Amino Acids

Question 1

Taurine

Answer 1

Bile acids

Question 2

Beta alanine

Answer 2

Coenzyme A

Question 3

Homocysteine

Answer 3

Assess risk of coronary artery disease

Question 4

Ornithine and citrulline

Answer 4

Urea cycle

Question 5

Hydroxy proline and hydroxy lysine

Answer 5

Collagen

Question 6

Desmosine

Answer 6

Elastin

Question 7

Methyl lysine

Answer 7

Contractile protein

Question 8

Gamma carboxy glutamate

Answer 8

Prothrombin

Question 9

DOPA

Answer 9

DihydrOxy PhenylAlanine

Precursor for melanin

Question 10

GABA

Answer 10

Gamma Amino Butyric Acid

Neurotransmitter

Question 11

ALA

Answer 11

Delta AminoLevulinic Acid

Synthesis of heme

Question 12

SAM

Answer 12

S-Adenosyl Methionine

Methyl donor

Question 13

Ketogenic Amino acids

Answer 13

Leucine

Question 14

Ketogenic and glucogenic Amino acids

Answer 14

Isoleucine
Lysine
Phenylalanine
Tyrosine
Tryptophan

Question 15

21 & 22 AA

Answer 15

Selenocysteine

Pyrrolysine

Question 16

Toxin in lathyrism

Answer 16

Beta oxalyl aminoalanine that inhibits enzyme lysyl oxidase. Affects lysine linkage in collagen.

Question 17

Osteogenesis imperfecta

Answer 17

Mutations in type 1 collagen fibres
Prevents triple Helix formation
Genetic
Brittle bone disease
-bone fragility
-hearing loss
-blue sclerae

Question 18

Alport syndrome

Answer 18

Defect in type 4 collagen fibres found in basement membrane of renal glomeruli
Hematuria, end stage renal disease

Question 19

Epidermolysis bullosa

Answer 19

Blisters and cracks in skin

Type 7 collagen

Question 20

Ehlers danlos syndrome

Answer 20

Hyperextensability of joints and skin

Question 21

O linked glycoproteins

Answer 21

N acetyl galactosamine + serine/threonine

Ex: mucins on surfaces of cells of GIT

Question 22

N linked glycoproteins

Answer 22

N acetyl glucosamine + asparagine occurs in ER or GA

Ex: plasma proteins

Question 23

GPI linked glycoproteins

Answer 23

Anchored to plasma membrane by glucose phasphatidyl inositol.

Ex: enzyme acetyl cholinesterase on rbc membrane

Question 24

Properties of peptide bond

Answer 24

1. Planar
2. Partial double bond character
3. Rigid. Prevents rotations around bond
4. Polar covalent bond with no net electric charge to allow packing into globular structures and polar groups involved in hydrogen bonding
5. All peptide bonds exist in trans form due to less stearic clashes

Question 25

Phi and psi angles

Answer 25

Rotation between N and C — phi
Rotation between C and C — psi

The angles determine path of polypeptide chain

Question 26

Features of alpha Helix

Answer 26

• most common
• most stable
• always right handed
• backbone forms inner part while side chains extend outwards
• each turn is 5.4A and has 3.6 AA residues
• each AA forms bond with fourth AA in linear sequence
• proline fits only in first turn

Question 27

Features of beta pleated sheet

Answer 27

• distance between adjacent AA is 3.5Å
• side chains are in opposite directions
• stabilised by h bonds
• adjacent chains can run parallel, antiparallel or mixed

Question 28

Features of denaturation

Answer 28

1. Loses 3D form. Loses biological activity
2. Primary structure is intact as peptide bonds are not hydrolysed
3. Usually irreversible

Question 29

Enzymes aiding protein folding

Answer 29

1. Disulphide isomerase - prevents incorrect disulphide cross links
2. Cis trans isomerase - catalyses interconversion of cis trans isomers of proline