down of calcium and phosphorous in
bones and teeth. Regulates calcium balance between bones and blood,
Prevents rickets
Sources: Sunlight conversion, Fish liver oils, Dairy products, Oily fish,
Margarine
Effects of deficiency
1. Rickets in children and osteomalacia in adults (Conditions where bones
are soft and cannot take weight of body).
2.Osteoporosis (Bones become light, less dense and prone to fractures)
3. Dental caries
Vitamin E - Tocopherol
Functions:
1. Protects tissues against damage
2. Promotes normal growth and development
3. Helps in normal red blood cell formation
Sources: Pure vegetable oils, Wheat, wholemeal bread, Cereals, egg yolk,
nuts, sunflower seeds.
65
66. Effects of deficiency
Deficiency is very rare but it could affect the central nervous system
Vitamin K - Napthoquinone
Functions: Needed for blood clotting, which means it helps wounds heal
properly.There is increasing evidence that vitamin K is also needed to help
build strong bones.
Sources: Green leafy Vegetable, vegetable oil, cereals.
Effects of deficiency
Deficiency is very rare but individuals with liver damage and new born
infants are at a higher risk
Vitamin B1 - Thiamin
Functions: Essential for release of energy from carbohydrates. Necessary
for appetite and good health. Needed for normal functioning of nervous
system
Sources: Meat, Oatmeal, Breakfast cereals, Wheat, Fortified white flour
Milk, Eggs, vegetables
Deficiency:
1. Fatigue, depression, irritability
2. Beri-beri - disease of nervous system
Vitamin B2 -Riboflavin
Functions
1. Metabolism of carbohydrates, proteins and fats
2. Growth, repair, development of body tissues - healthy skin, eyes and
tongue
3. The principal growth promoting factor in the vitamin B complex
Sources: Offal, Milk, Cheese, Eggs, Yeast extracts, Green Vegetables
66
67. Deficiency
1. Loss of appetite
2. Swollen tongue, cracked lips, eye infection,
Vitamin B3 -Niacin
Functions
1. Metabolism of carbohydrates, proteins and fats
2. Needed for normal functioning of nervous system
Sources: Meat, Offal, Yeast extracts, Yeast, Bran, wheat, flour
Some pulses, dried fruit
Deficiency
1. Fatigue, depression, irritability
2. Beri-beri - disease of nervous system
Vitamin B9 -Folic Acid
Functions
1. Red blood cell formation
2. Development of brain, spinal cord and skeleton in foetus
3. Reduces risk of neural tube defects e.g. spina bifida
4. May play role preventing heart attacks, strokes and cancer
Sources:
fortified cereals, green leafy vegetables, potatoes, bread, milk, wheat
Deficiency
1. Fatigue in mild cases
2. Anaemia in severe cases
3. Neural tube defects
Important to take folic acid prior to conception and vital during first 3
months pregnancy
67
68. Vitamin C -Ascorbic Acid
Functions
1. Critical to immune system. 2. Formation of connective tissue, collagen
Helps absorption of iron. 3. Prevents scurvy. 4. Promotes healing of wounds
and healthy blood vessels.5. Acts as antioxidant, protects cholesterol
Sources: Rosehips, blackcurrants, green peppers, kiwi, citrus, fruits,
strawberries, spinach, cabbage, broccoli
Deficiency
1. Weakening of connective tissue
2. Susceptibility to infection
3. Incomplete iron absorption
4. Delayed healing of wounds
5. Prevent scurvy - pale skin with spots, bleeding, soft gums.
Conclusion
1. Vitamins are very important organic biomolecules which can be water
soluble or fat soluble
2. Water soluble: Cannot be stored in body, Unstable to heat and light, leach
into cooking liquids.e.g: ( B, C)
3. Fat Soluble: Can be stored in body. Fairly stable at normal cooking
temperatures.eg; (A, D, E, K)
4. Each type of vitamins have it's own importance and is needed daily for
healthy body.
