carbohydrates 1

Question 1

disaccharide definition

Answer 1

formed from monomers that are linked by glycosidic bonds
Covalent bond formed when hydroxyl group of onemonosaccharide reacts with anomeric carbon of anothermonosaccharide

Question 2

examples of disaccharides

Answer 2

maltose, lactose, sucrose

Question 3

What’s an anomeric carbon?

Answer 3

carbon in a sugar that is an aldehyde or ketone in the open-chain form and becomes a stereocenter in the cyclic form
Different anomers are mirror images (stereoisomers) of each other(left- and right-handed forms)* It is carbon #1 on the glucose residue* It stabilises the structure of glucose* Is the only residue that can be oxidised

Question 4

polysaccharide definition

Question 5

Homopolysaccharides definition

Question 6

Heteropolysaccharides definition

Question 7

examples of polysaccharides

Answer 7

starch, glycogen

Question 8

Why store glucose in polymers?

Answer 8

Compactness

Amylopectin and glycogen have non-reducing ends which allow them to be readily synthesised and degraded to and from monomers respectively so speeds up the formation or degradation

The polymers form hydrated gels and are osmotically inactive– If free glucose were in the cells then [Glc]inside > > [Glc]outside– Either Glc would move out of the cell down the concentration gradient– Or, the cell would use huge amounts of energy keeping it in the cell

Question 9

what are the two types of glucose polymer that make up starch?

Answer 9

amylose and amylopectin

Question 10

amylose structure

Answer 10

20% of starch
alpha d
unbranched chain
joined by 1,4 glycosidic bonds
coiled, compact and store lots of energy

Question 11

amylopectin structure

Answer 11

branched chain
glucose joined by 1,4 and 1,6 bonds
many side branches can be acted upon simultaneously by enzymes and broke down to release energy

Question 12

cellulose formed by which type of glucose molecule?

Answer 12

beta

Question 13

glycogen and starch formed by which type of glucose molecule?

Answer 13

alpha

Question 14

properties of starch:

Answer 14

undergoes hydrolysis to yield constituent sugars
insoluble in water and forms gel
undergoes decomposition upon heating and forms dextrin
blue colour in iodine solution

Question 15

glycogen structure

Question 16

glycoproteins

Answer 16

Proteins that have carbohydrates covalently attached

Question 17

carbohydrates attached to proteins in glycoproteins may:

Answer 17

– Increases the protein’s solubility
– Influence protein folding and conformation
– Protect it from degradation
– Act as communication between cells