Week 2 - Enzymes

Question 1

First Law of Thermodynamics

Answer 1

Energy cannot be created or destroyed, only transformed.

Question 2

Second Law of Thermodynamics

Answer 2

Entropy (disorder) of the universe tends to increase.

Question 3

Kinetic Energy

Answer 3

Energy of motion.

Question 4

Potential Energy

Answer 4

Stored energy (e.g., chemical bonds, gradients).

Question 5

Chemical Energy

Answer 5

A form of potential energy stored in chemical bonds.

Question 6

Gibbs Free Energy (ΔG)

Answer 6

Energy available to do work.

Question 7

ΔG < 0

Answer 7

spontaneous (exergonic)

Question 8

ΔG > 0

Answer 8

non-spontaneous (endergonic)

Question 9

ATP

Answer 9

The cell’s energy currency; releases energy when hydrolyzed.

Question 10

Enthalpy (ΔH)

Answer 10

Total energy of a system (heat content).

Question 11

Entropy (ΔS)

Answer 11

Measure of disorder or randomness.

Question 12

Spontaneity

Answer 12

Whether a reaction happens without input (depends on ΔG).

Question 13

Exergonic

Answer 13

Releases free energy (ΔG < 0); spontaneous.

Question 14

Endergonic

Answer 14

Requires energy input (ΔG > 0); not spontaneous.

Question 15

Exothermic

Answer 15

Releases heat (ΔH < 0).

Question 16

Endothermic

Answer 16

Absorbs heat (ΔH > 0).

Question 17

ΔG

Answer 17

Change in Gibbs Free Energy; predicts direction of a reaction.

Question 18

Enzyme

Answer 18

A protein catalyst that speeds up chemical reactions.

Question 19

Substrate

Answer 19

The reactant that binds to the enzyme.

Question 20

Substrate Saturation

Answer 20

When all enzyme active sites are full; adding more substrate doesn’t increase rate.

Question 21

Activation Energy

Answer 21

Energy required to start a reaction.

Question 22

Transition State

Answer 22

A high-energy, unstable state during a reaction.

Question 23

Active Site

Answer 23

The part of the enzyme where the substrate binds.

Question 24

Cofactor

Answer 24

A non-protein helper (usually metal ions).

Question 25

Coenzyme

Answer 25

An organic cofactor, often a vitamin derivative (e.g., NAD⁺, FAD).

Question 26

Catalyst

Answer 26

Speeds up a reaction without being consumed.

Question 27

Competitive Inhibition

Answer 27

Inhibitor binds to active site; competes with substrate.

Question 28

Noncompetitive Inhibition

Answer 28

Inhibitor binds elsewhere, changing enzyme shape.

Question 29

Km

Answer 29

Substrate concentration at which the reaction rate is half of Vmax; measures affinity.

Question 30

Vmax

Answer 30

Maximum rate of enzyme-catalyzed reaction.

Question 31

Binding Affinity

Answer 31

Strength of substrate binding to enzyme; low Km = high affinity.

Question 32

Kinases

Answer 32

Add phosphate groups.

Question 33

Phosphatases

Answer 33

Remove phosphate groups.

Question 34

Carboxylases

Answer 34

Add carboxyl groups (–COOH).

Question 35

Decarboxylases

Answer 35

Remove CO₂.

Question 36

Oxidoreductases

Answer 36

Catalyze redox reactions (transfer of electrons).

Question 37

Hydrogenases

Answer 37

Add or remove hydrogen atoms.

Question 38

Dehydrogenases

Answer 38

Remove hydrogen (often transfer electrons to NAD⁺/FAD).

Question 39

Isomerases

Answer 39

Rearrange atoms within a molecule to form isomers.

Question 40

Energetic Coupling

Answer 40

Using an exergonic reaction (like ATP hydrolysis) to drive an endergonic one.

Question 41

Specificity

Answer 41

The ability of an enzyme to selectively bind and act on one specific substrate.

Question 42

Hydrolysis

Answer 42

A reaction that uses water to break bonds, like ATP → ADP + Pi.