Chemical Energy (5/1/26)

Energy

• Definition

• Definition: The ability/capacity to create change

Kinetic energy

• Definition

• Definition: Energy associated with random molecular motion

Catabolic reactions

1. What do they release?

2. What are some examples (give 3)

1. They release energy

2. Examples: Glycolysis, the citric acid cycle, oxidative phosphorylation

Potential energy

• Definition

• Where is it stored?

• Definition: Energy that is stored but not yet released

• It can be stored in bonds, or across diffusion gradients

Activation energy

• Definition

• What are the three requirements for a chemical reaction to occur?

• Definition: The initial input of energy needed to release stored energy or cause a chemical reaction

• (1) Molecules are moving with enough kinetic energy, (2) Molecules are in the correct orientation, (3) The molecules contain the necessary components (such as substrates, catalysts, functional groups, etc).

Enzymes

1. Definition

2. Enzymes do not… (2)

3. Enzymes reduce… (1)

4. Enzymes are usually… (1)

5. Enzymes depend on… (1)

6. Enzymes are affected by… (3)

7. Enzymes are not always… (1)

1. Proteins that lower activation energy by holding molecules in the correct position

2. Enzymes do not (1) eliminate the need for energy, or (2) make exothermic reactions into endothermic reactions

3. Enzymes reduce the amount of activation energy needed

4. Enzymes are usually proteins

5. Enzymes depend on their shape to function

6. Enzymes are affected by temperature, pH, and genetic mutations

7. Enzymes are not always active.

How do cells activate / deactivate enzymes?

Cells have “on/off switches,” often involving phosphate groups. When ATP releases a phosphate group, it can change the shape and activity of an enzyme/protein.