AP BIO CH 7 (unit 6)

What is cellular respiration?

A catabolic process that breaks down organic molecules like glucose to make ATP, releasing stored energy.

What is the primary purpose of cellular respiration?

To convert energy stored in organic molecules into ATP.

What type of reactions are involved in cellular respiration?

Redox reactions, involving oxidation (loss of electrons) and reduction (gain of electrons).

What is oxidized in cellular respiration?

Glucose is oxidized during the process.

What is the role of NADH in cellular respiration?

NADH serves as an electron carrier, yielding more ATP than FADH2.

What are the three major pathways of cellular respiration?

1. Glycolysis 2. Krebs Cycle (Citric Acid Cycle) 3. Electron Transport Chain (ETC)

Where does glycolysis occur?

In the cytoplasm (cytosol).

What is produced during glycolysis?

4 ATP (net gain of 2 ATP), 2 NADH, and 2 pyruvate molecules.

What happens during pyruvate oxidation?

Pyruvate is converted into Acetyl CoA, producing NADH and releasing CO2.

Where does the Krebs Cycle take place?

In the mitochondrial matrix.

What are the products of one turn of the Krebs Cycle?

3 NADH, 1 ATP, 1 FADH2, and 2 CO2.

What is the function of the Electron Transport Chain?

To create an electrochemical gradient that drives ATP synthesis through chemiosmosis.

What is chemiosmosis?

The process of using a proton gradient to synthesize ATP.

Key component of the ETC (electron carriers)

Flavoprotein (1st molecule of ETC), ubiquinone (only non-protein and individually mobile and small and hydrophobic), cytochromes (majority of the ETC, has a heme prosthetic group)

proton motive force (PMF)

a source of energy resulting from the separation of protons across the cytoplasmic membrane, generating a membrane potential

What is the efficiency of glucose energy captured as ATP?

About 34% of glucose energy is captured as ATP; the rest is lost as heat.

What is fermentation?

An anaerobic process that regenerates NAD+ so glycolysis can continue, but does not produce ATP directly.

What are the two types of fermentation?

1. Lactic acid fermentation (in animals) 2. Alcohol fermentation (in yeast and some bacteria).

What is produced during lactic acid fermentation?

Lactate is produced when pyruvate is reduced by NADH.

What is the main cause of muscle fatigue during exercise?

Lactate accumulation is responsible for muscle fatigue, not lactate itself.

What is the role of facultative anaerobes?

They can switch between fermentation and aerobic respiration based on oxygen availability.

What is the significance of obligate anaerobes?

They perform only fermentation and cannot survive in the presence of oxygen.

What is the role of coenzyme A in cellular respiration?

Coenzyme A is added to Acetyl CoA during pyruvate oxidation.

What is the difference between NADH and FADH2 in terms of ATP yield?

NADH yields approximately 2.5 ATP, while FADH2 yields about 1.5 ATP.

Process of lactic acid fermentation

Pyruvate directly reduced by NADH, no CO2 released

Alcohol fermentation process

Pyruvate oxidized into acetaldehyde + co2 (waste), then acetaldehyde reduced to ethanol by NADH , (CO2 released)