BIO2000 - Chapter 7: Cellular Respiration and Fermentation

cellular respiration

Process by which living cells obtain energy from organic molecules and release waste products; Primary aim to make ATP

glycolysis

Glucose is broken down to two pyruvate molecules; producing 2 ATP and 2 NADH molecules; Occurs in the cytosol in eukaryotes

Substrate level phosphorylation

occurs when an enzyme transfers a phosphate from a phosphorylated organic molecule to ADP

Breakdown of pyruvate

occurs in the mitochondrial matrix in eukaryotes; Each pyruvate is broken down to an acetyl group and CO2 - one NADH is generated per pyruvate

citric acid cycle

Each acetyl group is incorporated into an organic molecule; later oxidized to liberate two CO2 molecules; Occurs in the mitochondrial matrix; total yield is 4 CO2, 2 ATP, 6 NADH, 2 FADH2

Oxidative phosphorylation

NADH and 2 FADH2 from previous steps contain high energy electrons; energy is harnessed to produce an H+ electrochemical gradient; During chemiosmosis energy stored in the gradient is used to synthesize ATP; Occurs in the cristae in eukaryotes; 30-34 ATP molecules made in oxidative phosphorylation

biochemistry

study of the chemistry of living organisms

Energy investment phase of glycolsis

Steps 1 to 3; 2 ATP hydrolyzed to create fructose-1,6 bisphosphate

cleave phase of glycolysis

steps 4 to 5; 6 carbon molecules broken into two 3 carbon molecules of glyceraldehyde-3-phosphate

energy liberation phase of glycolysis

steps 6 to 10; Two glyceraldehyde-3-phosphate molecules broken down into two pyruvate molecules – produces 2 NADH and 4 ATP (net yield = 2 ATP)

Warburg effect

cancer cells preferentially use glycolysis for ATP production in contrast to healthy cells, which use oxidative phosphorylation

Breakdown of Pyruvate

In eukaryotes, pyruvate is transported into the mitochondrial matrix; Broken down by pyruvate dehydrogenase; Molecule of CO2 removed from each pyruvate; Remaining acetyl group attached to CoA to make acetyl CoA; Yield = 1 NADH for each pyruvate

ATP synthase

captures free energy as H+ ions flow through

Besides glucose, other molecules also used for energy

carbohydrates, proteins, fats; Enter into glycolysis or citric acid cycle at different points; Utilizing the same pathways for breakdown increases efficiency

Anerobic

describes an environment that lacks oxygen

Fermentation

the breakdown of organic molecules without net oxidation