07 Proteins Diversity

Question 1

What type of protein are collagen and keratin?

Answer 1

Fibrous proteins

Question 2

How many helices in collagen?

Answer 2

3 (triple helix)

Question 3

Handedness of each alpha helix strand in collagen?

Answer 3

Left handed

Question 4

Handedness of the collagen superhelix?

Answer 4

Right

Question 5

3 major amino acids in collagen

Answer 5

Glycine
Proline
Hydroxyproline

Question 6

Cause of osteogenesis imperfecta

Answer 6

mutations in type I collagen

Question 7

Symptoms of osteogenesis imperfecta

Answer 7

increased bone fractures and collagen defects

Question 8

Which vitamin is required for proline hydroxylation

Answer 8

Vitamin C

Question 9

Is vitamin C an oxidizing or reducing agent?

Answer 9

Reducing agent

Question 10

Role of vitamin C in proline hydroxylation

Answer 10

Sodium ascorbate is a reducing agent and keeps the Fe2+ reduced as a cofactor for sustained prolyl 4-hydroxylase activity

Question 11

Lack of vitamin C leads to

Answer 11

scurvy - gum disease, loosening of teeth, malaise/lethargy

Question 12

How many keratin alpha helices are coiled together to form a coil?

Answer 12

2

Question 13

Keratin is stabilized by

Answer 13

disulphide bridges

Question 14

Which parts of the body is keratin present in?

Answer 14

Hair, skin, nails

Question 15

Function of myoglobin

Answer 15

carry oxygen in muscle

Question 16

How many haem in myoglobin?

Answer 16

1

Question 17

What kind of group is haem?

Answer 17

Prosthetic group

Question 18

What is the oxygen carrier in neurons?

Answer 18

neuroglobin

Question 19

What kind of cooperativity is present in haemoglobin?

Answer 19

Positive cooperativity

Question 20

What change is responsible for positive cooperativity?

Answer 20

Structural change

Question 21

Which state has higher affinity for oxygen in haemoglobin?

Answer 21

R state

Question 22

What is the advantage of positive cooperativity in haemoglobin?

Answer 22

Enables saturating of haemoglobin oxygen in lungs, but also release oxygen to myoglobin in tissues

Question 23

Why is carbon monoxide toxic?

Answer 23

Carbon monoxide binds to haem and lock haemoglobin in R state (high affinity) -> disrupt haemoglobin cooperativity

Question 24

Cause of prion diseases?

Answer 24

misfolded proteins

Question 25

What is the association of misfolded protein to Alzheimer disease?

Answer 25

amyloid-beta peptide self-associating into fibrils then into amyloid plaques

Question 26

Function of a molecular chaperone

Answer 26

helps protein fold into the correct conformation