68
69. MINERALS
Our body requires mineral elements for a variety of functions. They are also
known as micronutrients. Unlike vitamins, which are organic substances
minerals are inorganic and are found in rocks and soil. Vegetables absorb
minerals as they grow, while animals digest it through their diet. Minerals
can be divided into two groups those needed in larger quantities (major
minerals) and those only required in tiny amounts (trace elements).
Trace Minerals - are iron, zinc and iodine.
Major Minerals - are sodium, potassium, calcium and phosphorus.
Minerals have 4 major functions: Body building – teeth and bones. Control
of body processes, especially the nervous system. Essential part of body
fluids and cells. Form part of enzymes and other proteins necessary for the
release of energy
Iron
Functions: Production of haemoglobin in red blood cells to carry oxygen in
the blood
Deficiency: Anaemia,
Sources: Red meat, Kidney, Liver, Eggs, Bread, Green veg
Calcium
Functions: Teeth and bones, Blood clotting, Nerve and muscle contraction.
Heart regulation.
Deficiency: Stunted growth can cause rickets, osteoporosis.
Sources: Dairy products, fortified white bread, oily fish, green veg, nuts and
seeds, citrus fruits.
Phosphorus
Functions: Bones and teeth with calcium.Muscle contraction
Deficiency: Rarely deficient but could cause tiredness and depression
69
70. Sources: Dairy products, Nuts, Meat, Fish, foods rich in calcium
Sodium
Functions: Maintains water balance in the body and controls body
temperature, helps you sweat when body temp rises.
Deficiency: Deficiency is highly unlikely
Sources: Cheese, Bacon, smoked meats, Fish, processed foods, table salt.
Government advice says on average you should be eating no more than 6g of
salt a day.
Potassium
Functions: Muscle contraction and in maintaining fluid. It is necessary for
the building of muscle and for normal body growth.
Deficiency: Dry skin, acne, Muscle spasms
Sources: Banana, Celery, Turnips
Zinc
Functions: Everything from acne to diabetes. Aids the immune system.
Needed for the senses of smell and taste.
Deficiency: Dry skin, acne, Muscle spasms
Sources: Meat (lamb), Oats, Eggs, Nuts
Iodine:
Functions: Thyroid gland function (controls how quickly the body uses
energy) and body metabolism
Deficiency: Particularly in children, fall in the production of thyroid
hormones
Sources: Animal and plat life from the sea, milk, eggs, yogurt
Conclusion
71
71. 1. Minerals are inorganic and are found in rocks and soil.
2. Major Minerals required in larger quantities are sodium, potassium,
calcium and phosphorus.
3. Trace Minerals required in tiny amounts are iron, zinc and iodine.
4. Each type of elements have it's own importance and needed for healthy
body.
MCQ
Q.1- Which of the following is a simple sugar or monosaccharide?
a) Galactose
c)Maltose
b) Lactose
d)Sucrose
(a)
Q.2- What is the molecular formula for Glucose?
a) CH3OH
c)C12H22O11
b) C6H1206
d)C6H12O5
(b)
Q.3- Maltose is composed of which two sugars?
a) Glucose and Glucose
c) Glucose and Fructose
b) Glucose and Galactose
d) Fructose and Galactose (a)
Q.4- In which form Glucose is stored in animals?
a) Starch
c)Dextrins
b) Glycogen
d)Cellulose
71
(b)
72. Q.5-All are glucosans excepta) Glycogen
b) Inulin
c)Starch
d)Cellulose
(b)
Q.6- Choose the Aldose sugara) Sucrose
b) Ribulose
c)Fructose
d)Ribose
(d)
Q.7- Choose the keto triosea) Glyceraldehyde
b)
Erythrose
c) Dihydroxyacetone
d)Arabinose
Q.8- A pentose sugar present in the heart muscle isa) Xylose
c)Xylulose
b)Lyxose
d)Aldose
(c)
(b)
Q.9- α-D Glucose and β- D glucose area) Epimers
c)Anomers
b) Keto- Aldose Isomers
d) Optical isomers
Q.10- All tests arenegative for sucrose excepta) Benedict
c)Barfoed
b)
Seliwanoff
d)Osazone
(c)
(b)
Q.11- Glucose canhave ————- isomers due to the presence of 4
asymmetric carbon atomsa) 4
c)8
b)
12
d)16
(d)
Q.12- Galactose andGlucose area) Epimers
c)Anomers
b) Isomers
d)Ketose- Aldose isomers
(a)
Q.13- The compounds having same structural formula but differing in
configuration around one carbon atom are calleda) Optical isomers
c) Anomers
72
73. b) Stereo isomers
Epimers
d)
(d)
Q.14- What does the following equation represent?
