Module 4, Lectures 1,2

Question 1

What are the four major classes of organic molecules?

Answer 1

Carbohydrates
lipids
proteins
nucleic acids

Question 2

What atoms categorize functional groups?

Answer 2

Oxygen, nitrogen, sulfur or phosphorus

Question 3

Properties of alcohols?

Answer 3

Low Molecular weight Oh are water soluble
Hydrogen bonding
Undergo nucleophilic substitution reactions
Can be oxidised
Form esters with carboxylic acids

Question 4

What can different types of alcohols be oxidised to?

Answer 4

Primary = aldehydes then carboxylic acids
secondary = Ketones
Tertiary are not readily oxidised

Question 5

What is the difference between ethers and esters?

Answer 5

Ethers may be cleaved and are generally unreactive. Esters are easily cleaved by reaction with nucleophiles.

Question 6

What is the difference between amines and amides?

Answer 6

Amines are very basic, whereas amides are not basic or nucleophilic

Question 7

Thiols?

Answer 7

Thiol groups react like alcohols - the sulfur nucleophile

Question 8

Disulfides?

Answer 8

Important reaction in organic chemistry.

Oxidation leads to disulfide that links peptide chain.

Question 9

Phosphorus containing functional groups?

Answer 9

H3PO4 forms a series of phosphate esters where the OH groups are successfully replaced.by OR groups from alcohols.

Question 10

Benefits/functions of Phosphorus containing functional groups?

Answer 10

Help to solubilise compounds in water.

Quite resistant to hydrogen bonding

Question 11

What is the concept of Biological recognition?

Answer 11

The “host” component can be considered the larger molecule, and it encompasses the smaller, “guest”, molecule.

Question 12

What factors control the shape of a host molecule?

Answer 12

Polar or non-polar internal attractions or repulsions
Steric effects - interaction of large groups avoided
Geometric constraints imposed by rigid structural vblocks

Question 13

Aldehydes Vs Ketones?

Answer 13

Aldehydes are more reactive because the C of ketones is less attractive to nucleophiles.
• Steric: less hindered for the aldehyde. Aldehydes have at least one (small) H substituent. Ketones have two bulky substituents.
• Electronic: electron donating alkyl groups reduce d+ charge on C
of C=O. Ketones have two groups, aldehydes have one.

Question 14

What is a carbonyl group/compound?

Answer 14

a carbonyl group is a functional group composed of a carbon atom double-bonded to an oxygen atom: C=OA compound containing a carbonyl group is often referred to as a carbonyl compound.

Question 15

What are hemiacetals?

Answer 15

Hemiacetals and acetals dominate chemistry of carbohydrates. Eg glucose is a hemiacetal.
Carbon is attached to two oxygen atoms, one is an OH and the other OR.

Question 16

How does a hemiacetal form?

Answer 16

When an aldehyde reacts with an alcohol.

Question 17

What are acetals, and how are they formed?

Answer 17

Acetals are geminal-diether derivatives of aldehydes or ketones, formed by reaction with two equivalents (or an excess amount) of an alcohol and elimination of water.

Question 18

What are imines and how are they formed?

Answer 18

Imines are the nitrogen analogues of aldehydes and ketones, containing a C=N bond instead of a C=O. bond. They are formed through the dehydration reaction of an aldehyde or ketone with an amine

Question 19

Briefly describe the chemistry of vision?

Answer 19

Reversible attach compounds to proteins (eg retinal and opsin).
Different opsins give different photoreceptors optimal for different colours.
Isomerisation triggers a cascade of events that sends signal from the eye to brain.
Once this occurs photoreceptor is no longer active. the spent chromosome is exchanged for a fresh one and the imine link allows chromosome to be released.