Cellular Respiration

U3 ap bio

Glycolysis (Occurs in the cytoplasm)

Glucose (6C) is broken into two pyruvate (3C). Glucose is oxidized to pyruvate, and NAD+ is reduced to NADH.

Reactants of Glycolysis

Glucose, 2 ATP, NAD+.

Products of Glycolysis

2 Pyruvate, 4 ATP (net gain of 2), 2 NADH.

ATP Production in Glycolysis

2 ATP (via substrate-level phosphorylation).

Electron Transfer in Glycolysis

NAD+ is reduced to NADH.

Pyruvate Oxidation (Link Reaction) (Occurs in the mitochondrial matrix)

Pyruvate is converted into Acetyl-CoA. Pyruvate is oxidized to Acetyl-CoA, and NAD+ is reduced to NADH.

Reactants of Pyruvate Oxidation

Pyruvate, NAD+, Coenzyme A.

Products of Pyruvate Oxidation

Acetyl-CoA, CO2, NADH.

Electron Transfer in Pyruvate Oxidation

NAD+ is reduced to NADH.

Krebs Cycle (Citric Acid Cycle) (Occurs in the mitochondrial matrix)

Acetyl-CoA is broken down to extract high-energy electrons. Acetyl-CoA is oxidized to CO2, while NAD+ and FAD are reduced to NADH and FADH2

Reactants of Krebs Cycle

Acetyl-CoA, NAD+, FAD, ADP.

Products of Krebs Cycle

CO2, NADH, FADH2, ATP.

ATP Production in Krebs Cycle

2 ATP (via substrate-level phosphorylation).

Electron Transfer in Krebs Cycle

NAD+ and FAD are reduced to NADH and FADH2.

Electron Transport Chain (ETC) & Chemiosmosis (Occurs in the inner mitochondrial membrane)

NADH and FADH2 donate electrons to the ETC, generating ATP via ATP synthase. NADH and FADH2 are oxidized to NAD+ and FAD, while oxygen is reduced to water

Reactants of ETC

NADH, FADH2, O2, ADP.

Products of ETC

ATP, H2O.

ATP Production in ETC

~32 ATP.

Electron Transfer in ETC

Oxygen is the final electron acceptor, reduced to H2O.

Aerobic Respiration

Requires O2, yielding ~36 ATP.

Anaerobic Respiration

Occurs without O2, leading to fermentation.

Lactic Acid Fermentation (Occurs in muscle cells, some bacteria)

Pyruvate is converted to lactic acid.

Electron Transfer in Lactic Acid Fermentation

NADH is oxidized to NAD+.

Alcoholic Fermentation (Occurs in yeast)

Pyruvate is converted to ethanol and CO2.

Electron Transfer in Alcoholic Fermentation

NADH is oxidized to NAD+.

ATP Yield in Anaerobic Respiration

2 ATP (only from glycolysis).

Substrate-Level Phosphorylation (Occurs in Glycolysis & Krebs Cycle)

Direct transfer of a phosphate group to ADP to form ATP.

Oxidative Phosphorylation (Occurs in the inner mitochondrial membrane during ETC)

ATP production using the energy released by the ETC to drive chemiosmosis.

Cellular Respiration in Prokaryotes vs Eukaryotes

Prokaryotes perform glycolysis, Krebs cycle, and ETC in the cytoplasm & plasma membrane, while eukaryotes perform glycolysis in the cytoplasm, Krebs in the mitochondria matrix, and ETC in the mitochondrial membrane (mainly in inner membrane).

Electron Carriers

NADH & FADH2 transport high-energy electrons to the ETC.

Purpose of Embedded Proteins in ETC

Facilitate electron transfer and create a proton gradient.

Chemiosmosis

The movement of protons down their gradient through ATP synthase to generate ATP.

Purpose of ATP Synthase

Uses the proton gradient to synthesize ATP.

Catabolic Pathways

Break down molecules (e.g., cellular respiration).

Anabolic Pathways

Build molecules (e.g., photosynthesis).

Oxidation

Loss of electrons (or hydrogen).

Reduction

Gain of electrons (or hydrogen).

Coupling Reactions

Exergonic reactions (energy-releasing) drive endergonic reactions (energy-consuming).

Redox Reactions

Transfer of electrons between molecules, playing a key role in energy transfer.

Alcoholic Fermentation

anaerobic respiration; form of fermentation (that produces ethyl alcohol) used by yeast and some plants, and produced carbon dioxide and is not reversible

Lactic acid fermentation

anaerobic respiration; type of fermentation that is reversible and produces lactate/lactic acid

What is oxidized in Pyruvate Oxidation?

Pyruvate is oxidized to Acetyl-CoA

What is reduced in Pyruvate Oxidation?

NAD+ is reduced to NADH

What is oxidized in Glycolysis?

Glucose is oxidized to pyruvate

What is reduced in Glycolysis?

NAD+ is reduced to NADH

What is oxidized in Krebs Cycle?

Acetyl-CoA is oxidized to CO2

What is reduced in Krebs Cycle?

NAD+ and FAD are reduced to NADH and FADH2

What is oxidized in ETC

NADH and FADH2 are oxidized to NAD+ and FAD

What is reduced in ETC

Oxygen is reduced to water

Sign that something is oxidized

no more hydrogens + less energy stored (bc more reduced molecules (aka more H) have more energy)

Non-Oxidative Phosphorylation

ATP production that does not involve oxygen, primarily through substrate-level phosphorylation in glycolysis and the Krebs cycle