α-D Glucose +112ο→+52.5 ο → +19 ο β- D glucose
a) Stereoisomerism
c) Opticalisomerism
b) Mutarotation
d)Epimerization
Q.15- Thecarbohydrate of blood group substance isa) Fucose
c)Lyxose
b) Xylose
d)Fructose
Q.16- Dulcitol isa a) Sugar acid
b) Amino sugar
c) Deoxysugar
d) Sugaralcohol
Q.17- Which of thefollowing is a non reducing sugara) Arabinose
c)Trehalose
b) Erythrose
d)Ribulose
(b)
(a)
(d)
(c)
Q.18- APolysaccharide formed by β1→4 Glycosidic linkages isa) Starch
c)Glycogen
b) Dextrin
d)Cellulose
(d)
Q.19-Invert sugarisa) Starch
b) Glucose
c)Fructose
d)Hydrolytic product of Sucrose
(d)
Q.20- Thepolysaccharide found in the exoskeleton of insects isa) Hyaluronic acid
c) Chitin
b) Cellulose
d)Chondrosamine
(c)
Q,21- Which of thefollowing is a polymer of fructose?
a) Inulin
c)Cellulose
b)Dextrin
d)Glycogen
(a)
Q.22- Adisaccharide produced on hydrolysis of starch is calleda) Sucrose
c)Maltose
b) Lactose
d)Trehalose
(c)
73
74. Q.23- The typicalcyclical structure of Glucose is α and β Da) Glucopyranose
c)Glucofuranose
b) Glucoside
d)Glucosamine
(a)
Q.24- Which testcan be undertaken to differentiate between Glucose and
Fructose?
a) Benedict
c)Seliwanoff
b) Molisch
d)Osazone
(c)
Q.25- Which of thefollowing molecules is a carbohydrate?
a) C3 H7O2N
c)C6H12O6
b) C13H26O2
d)C20H40O2
(c)
Q.26- Which of the followingmonosaccharides is not an aldose?
a) Ribose
c) Glucose
b) Fructose
d)Glyceraldehyde
(b)
Q.27-Which of following is ananomeric pair?
a) D-glucose and L-glucose
c) D-glucose andD-fructose
b) α-D-glucose and β-D-glucose
d) α-D-glucose and β-L-glucose
(b)
Q.28- Which of the followingmonosaccharides is not a carboxylic acid?
a) Glucuronate
c) Glucose
b) Gluconate
d)Muramic acid
(c)
Q.29- From the abbreviated nameof the compound Gal (β 1 →4) Glc, we
know that:
a) The glucose residue is the β anomer.
b) The galactose residue is at thenonreducing end.
c) C-4 of glucose is joined toC-1 of galactose by a glycosidic bond.
