Carbohydrates and alcohols

Question 1

Why is it difficult to develop effective antibodies against HIV?

Answer 1

Glycoprotein 120 which is found on the surface of HIV and which binds to T-cells is constantly changing shape

Question 2

What is the typical pK_a value of alcohols?

Answer 2

around 15-17

Question 3

What functional groups are present in a carbohydrate?

Answer 3

Carbonyl and hydroxyl

Question 4

How can an alcohol be made reactive?

Answer 4

Set up a local environment to stabilise the conjugate base

Question 5

Give an example of alcohols acting as a nucleophile in biology?

Answer 5

In serine proteases

Question 6

Give an example of an enzyme which can oxidise an alcohol to an aldehyde

Answer 6

Alcohol dehydrogenase

Question 7

What cofactor is required in the oxidation of alcohol to an aldehyde?

Answer 7

NAD+

Question 8

Phosphorylation of which amino acid groups is central to signalling?

Answer 8

Serine and tyrosine

Question 9

What is a ketose?

Answer 9

A sugar which contains a ketone functional group

Question 10

What is an aldose?

Answer 10

A sugar which contains an aldehyde group

Question 11

What type of reaction typically modifies hydroxyl groups?

Answer 11

Nucleophilic substitution

Question 12

What are the 2 forms 6 carbon sugars can form?

Answer 12

Pyranose and furanose

Question 13

Describe the basic structure of a pyranose

Answer 13

A 6 membered cyclic structure

Question 14

Describe the basic structure of a furanose

Answer 14

A five membered cyclic structure

Question 15

Why is glucose found in a pyranose formation 99% of the time?

Answer 15

The 6 membered ring has less torsional strain and is energetically preferred

Question 16

Which conformation of pyranose is the most stable and thus the most common?

Answer 16

Chair

Question 17

Can alcohols form hydrogen bonds?

Answer 17

Yes

Question 18

What are the 3 different conformations pyranose can form?

Answer 18

Chair, half chair, and boat

Question 19

Which direction does C6 almost always point?

Answer 19

Upwards

Question 20

What 3 amino acids make up the catalytic triad?

Answer 20

• Serine
• Histidine
• Aspartic acid

Question 21

What % of glucose is found in the D-glucose form?

Answer 21

0.02%

Question 22

What % of glucose is found in the furanose form?

Answer 22

<0.2%

Question 23

What % of glucose is found in the pyranose form?

Answer 23

99.8%