ap bio 3.1 - 3.5

Enzymes

Catalytic proteins that speed up biological reactions by lowering the activation energy ($E_a$) without altering the change in free energy ($\Delta G$).

Induced fit

The structural adjustment of an enzyme's active site around a substrate to form a tight enzyme-substrate complex.

Endergonic reaction

A metabolic process that absorbs free energy from its surroundings, resulting in a positive change in free energy ($\Delta G > 0$).

Exergonic reaction

A metabolic process that releases free energy into its surroundings, resulting in a negative change in free energy ($\Delta G < 0$).

Denaturation

The structural breakdown of a protein caused by environmental stress like extreme pH or temperature, disrupting hydrogen bonds and inactivating the protein.

Competitive inhibitor

A molecule that binds directly to the active site of an enzyme, competing with the substrate for binding.

Noncompetitive (allosteric) inhibitor

A molecule that binds to a regulatory site outside the active site, altering enzyme conformation and lowering catalytic activity.

Feedback inhibition

A regulatory pathway mechanism where the final metabolic product inhibits an early enzyme to regulate synthesis and maintain homeostasis.

First Law of Thermodynamics

The law stating that energy can be transferred and transformed, but cannot be created or destroyed.

Second Law of Thermodynamics

The law stating that every energy transfer or transformation increases the total entropy of the universe.

Energy coupling

The cellular strategy of using energy released from an exergonic reaction, such as ATP hydrolysis, to drive an endergonic process.

Overall reaction equation for photosynthesis

$$6\text{CO}_2 + 6\text{H}_2\text{O} + \text{Light} \rightarrow \text{C}_6\text{H}_{12}\text{O}_6 + 6\text{O}_2$$

Photolysis

The splitting of water molecules by light energy during the light-dependent reactions to produce oxygen, protons, and electrons.

Site of the light reactions in chloroplasts

Thylakoid membrane

Site of the Calvin cycle in chloroplasts

Stroma

Net products of glycolysis per glucose molecule

$2\,\text{pyruvate}$, $2\,\text{ATP}$ (net), and $2\,\text{NADH}$

Final electron acceptor in aerobic respiration

Oxygen ($\text{O}_2$)

Primary function of fermentation

To regenerate $\text{NAD}^+$ from $\text{NADH}$ in the absence of oxygen, allowing glycolysis to continue generating ATP.