d) The compound is in its
furanoseform
(c)
74
75. 1. The general formula of monosaccharides is
(A) CnH2nOn (B) C2nH2On
(C) CnH2O2n (D) CnH2nO2n
2. The general formula of polysaccharides is
(A) (C6H10O5)n (B) (C6H12O5)n
(C) (C6H10O6)n (D) (C6H10O6)n
3. The aldose sugar is
(A) Glycerose (B) Ribulose
(C) Erythrulose (D) Dihydoxyacetone
4. A triose sugar is
(A) Glycerose (B) Ribose
(C) Erythrose (D) Fructose
5. A pentose sugar is
(A) Dihydroxyacetone (B) Ribulose
(C) Erythrose (D) Glucose
6. The pentose sugar present mainly in the heart muscle is
(A) Lyxose (B) Ribose
(C) Arabinose (D) Xylose
7. Polysaccharides are
(A) Polymers (B) Acids
(C) Proteins
(D) Oils
8. The number of isomers of glucose is
(A) 2 (B) 4
(C) 8
(D) 16
9. Two sugars which differ from one another only in configuration
around a single carbon atom are termed
(A) Epimers (B) Anomers
(C) Optical isomers (D) Stereoisomers
10. Isomers differing as a result of variations in configuration of the —
OH and —H on carbon atoms 2, 3 and 4 of glucose are known as
(A) Epimers (B) Anomers
75
76. (C) Optical isomers (D) Steroisomers
11. The most important epimer of glucose is
(A) Galactose (B) Fructose
(C) Arabinose (D) Xylose
12. α-D-glucose and β -D-glucose are
(A) Stereoisomers (B) Epimers
(C) Anomers (D) Keto-aldo pairs
13. α-D-glucose + 1120 → + 52.50 ← + 190 βD-glucose for glucose above represents
(A) Optical isomerism (B) Mutarotation
(C) Epimerisation (D) D and L isomerism
14. Compounds having the same structural formula but differing in
spatial configuration are known as
(A) Stereoisomers (B) Anomers
(C) Optical isomers (D) Epimers
15. In glucose the orientation of the —H and —OH groups around the
carbon atom 5 adjacent to the terminal primary alcohol carbon
determines
(A) D or L series
(B) Dextro or levorotatory
(C) α and β anomers
(D) Epimers
Answer
1. A 2. A 3. A 4. A 5. B 6. A
7. A 8. D 9. A 10. A 11. A 12. C
13. B 14. A 15.
76
77. Amino Acids Quiz
1. Which of the following is most found in protein molecule?
a. Carbon
b. Hydrogen
c. Oxygen
d. Nitrogen
2. No of naturally occuring aminoacids is :
a. 10
b. 20
c. 30
d. 40
3. All of the following are aliphatic amino acids except :
a. Glycine b. Alanine c. Proline d. Lysine
4. One of the following is neutral amino acid :
a. Arginine
b. Lysine
c. Glutamine d. Valine
5. All of the following are hydroxy containing amino acids except :
a. Serine
b. Threonine c. Valine
d. Tyrosine
6. One of the following is optically non active amino acid
a. Valine
b. Tyrosine
c. Glycine
d. Threonine
7. All of the following are polar amino acids except:
a. Serine
b. Glutamate c. Arginine
d. Alanine
8. All of the following are essential amino acids except :
a. Lysine b. Aspartate
c. Tryptophan d. Hisitidine
9. Lysine:
a. Basic Only ketogenic b. Ketogenic glucogenic c. Acidic glucogenic
d. Non essential
10. All of the following are primary aminoacids except:
a. Cysteine
b. Cystine c. Alanine d. Arginine
11. Which of the following is precursor of T3 and T4 :
a. GABA
b. Dopa c. B- Alanine
d. Di-iodotyrosine
12. Zwitter ion are:
a. Basic b. Acidic
c. Neutral d. Carry both -ve & +ve charges e.
