4. Carbohydrates

Question 1

Brief importance of carbohydrates (4)

Answer 1

• Major means of storing energy in plants and animals.
• Structural components of nucleus acids.
• cell walls in bacteria
• main component of cellular recognition, such as antigens.

Question 2

Definition of carbohydrate

Answer 2

A carbohydrate is a compound with 3 or more carbon atoms which has an aldehyde or keto functional group and two or more hydroxyl groups.

Question 3

Monosacharides

Answer 3

Simplest sugar, >3 C but typically up to 7C. Some also have P,S atoms. Poly hodroxy aldhydes or ketones.

Question 4

Tetroses have how many carbons?

Answer 4

4

Question 5

Oligosacharides

Answer 5

Have 2 or more sugar units. Most common are disaccharides and trisacharides.

Question 6

Polysacharides

Answer 6

Have many units of sugars in them, they are polymers and can be infinite units.

Question 7

Monosacharides can be divided into 2 groups….

Answer 7

Aldehydes or ketones.

Trioses are aldotriose of ketotriose etc.

Question 8

Simplest carbohydrate monosacharides

Answer 8

Glyceraldehyde and dihydroxyacetone

Question 9

Term for Mirror image isomers?

Answer 9

Enantiomers

Stereoisomers (optical isomer)

Question 10

D structural form (right) of carbohydrates is the

Answer 10

Naturally occurring form. Not the L form.

Question 11

Epimers

Answer 11

Optical isomers or stereoisomers. The same except for the configuration around one carbon atom.

Question 12

Diastereoisomer

Answer 12

Related to epimers although with Differences around multiple carbons rather than just one.

Question 13

Most important carbohydrate molecule

Answer 13

D-glucose

Question 14

Conjugated carbohydrate examples

Answer 14

DNA, Blood groups are dependent on the conjugation differences.
Peptidoglycan, keratin sulphates.

Question 15

Chiral centre means that the compound can have…..

Answer 15

It is possible to have optical isomers of the carbohydrate.

Question 16

Anomers

Answer 16

Two compounds are anomers if they differ in configuration only around the carbon atom that may yield a carbonyl group on hydrolysis (the potential carbonyl carbon).

Question 17

Mutarotation

Answer 17

The process by which an anomer is inter-converted into the allowing anomer.

Question 18

Haworth formulae used to tell which isomer you are looking at.

Answer 18

• If carbon 6 is above the ring, it is a d sugar, and if it is below the ring it is an L-sugar.
• if the hydroxyl group on the anomer if carbon (c1 for aldoses) is above the ring it is a beta. Below it is an alpha

Question 19

If the hydroxyl group is lower than the plain of the cyclic compound, the compound is considered…

Answer 19

An Alpha form

Question 20

Does glucose have reducing ability and why?

Answer 20

Yes, due to the functional group not inside the ring.

Question 21

Does sucrose have reducing ability? And why?

Answer 21

Nope, sucrose functional group is encircled in the cyclic nature of sucrose.

Question 22

Glycosidic bond

Answer 22

Two -OH groups react together to form a bond. For example methanol and glucose can form a glycosidic bond.

Question 23

What is a disaccharide ?

Answer 23

Is a compound made from two sugar units joined by a glycosidic bond. Lactose, maltose, sucrose

Question 24

Maltose has what sugar units?

Answer 24

Glucose with a glycosidic bond to glucose

Question 25

Lactose is made of what sugar units?

Answer 25

Glucose with a glycosidic bond to galactose.

Question 26

Sucrose

Answer 26

Glucose + fructose.

Very sweet. A glucose and b fructose unit.

Question 27

Homopolysaccharides

Answer 27

Starch, glycogen and cellulose: all of which are composed of glucose units arranged differently/joined together.

Question 28

Starch contains two types of glucose polymers…

Answer 28

Amylose and amylopectin.

Question 29

Amylose consists of

Answer 29

Glucose units joined by a links

Question 30

Amylopectin consists of

Answer 30

Glucose joined by alpha links with some branches alpha 1-6 links.

Question 31

Where is glycogen stored in the body?

Answer 31

Liver and muscles.

Question 32

Substances that contain repeating segments which consist of two or more different carbohydrate units.

Answer 32

Heteropolysaccharides

Question 33

Polysaccharides that contain only one type of sub unit.

Answer 33

Homopolysaccharides

Question 34

Botrytis produces large amounts of polyphenol oxidase and charecteristic….. ………

Answer 34

Carbohydrate polymer. The polymer rapidly blocks the small pore sized filters used in bulking bottle fermentation. Trichoderma viride van cleave this polymer allowing more efficient filtration.

Question 35

a - amylase

Answer 35

Severs glycosidic bonds at any 1-4 bond position in the molecule chain.
(Endoamylase)

Question 36

b - amylase

Answer 36

Breaks down starch during malting of barley for beer. It cleaves starch molecules at every second 1-4 glycosidic bond.

Question 37

Role of glycogen in animals

Answer 37

Energy storage in animals, mainly in the liver.

Question 38

How glycogen differs structurally to cellulose?

Answer 38

Both made up of repeating units of glucose. In cellulose the gluc units are joined by a beta 1-4 glycosidic bond, while in glycogen the bonds are alpha 1-4 with alpha 1-6 branch points.

Question 39

Difference between beta and alpha glycosidic bonds?

Answer 39

Celluloses stereochemistry allows it to pack more uniformly giving it a stronger structure with beta glycosidic bonds/linkages. Connects at the 1-4 carbon. Alpha connects at the 1-6 carbon allowing it to branch.