Enzymes and Kinetics

Question 1

What is free energy?

Answer 1

G; portion of system’s energy that can do work

Question 2

Less free energy equals what?

Answer 2

system in its final state is less likely to change; more stable

Question 3

Exergonic

Answer 3

Net release of free energy; spontaneous with a negative delta G (products have less energy than reactants)

Question 4

Endergonic

Answer 4

Requires input of free energy; Non-spontaneous with a positive delta G (or 0)

Question 5

Activation energy

Answer 5

initial energy needed to start a chemical reaction

Question 6

Enzymes

Answer 6

catalytic protein; lowers activation energy and is specific; lowers Ea

Question 7

Catalyst

Answer 7

selectively speeds up rxn without being consumed

Question 8

Reactant in enzyme reaction

Answer 8

Substrate

Question 9

Substrate enters active site to create…

Answer 9

Induced fit; held together by ionic and h-bonds

Question 10

Active site lowers Ea by…

Answer 10

1. orienting 2+ substrates correctly
2. straining substrate bonds-distort substrate
3. provide favorable microenvironment
4. temporary covalent bonding with substrate

Question 11

Enzyme reaction cycle steps

Answer 11

1. substrates enter active site
2. substrates are held in active site by weak interactions
3. Active site lowers Ea
4. substrates are converted to products
5. products are released
6. active site is available for new substrates

Question 12

Effects on enzyme activity

Answer 12

1, Physical and chemical conditions (temp/pH)
2. Cofactors (metal ions, vitamins, small molecules, organic molecules (coenzymes))
3. Inhibitors
4. Change in primary structure (change function)