Both c and d
13. The unit of peptides is:
a. Moiety
b. Residue c. Polypeptide d. Both a and b
14. Lactic acid is buffered by:
a. L.Carnosine b. Glutathione c. Casenogin
d. Dopa
15. N terminal of glutathione is:
a. Glycine b. Cysteine
c. Glutamate
d. Aspartate
16. Which of the following is BLOOD iron carrier?
a. Haemoglobin b. Albumin c. Transferrin
d. Globulin
17. Storage form of iron:
a. Transferrin b. Ferritin c. Myosin d. Actin
18. Which of the following protein is found in bone :
a. Keratin b. Ossein c. Mucin d. Actin
77
78. 19. Type of bonds between C terminal and N terminal is:
a. Covalent
b. Disulphide bond c. Peptide
d. Ionic e. Both a
and c
20. Type of bond between nitrogen and carbonyl group:
a. Hydrogen bonds b. Covalent bond c. Peptide bond d. Disulphide
bond
21. All of the following are non covalent except:
a. Hydrophobic interactions b. Disulphide bond
c. Hydrogen bond
d. Electrostatic bond
22. Primary structure of proteins refers to:
a. Coiling and folding in form of specific structure
b. Number of amino acids in a chain
c. 3D structure
d. Alpha and Beta sheets
23. Denaturation involves:
a. Peptide bonds
b. Primary structure of protein c. Secondary
structure
d. Function
e. Both c and d
24. Tertiary structure of proteins involves EXCEPT:
a. Domains b. Globular
c. Fibrous
d. Beta sheets
25. All of the following are simple proteins except :
a. Histones b. Albumin c. Keratins d. Glycoprotein
26. Which of the following is sulphur highly containing protein :
a. Collagen
b. Keratin c. Ossein
d. Reticulin
27. Casenogen is
a. Chromoprotein
b. Phosphoprotein c. Glycoprotein d.
Lipoprotein
28. X-ray is a chemical agent for protein denaturation
a. True b. False
29. Increase viscosity of proteins is due to
a. Denaturation b. Isoelectric point c. Both d. None
30. Separation of low molecular weight protein from high one is:
a. Dialysis
b. Cromotography
c. Electrophoresis d.
Ultracentrifugation
31. Example of basic essential amino acids
a. Arginine
b. Histidine
c. Lysine
e. None of the above
32. Example of non-protein amino acid
78
d. All of the above
79. a. Glycine
b. Alanine
c. Tryptophan d. All of the above e.
None of the above
33. Example of non-protein amino acid
a. Alanine
b. Citrulline
c. Phenylalanine
d. Leucine
34. Glutathione is an example for
a. Amino acid
b. Dipeptide c. Polypeptide d. Protein e.
Tripeptide
35. The active group of glutathione is
a. Amino group b. Sulfhydryl group c. Carboxylic group d. Imino
group e. Peptide linkage
36. The peptide bond is
a. Covalent bond b. Non-covalent bond c. Weak bond
37. First order of protein structure refers to
a. Bending of protein chain
b. Number and sequence of amino acids
c. Three dimensional structure of protein
d. Site of disulfide
bonds
e. Non-covalent bonds in protein molecule
38. Second order of protein structure refers to
a. Number and sequence of amino acids
b. Three dimensional structure of protein
c. Proteins formed of more than one monomer
d. Bending of protein molecule
e. Dependence on covalent bonds
39. Third structure of protein structure refers to
a. Number and sequence of amino acids
b. Three dimensional structure of protein
c. Proteins formed of more than one monomer
d. Bending of protein molecule
e. Dependence on covalent bonds
40. Fourth structure of protein structure refers to
a. Proteins formed of more than one monomer
b. Myoglobin is an example.
c. Depends on covalent bonds d. None of the above
e. All of the above
41. Covalent bond is a. A weak bond
b. A true chemical bond c. A hydrogen bond
d. Responsible for secondary structure of protein
79
80. e. Liable to be destroyed
42. Example of essential aromatic amino acids
a. Threonine b. Alanine c. Phenyl alanine
d. Glycine
e. Cysteine
43. Protein of high biological value
a. Contains essential amino acids
b. Is poor in essential amino acids
c. Is of plant source
d. Contains amino acid glycine
