Lecture 8

Question 1

Why are biological systems not good for doing chemistry? What molecule exists to help with this?

Answer 1

Limited to one solvent (H2O), low temperatures and near neutral pH most of the time. Enzymes help to make it easier to perform reactions.

Question 2

How do enzymes increase the ability for reactions to occur and what are key things to keep in mind?

Answer 2

enzymes decrease the free energy of activation and accelerate the forward and reverse reactions equally. Most are made out of protein, but some are made out of RNA(very very few) too. They do not change the equilibrium of a reaction, do not change how thermodynamically favourable a reaction is, they may also follow a similar reaction sequence as chemically catalysed reactions (but in a different way).

Question 3

Why do enzyme catalyzed rates fall within a narrower range than uncatalysed?

Answer 3

The chemical pathway can only go as fast as the slowest rate, hence keeping the rates at roughly the same is important.

Question 4

What are the classes of enzymes?

Answer 4

1. oxidoreducatses: transfer of electrons
2. transferases: group-transfer reactions
3. Hydrolases: hydrolysis reactions
4. Lyases: addition of groups to double bonds or the reverse
5. Isomerases: Transfer of groups within molecules to yield isomeric forms
6. Ligases: formation of C-C, C-S, C-O and C-N bonds by condensation reactions coupled to ATP cleavage.

Question 5

What are the four parts to an EC number in order?

Answer 5

A.B.C.D
A: the class
B. the sub class, what its class does specifically
C. Sub sub-class, what group it acts on
D. serial number, the specific molecule it acts on.
All of these will be numbers.