BGM1002/L11 Carbohydrates II

Question 1

What is maltose?

Answer 1

Disaccharide of glucose + glucose
Major product generated from starch digestion

Question 2

What is lactose?

Answer 2

Disaccharide of glucose + galactose
Milk sugar

Question 3

What is sucrose?

Answer 3

Disaccharide of glucose + fructose
Transport form of carbohydrate from plants (table sugar)

Question 4

Name 2 important energy storage molecules in the human body.

Answer 4

Starch
Glycogen

Question 5

What types of glycosidic bond exist in starch and glycogen?

Answer 5

Alpha-1,4
Alpha-1,6

Question 6

Where can starch be found? (2)

Answer 6

Plants
Human food sources

Question 7

Where is glycogen found?

Answer 7

Animals

Question 8

Which end of a polysaccharide is the reducing end?

Answer 8

Terminal in which C1 is unattached

Question 9

Which end of a polysaccharide is the non-reducing end?

Answer 9

The terminal in which C1 is involved in a glycosidic bond
Cannot reduce other molecules

Question 10

What causes some polysaccharides to twist into a helical structure?

Answer 10

Alpha-1,4-glycosidic bonds

Question 11

Why is a helical structure favourable for sugars? (2)

Answer 11

More compact
Easily accessible

Question 12

Where is cellulose found?

Answer 12

Plant cell walls

Question 13

What causes cellulose chains to be planar?

Answer 13

Beta-1,4-glycosidic bonds

Question 14

How do cellulose chains pack together?

Answer 14

Hydrogen bonds between chains

Question 15

Where is peptidoglycan found?

Answer 15

Bacterial cell walls

Question 16

What is a glycoconjugate?

Answer 16

A carbohydrate covalently bonded to other molecules e.g., proteins and lipids

Question 17

Give a function of glycolipids.

Answer 17

Receptors for cell recognition

Question 18

What are N- and O-linked glycoproteins

Answer 18

N- nitrogen-linked
O- oxygen-linked

Question 19

What 3 functions does N-glycosylation have?

Answer 19

Protein folding
Stability
Cell recognition

Question 20

What are N-linked glycoproteins attached to?

Answer 20

Amide group of asparagines

Question 21

What are O-linked glycoproteins attached to?

Answer 21

Hydroxyl group of serine or threonine

Question 22

What kind of glycosylation plays a role in mucins?

Answer 22

O-glycosylation

Question 23

What is a glycosaminoglycan?

Answer 23

Protein attached via O-linkage to polysaccharides

Question 24

Give 2 functions of proteoglycans.

Answer 24

Joint lubricants
Structural components of ECM
Mediate adhesion of cells to ECM
Bind factors that stimulate cell proliferation

Question 25

Which component of proteoglycans determines function?

Answer 25

GAG

Question 26

What are proteoglycans composed of?

Answer 26

Disaccharide repeats of amino sugar and uronic acid sugar

Question 27

What is the function of glycotransferases?

Answer 27

Transfer of sugars from nucleotides onto other molecules

Question 28

What is the initial step of a viral infection?

Answer 28

Binding of spike protein surface to human angiotensin-converting enzyme 2 (ACE2) receptor

Question 29

What is passive ‘antibody shielding’?

Answer 29

Antibodies bind to spike protein and ‘block’ interaction between virus and ACE2

Question 30

What role do N-glycans play in RBD?

Answer 30

They stabilise the ‘up’ state of spike protein