e. Is a basic
protein
44. Albumin is
a. Insoluble in water
b. Heat coagulable protein c. A plant protein
d. A protein of low biological value
e. Poor in essential amino acids
45. Globulin is
a. A basic protein
b. A protein of low molecular weight
c. Heat coagulable protein
d. Easily soluble in water e. A fibrous protein
46. Keratin is
a. Protein of tendons b. Rich in sulfur
c. Poor in cysteine
d. Conjugated protein e. Soluble in water
47. Collagen contains high percentage of
a. Glycine b. Tryptophan
c. Phenyl alanine d. Serine
e. Valine
48. Caseinogen is
a. Simple protein b. Derived protein
c. Phosphoprotein
d. Rich in sulfur containing amino acids
e. Present in plasma
49. On electrophoresis for plasma proteins using buffer of pH 8.6
a. The proteins are neutral
b. The proteins carry negative charge
c. The proteins carry positive charge
d. The proteins are easily precipitated
e. The proteins are denaturated
50. Albumins are separated by
a. 1/2 saturated ammonium sulfate
81
81. b. Full saturated ammonium sulfate
c. 20% saturated ammonium sulfate
d. 60% saturated ammonium sulfate
e. 10% saturated ammonium sulfate
51. Albumins and globulins are defined as:
a. Derived protein
b. Conjugated protein
c. Fibrous protein
d. Globular protein
e. Lipoprotein
52. Plasma proteins are separated by
a. Dialysis
b. Electrophoresis
precipitation
c. Filtration
d. Alcohol
53. Example of essential sulphur containing amino acids
a. Lysine
b. Cysteine c. Cystine d. Alanine
e. Methionine
54. The bonds present in the primary structure of protein are
a. Peptide bonds
b. Hydrogen bonds
c. Disulfide bonds
d. All of these
55. A protein rich in proline and hydroxy proline is
a. Globin b. Collagen
c. Casein
d. Histone
56. The buffering property of proteins is due to the presence of
a. Acidic and basic groups
b. Hydrogen bonds c. Indole groups
d. Hyrophobic bonds
57. Arginine, lysine and ornithine are
a. Obtained by hydrolysis of proteins
b. Essential amino acids c. Basic amino acids
d. Derived from butyric acid
58. Glycine Is characterized by
a. Absence of an asymmeteric carbon
b. Absence of optical activity c. The shortest amino acid d. All of these
59. Ornithine is
a. A basic amino acid
b. An essential amino acid
c. Present in protein structure d. All of these
81
82. 60. Albumin, globulin and casein are
a. Milk proteins
b. Plasma proteins c. Egg proteins
d. Meat proteins
61. Cysteine, cystine and methionine are
a. Essential amino acids
b. Present in protein structure c. Acidic amino acids
d. All of these
62. A protein that gives positive biuret test is
a. Albumin
b. Globulin
c. Casein
d. All of these
63. A basic amino acid present in protein structure is
a. Histidine b. Citruline c. Ornithine
d. All of these
64. Example of amino acid containing guanido group
a. Arginine
b. Lysine
c. Histidine
d. Valine
e. Leucine
65. Keratin is
a. A scleroprotein
c. A simple protein
b. Rich in cystine
d. All of these
66. A fibrous protein is
a. Albumin
b. Myosin
c. Casein
d. Globulin 67. Glycine is
a. A non-optically active amino acid
b. Present in structure of glutathione
c. A neutral amino acid d. All of these
68. Proteins associated with nucleic acid in nucleo-protein are
a. Albumin b. Globulin c. Keratin d. Histones
69. ln proteins, the alpha-helix and Beta-pleated sheet are examples of
a. Primary structure
b. Secondary structure c. Tertiary structure
d. Quaternary structure
70. A tetra peptide contains the following number of preptide bonds
82
83. a. Two
b. Three
c. Four
d. Five
71. A globular protein is
a. Actin
b. Myosin
c. Collagen
d. Albumin
72. Example of branched amino acid
a. Valine
b. Leucine
c. Isoleucine
d. All of the above e.
None of the above
73. Example of hydroxy containing amino acids
a. Serine b. Phenyl alanine
c. Tryptophan
Glutamic acid
d. Proline
74. Example of amino acids containing imino group
a. Glycine b. Valine
c. Proline
d. Lysine
e.
