Cellular Energetics Pt. 2

Cellular Respiration

Glycolysis

10 step process that starts respiration

in cytosol/cytoplasm outside mitochondria

inputs: ATP, glucose

outputs: 2 pyruvate, 2 NADH, 4 ATP (net gain of 2 ATP), 2 H₂O (ALL PER ONE GLUCOSE MOLECULE)

oxygen has no role in glycolysis

aerobic process

Krebs Cycle/ Citric acid cycle

in matrix of mitochondria

inputs: acetyl-coA, NAD+, FAD, ADP

outputs: 4 NADH, 1 FADH₂ and 2 ATP

Acetyl-CoA (2C)

converted from pyruvate, produces an NADH in the process

combines with oxaloacetate (4C) to make citrate (6C) - citrate eventually loses 2 carbons in the form of CO₂ to become ocaloacetate again

Meanwhile…

3 more NAD⁺ converted to 3 NADH

ADP to ATP

FADH to FADH₂

Totals

Because TWO pyruvate originate from one glucose, one glucose molecule will yield double the outputs from the Krebs cycle in addition to glycolyis

10 NADH, 2 FADH₂, and 4 ATP

Oxidative phosphorylation

NADH and FADH₂ to create up to 34 ATP molecules from each glucose, totaling 38 from krebs + glycolysis + ETC

inner membrane of mitochondria (cristae)

Electron Transport Chain (ETC)

series of redox reactions that transfer electrons down a chain to create ATP through chemiosmosis.

oxygen final electron acceptor, forms water

chemiosmosis

coupling of the movement of electrons down ETC with the movement of protons across a membrane to generate ATP

ATP synthase

enzyme that uses the flow of hydrogens to drive phosphorylation of ADP to make ATP

anaerobic respiration/fermentation

when oxygen unavailable to use

glycolysis and krebs occuring naturally, but buildup of NADH in oxidative phosphrylation due to no oxygen

produces two net ATP

either alcohol or lactic fermentation

alcohol fermentation

2 pyruvate → 2 acetaldehyde → 2 ethanol while releasing 2 CO₂ and turning 2 NADH to 2 NAD⁺

yeast (wine, beer, bread)

lactic fermentation

pyruvate reduced directly to NADH to oxidize, no CO₂ released

muscle cramps

fungi & bacteria (cheese, yogurt)