Overview of Cellular Respiration

Cellular Respiration

Cells harvest chemical energy stored in organic molecules and use it to generate ATP.

Starch

The major source of fuel for animals, which breaks down into glucose.

OIL RIG

A mnemonic for oxidation is loss, reduction is gain.

C6H12O6 + 6O2

The chemical equation for the catabolic breakdown of glucose.

Energy Harvest

Glucose is broken down in steps to harvest energy, with electrons taken from glucose at different steps.

Dehydrogenases

Enzymes that take 2 electrons and 2 protons from glucose.

NAD+

The oxidizing agent for glucose that transfers electrons and protons to form NADH.

Electron Transport Chain (ETC)

A sequence of membrane proteins that shuttle electrons down a series of redox reactions, releasing energy used to make ATP.

Stages of Cellular Respiration

There are three stages: Glycolysis, Pyruvate oxidation and the citric acid cycle, and Oxidative phosphorylation.

Glycolysis

The starting point of cellular respiration that occurs in the cytosol and splits glucose into 2 pyruvates.

Energy Investment Stage

The stage in glycolysis where the cell uses ATP to phosphorylate compounds of glucose.

Energy Payoff Stage

The stage in glycolysis where energy is produced by substrate level phosphorylation.

Net Energy Yield per 1 Glucose

2 ATP and 2 NADH.

Pyruvate Oxidation

If oxygen is present, pyruvate enters the mitochondria and is oxidized into acetyl coA.

Citric Acid Cycle

Also known as the Krebs cycle, it occurs in the mitochondrial matrix and turns acetyl CoA into citrate, releasing CO2 and synthesizing ATP.

Inputs of Citric Acid Cycle

2 acetyl CoA.

Outputs of Citric Acid Cycle

2 ATP, 6 NADH, 4 CO2, and 2 FADH2.

Oxidative Phosphorylation

Consists of the electron transport chain and chemiosmosis.

ATP Synthase

The enzyme that makes ATP from ADP + P using energy from the H+ gradient across the membrane.

Proton Gradient

Formed across the inner mitochondrial membrane by the exergonic flow of electrons from NADH and FADH2.

Anaerobic Respiration

Generates ATP using an ETC in the absence of oxygen, taking place in prokaryotic organisms.

Fermentation

Generates ATP without an ETC, recycles NAD+, and occurs in the cytosol without oxygen.

Alcohol Fermentation

Pyruvate is converted into ethanol, occurring in bacteria and yeast.

Lactic Acid Fermentation

Pyruvate is reduced directly by NADH to form lactate, occurring in muscle cells.

Lactic Acidosis

A condition that can occur if lactate builds up and is unable to be broken down, leading to excessively low blood pH.