Lecture 3 - Metabolism & Energy

What are adhesion junctions?

They mechanically connect cells.

What is the function of tight junctions?

They form barriers with the external environment.

What is the purpose of gap junctions?

They allow direct communication between cells.

What is metabolism?

The sum of all chemical reactions that occur within a given body.

What are enzymes?

Biochemical catalysts, usually made of protein, speed up reactions.

What are metabolic pathways?

A series of linked chemical reactions that occur within a cell.

What is degradation in metabolism?

A substrate is broken down into smaller products.

What is synthesis in metabolism?

Substrates are combined to produce a larger product.

What is a coenzyme?

A nonprotein molecule that assists enzyme activity and may accept or contribute atoms.

What is NAD+?

An example of a coenzyme that carries hydrogen and electrons.

What are mitochondria?

Double membrane-bound organelles that convert glucose to ATP via cellular respiration.

What happens during glycolysis?

Glucose (6-carbon) is split into two pyruvate (3-carbon) molecules in an anaerobic process.

How much ATP does glycolysis produce?

Consumes 2 ATP, produces 4 ATP, for a net gain of 2 ATP.

What else is produced in glycolysis besides ATP?

2 NAD+ molecules.

What happens in the citric acid cycle (Krebs cycle)?

Breaks down remaining C-C bonds in pyruvate (acetyl CoA), produces 2 ATP per glucose, and generates NADH and FADH2.

What is the electron transport chain (ETC)?

An aerobic process that uses NADH and FADH2 to generate 25-38 ATP; most efficient part of cellular respiration.

What is fermentation?

An anaerobic process for cellular metabolism that does not utilize the citric acid cycle or the electron transport chain. Producing 2 ATP per glucose; forms lactate in animals or ethanol and CO2 in yeast.

What is an anaerobic process?

A process that does not require oxygen.

What is an aerobic process?

A process that requires oxygen for efficient ATP production.

What is ATP?

Adenosine triphosphate, the main energy currency of the cell.