Chapter 2.1

Question 1

Do catalysts affect the enthalpy of a reaction, equilibrium constant of a reaction or the gibbs free energy change

Answer 1

-no

Question 2

What are oxidoreductases responsible for? Name examples

Answer 2

• they are involved in oxidation/reduction reactions
• > transfer of electrons between biological molecules
• > often have a cofactor that acts as an electron carrier
• electron donor is the reductant
• electron acceptor is known as the oxidant

-dehydrogenase, reductase and oxidase are examples

Question 3

What are transferases responsible for? Give examples

Answer 3

• transfer the movement of a functional group
• > from one group to another

eg; kinases
->they transfer a phosphate group from one molecule to another

Question 4

What are hydrolases? Give examples

Answer 4

• catalyze the breaking of a compound
• > into two molecules
• > using the addition of water
• > eg; phosphatase, peptidases, nucleases and lipases

Question 5

What are lyases? Can they reverse the breakdown of their reactions?

Answer 5

• catalyze the cleavage of a single molecule into two products
• > do not require water as a substrate
• > do not act as oxidoreductases
• they can also catalyze the reverse of reaction
• > so make a single molecule from two reactants
• > in this case, the lyase becomes a SYNTHASE

-generally for synthesis, they create smaller molecules than ligases

Question 6

What are isomerases?

Answer 6

• they just rearrange bonds within a molecule
• > can be classified as oxidoreductases, transferases, lyases
• > depends on the mechanism of the reaction

Question 7

What are ligases? What important molecule do they require for these reactions?

Answer 7

• they catalyze addition or synthesis reactions
• > generally between large molecules
• > often require ATP

-most likely to be encountered in nucleic acid synthesis

Question 8

Can enzymes affect how fast a reaction reaches equilibrium

Answer 8

• yes

- >but they do not equilibrium itself