e. Phenyl alanine
75. Example of an amino acid containing sulfhydryl group
a. Alanine
b. Cysteine
c. Proline d. Tryptophan
e. Lysine
76. Example of non-optically active amino acid
a. Proline
b. Alanine
c. Glycine
d. Phenylalanine
77. Which of the following statements about amino acids is not true?
a. Amino acids are ampholytes
b. Amino acids are linked through peptide bonds to form proteins
c. Amino acids are not Crystalline compounds
d. Leucine is a purely ketogenic amino acid
78. The amino acids found in biological proteins are of:
a. D-Configuration and dextrorotatory
b. L-Configuration and levorotatory
c. D-Configuration and levo/dextrorotatory
d. L-Configuration and dextro/laevoratatory
79. Which amino acid doesn’t occur in proteins of biological system?
a. Ornithine
b. Arginine
c. Cystine
d. Histidine
80. All amino adds are optically active except:
a. Serine b. Glycine c. Tryptophan d. Threonine '
81. Which of the following amino acids possesses an imino group?
a. Tryptophan
b. Hydroxylysine c. Tyrosine d. Proline
82. An amino acid which contains a disulphide bond is:
a. Lysine
b. Methionine
c. Homocysteine
83
d. Cystine
84. 83. Chemically keratin is a:
a. Globulin b. Fibrous protein
c. Tripeptide
d. Conjugated protein
84. The most abundant protein in the human body is:
a. Collagen
b. Keratin
c. Myosin
d. Albumin
85. Denaturation of proteins is often characterised by:
a. Loss of biological activity
b. Always being irreversible
c. Being greater the lower the temperature
d. Changes in primary structure
86. Decarboxylation of amino acids will result in the formation of:
a. Amines
b. Imino acids
c. Basic amino acids
d. Amides
87. The number of amino acid residues in one spiral of alpha- helix of
proteins is usually:
a. 2.6
b. 3.6
c. 4.6
d. 5.6
88. Which of the following is not found in proteins?
a. Citrulline
b. Arginine
c. Methionine
d. Cysteine
89. The only amino acid containing indole ring is:
a. Tryptophan
b. Tyrosine c. Histidine
d.
Phenylalanine
90. With the exception of glycine, all amino acids found in proteins are:
a. Optically active
b. Dextrorotatory
c. Of L-configuration d. Levorotatory
91. Essential amino acids are so named because:
a. They are essential for life process
b. Cannot be synthesized in the body
c. Deficiency leads to genetic diseases
d. Important in cell growth
92. Casein is a:
84
85. a. Lipoprotein b. Mucoprotein
d.Chromoprotein
c. Phosphoprotein
93. Which is a basic amino acid?
a. Lysine
b. Tyrosine
c. Glycine
94. An amino acid containing imidazole group is:
a. lsoleucine
b. Arginine
c. Proline
d. Leucine
d. Histidine
95. The major linkage between amino acids in protein is the:
a. Hydrogen bond b. Ionic bond
c. Sulphide bond d. Peptide bond
96. An example of a chromoprotein is:
a. Casein
b. Hemoglobin c. Peptone d. Collagen
97. When a peptide bond is formed there is removal of :
a. CO2
b. H2O
c. NH3
d. H+
98. Aspartic acid is a (an):
a. Monoamino dicarboxylic acid
b. Diamino monocarboxylic acid
c. Aromatic amino acid
d. Imino acid
99. All amino acids are optically active except:
a. Glycine
b. Serine
c. Threonine
d. Tryptophan
100. Amino acid which synthesizes many hormones is:
a. Valine b. Phenylalanine c. Alanine
d. Histidine
1. A
2. B
3. C
26. B
27. B
28. B
51. D
76. D
52. B
53. E
77. C
78. D
85
86. 4. C
5. C
6. C
7. D
8. B
9. B
10. B
11. D
12. D
13. D
14. A
15. C
16. C
17. B
18. B
19. E
20. A
21. B
22. B
23. E
24. D
25. D
29. A
30. A
31. D
32. E
33. B
34. E
35. B
36. A
37. B
38. D
39. B
40. A
41. B
42. C
43. A
44. B
45. C
46. B
47. A
48. C
49. B
50. B
54. A
55. B
56. A
57. C
58. D
59. A
60. A
61. B
62. D
63. A
64. A
65. D
66. B
67. D
68. D
69. B
70. B
71. D
72. D
73. A
74. C
75. B
79. A
80. B
81. D
82. D
83. B
84. A
85. A
86. A
87. B
88. A
89. A
90. A
91. B
92. C
93. A
94. D
95. D
96. B
97. B
98. A
99. A
100.b
86
