Enzymes and Kinetics

Question 1

What is free energy (G)?

Answer 1

Portion of a system’s energy that can do work.

Question 2

What does it mean if a system in its final state has less free energy?

Answer 2

More stable

Question 3

What is the equation for free energy?

Answer 3

G(final) - G(initial)

Question 4

If the overall change of G is ____ it is a spontaneous change.

Answer 4

Negative

Question 5

What is an exergonic reaction?

Answer 5

Net release of energy

Question 6

What is an endergonic reaction?

Answer 6

Net input of energy

Question 7

What is the name of the state where bond breaking and bond forming occurs?

Answer 7

Transition state

Question 8

Intitial energy needed to start chemical reactions is called what?

Answer 8

Activation Energy

Question 9

How do cells handle thermal energy?

Answer 9

Denature if too high or speed up all reactions spontaneously

Question 10

What is a catalyst?

Answer 10

Selectively speeds up reactions without being consumed by the reaction

Question 11

What is an enzyme?

Answer 11

Catalytic protein that lowers the activation energy of a reaction

Question 12

Does adding an enzyme change the free energy (G)?

Answer 12

NO

Question 13

What is the name of the reactant used by enzymes?

Answer 13

Substrate

Question 14

What is the active site?

Answer 14

Place where the substrate binds to the enzyme and the reaction occurs

Question 15

What are the type of bonds in an active site?

Answer 15

Ionic or H-bonding

Question 16

What is induced fit?

Answer 16

Conformational change to grab onto substrate

Question 17

What is the name of the structure that contains both an enzyme and substrate?

Answer 17

Enzyme-substrate complex

Question 18

How does an active site lower activation energy? (4)

Answer 18

1. orienting 2+ substrates correctly
2. Straining substrate bonds- distorts substrate
3. Providing favorable microenvirnoments
4. Temporary covalent bonding with the substrate

Question 19

True or false… Enzymes change in a reaction

Answer 19

FALSE

Question 20

How do you increase the rate of reactions in enzymes?

Answer 20

Increase the concentration

Question 21

What does it mean if a enzyme is saturated?

Answer 21

All the enzyme molecules have active sites in use

Question 22

How do you reduce saturation?

Answer 22

Add more enzymes to an area

Question 23

What can effect enzyme activity? Define or give example of each

Answer 23

1. Physical and chemical conditions- temerature and pH
2. Cofactors- promote function- Metal ions, vitamins, small molecules
3. Inhibitors- block function of enzyme
4. Change primary structure- alter the sequence of the amino acids

Question 24

What are competitive inhibitors?

Answer 24

Compete for substrate bonding site

Question 25

What are noncompetitive inhibitors?

Answer 25

Do not bind to the active site but will change the shape of the acitve site to stop function.

Question 26

What is the order of an enzyme cycle? (6)

Answer 26

1. Substrate enters active site
2. Substrates are held in active site by weak interactions
3. The active site lowers Ea
4. Substrates are converted to products
5. Products are released
6. Active site now available for new substrate