Biochemistry L04 Enzymes and Cellular Energy

Question 1

Name 3 factors that affect enzyme activity

Answer 1

Temperature
pH
Substrate concentration

Question 2

Define substrate

Answer 2

The reactant of a catalysed reaction

Question 3

Define active site

Answer 3

Site of an enzyme that binds to the substrate in a configuration that forces it to resemble the transition state. It is highly specific

Question 4

Define activation energy

Answer 4

The energy barrier that a reaction must overcome in order to occur

Question 5

What is the difference between an endergonic and exergonic reaction?

Answer 5

Energonic reactions absorb energy

Exergonic reactions release energy

Question 6

If a reaction has ΔG = -30kJ/mole, is it endergonic or exergonic?

Answer 6

Exergonic

Question 7

How does a catalyst affect ΔG, Ea (activation energy) and the equilibrium of a reaction?

Answer 7

No change in ΔG
Ea decreases
No change in equilibrium

Question 8

What is ΔG of ATP hydrolysis?

Answer 8

-29.3kJ/mol

Question 9

Name 1 molecule other than ATP that can be used as cellular energy currency (or are precursors of ATP)

Answer 9

NADH
FADH2
Acetyl CoA
GTP

Question 10

What is the transition state?

Answer 10

The intermediate state between reactant and product. The enzyme’s active site has a higher affinity for the TS than the reactant, so on reactant binding induces a conformational change in the reactant towards the TS.
The TS is the highest point of energy in the reaction