Carbohydrates

Question 1

Name the 4 types of carbohydrates

Answer 1

1. Monosaccharides
2. disaccharides
3. oligosaccharides
4. polysaccharides

Question 2

What is a monosaccharide and describe it associated structure

Answer 2

• simple sugar
• smallest unit
• alphac(OH in opposite directions) & beta glucose

Question 3

What is a disaccharide and describe it associated structure

Answer 3

• 2 monosaccharides
• from 1-4 glycosidic bonds depending on configuration
• fromed by condensation reaction

Question 4

What is a oligosaccharides and describe it associated structure

Answer 4

• 2 up to 20 monosaccharides in a chain

Question 5

What is a polysaccharide and describe it associated structure

Answer 5

• 20+ amino acids
• Homopolysaccharides e..g, starch , glycogen, cellulose

Question 6

Describe the sturucture of starch

Answer 6

• made up of only alpha glucose
• contain 1-4 & 1-6 glycosidic bonds (branched version = amylopectin)
• unbranched - amylose

Question 7

Describe the structure glycogen

Answer 7

• made up of only alpha glucose
• can be both branched and unbranched but mostly likely branched
• every 8-12 residues branch points occur

Question 8

What are
- hetropolysaccharides
- dextran
- cellulose
and describe their structures

Answer 8

1. contains 2 + different polysaccharides
2. structural component in bacteria and yeast (1-3 &1-4 glycosidic bonds)
3. beta glucose - hydrogen bonds formed making very strong

Question 9

What characterised an monosaccharides

Answer 9

polyhydroxy aldehydes

Question 10

What dos poly hydroxy mean in a molecule

Answer 10

they have a reptile number of carbon atoms with combine with hydroxyl
- structures doesn’t bind water but splits it

Question 11

What functional group is glucose

Answer 11

Poly hydroxyaldehyde

Question 12

What is the bond angle that aldehydes/ketones make with alcohols

Answer 12

• 109 degrees

Question 13

What is the importance of carbohydrates

Answer 13

• Energy storage (glucose)
• major fuel for all tissues and the SOLE fuel in the brains and RBC

Question 14

What diseases are associated with abnormal carbohydrate metabolism

Answer 14

① diabetes (mellitus)
② galactosaemia
③ fructose intolerance
④ lactose (milk) intolerance

Question 15

What is the difference between L and D glucose

Answer 15

D-glucose has OH group on right side while L-glucose has it on the left ( carbon 5)

Question 16

What is an epimer & give an example

Answer 16

Disteromers that differ only at 1 chiral centre
- D-glucose is an epimer if D-galactose

Question 17

How does glucose form from an aldehyde

Answer 17

react with a mild acid

Question 18

How can we determine the number of asymmetric carbon e.g. glucose

Answer 18

2^N
- glucose = 6 carbon
- has 4 asymmetric centres
2^4 = 16 isomers

Question 19

What is an properties of glucose

Answer 19

water soluble

Question 20

How does glucose react with alcohols

Answer 20

Organic esters with;
- acids & phosphates
- supoahets with phosphoric and sulphuric acid

Question 21

What do pentoses and hexoses cyclize to from

Answer 21

• furanose
• pyranose rings

Question 22

Why are hydrogen bonds transceint and give an example

Answer 22

• ambient temperature can break them
  e.g., we can die of hypothermia due to molecules freezing and stop moving

Question 23

What is is called when isomers aren’t micro images

Answer 23

diasteriosiomers

Question 24

How does D-glucopyranose react with alcohols

Answer 24

forms akyl ( alpha or beta) glucoppyranosides

Question 25

What is glucosamine

Answer 25

- non reducing sugar - formed via reduction of glucose

Question 26

How does a sugar lose it property to be reduced

Answer 26

- if alpha for beta molecules its engaged in covalent interaction

Question 27

What is the function of the molecule produced when glucose binds to haemoglobin

Answer 27

Diabetes blood test - measures glycosylated haemoglobin

Question 28

What are functions of modified sugars

Answer 28

- antibodies - communication - cell surfaces receptors - neurotransmission

Question 29

Why does glycogen stores itself in granules but starch is a larger gobble

Answer 29

- accessibility - metabolism in human is dates then in plants

Question 30

Why is cellulose water soluble but starch isn't

Answer 30

in cellulose there are loads more potential hydrogen bonds that can be formed

Question 31

What are glycoproteins

Answer 31

usually short ,often branched oligosaccharides covalently attached to protein backbone

Question 32

What are glycosaminoglycans

Answer 32

always repeating sequence of 2 monosaccharides one of which is an amino acid

Question 33

What is Heparin

Answer 33

- anti-clotting agent - screed by mast cells lining the wall go blond vessels , liver and lungs

Question 34

Where does glycosylation take place

Answer 34

lumen ondf ER and Golgi complex

Question 35

What does N-glycosylation involve

Answer 35

activation of oligosaccharides by binding to dolichol phosphate

Question 36

What can error in glycosylation result in

Answer 36

pathological conditons; - I-cell disease - lysosomes accumulate large amounts of glycosaminoglycans - no enzymes to digest, inspire of their abundance in the blood - due to incorrect addressing and enzyme can't be delivered to lysosome

Question 37

What are lectins

Answer 37

- universal carbohydrate recognition proteins