Exam 3

Question 1

The two distinct divisions of metabolism

Answer 1

Catabolic reactions (catabolism) and anabolic reactions (anabolism)

Question 2

Catabolic Reactions (characteristics)

Answer 2

1) Breaks down complex molecules, makes them simpler. 2) releases energy. 3) DOWNHILL REACTION

Question 3

Anabolic Reactions (characteristic)

Answer 3

• links simple molecules
• makes them more complex
• require energy
• UPHILL REACTIONS

Question 4

Metabolic Pathways

Answer 4

Series of chemical reactions that happen in a cell

Question 5

Delta G

Answer 5

G (products) - G (reactants)

Question 6

Delta G in exergonic reactions

Answer 6

Negative

Question 7

Delta G in endergonic reactions

Answer 7

Positive

Question 8

Energy coupling

Answer 8

Exergonic reactions are used to drive endergonic ones

Question 9

ATP

Answer 9

Adenosine Triphosphate
“Energy currency” in cells
Powers cellular work through energy coupling

Question 10

How does the release of energy occur during the hydrolysis of ATP?”

Answer 10

The chemical change to a lower state of free energy causes energy to be released

Question 11

How do enzymes speed up metabolic reactions?

Answer 11

By lowering the activation energy barrier, making it so that the reaction to happen at moderate temperatures.

Question 12

Catalyst

Answer 12

Chemical agent that speeds up a reaction without being consumed by the reaction

Question 13

What is an enzyme?

Answer 13

A catalytic protein. (Names often end in -ase)

Question 14

What is the enzyme’s substrate?

Answer 14

The reactant that an enzyme acts on.

Question 15

What happens when the enzyme binds to its substrate?

Answer 15

Enzyme-substrate complex is created

Question 16

What happens to the enzyme when the substrate enters the active site?

Answer 16

Enzyme changes shape slightly, creating an induced fit.

Question 17

What affects enzyme activity?

Answer 17

Temperature, pH, cofactors, and inhibitors.

Question 18

Temperature’s effect on enzyme activity

Answer 18

As temperature increases, the reaction rate will also increase. Enzymes also have a peak performance at a temperature optimum, they denature beyond that temperature.

Question 19

pH’s effect on enzyme activity.

Answer 19

Most enzymes have a pH at which they perform at peak efficiency (pH optimum)

Question 20

What is a cofactor?

Answer 20

A nonprotein helper that binds to the enzyme permanently, or reversibly with the substrate

Question 21

What is a coenzyme?

Answer 21

Organic cofactors

Question 22

What are inhibitors?

Answer 22

Chemicals that selectively inhibit the action of specific enzymes

Question 23

When is inhibition usually irreversible?

Answer 23

When the inhibitor covalent bonds with the enzyme

Question 24

When does reversible inhibition happen?

Answer 24

When inhibitors bind to the enzyme by weak interactions

Question 25

Competitive inhibitors

Answer 25

Inhibitors that closely resemble the substrate and can bind to the active site

Question 26

How can you overcome competitive inhibition?

Answer 26

By increasing substrate concentration

Question 27

What are noncompetitive inhibitors?

Answer 27

Inhibitors that bind to a part of the enzyme that is away from the active site. This causes the enzyme to change shape (the active site becomes less effective)

Question 28

Allosteric Regulation

Answer 28

- Can inhibit or stimulate the enzyme's activity - Occurs when a regulatory molecule binds to a protein at one site and affects the protein's function at another site

Question 29

What is cellular respiration?

Answer 29

A catabolic pathway that breaks down organic molecules. It uses an electron transfer chain for the production of ATP