Lecture 9 - enzymes are essential for life

Question 1

if Gibbs energy is less than 0 will the reaction be spontaneous or non spontaneous

Answer 1

spontaneous, energy released

Question 2

if Gibbs energy is greater than 0 will the reaction be spontaneous or non spontaneous

Answer 2

non spontaneous, energy required

Question 3

what occurs when gibbs energy is 0

Answer 3

at equilibrium, can’t do work

Question 4

how do enzymes catalyse thermodynamically favourable reactions

Answer 4

by lowering the activation energy

Question 5

what are the classes on enzymes and their functions (6)

Answer 5

oxidoreductases = redox (i.e transfer of electrons

transferases = transfer of a functional group

hydrolases = hydrolysis reactions (using H20)

lyases = non-hydrolytic breaking or making bonds (NOT using H20)

isomerases = transfer of atoms/groups within a molecule to yield an isometric form (one steroisomer to another)

ligases = join two molecules together

Question 6

what are the two classes of co factors

Answer 6

metal ions
coenzymes

Question 7

what do cofactors do

Answer 7

help some enzymes to catalyse reactions

Question 8

what are metal ions and what do they do

Answer 8

lewis acids (electron acceptors)
- form coordination compounds with precise geometries

Question 9

what are coenzymes and what do they do

Answer 9

small organic molecules, co substrates
- carriers (of electrons, atoms or functional groups)