Recap of Fermentations

Glucose -> 2 pyruvate + 2 ATP + 2 NADH

2 pyruvate + 2 NADH -> 2 lactate

2 pyruvate + 2 NADH -> 2 ethanol + 2 CO2

First part of glycolysis:

Completing the fermentation:

Lactic fermentation

Ethanolic fermentation

Recap of Fermentations, cont.

pyruvate -> acetate + ATP + HCOOH (phosphoroclastic rxn)

pyruvate + 2 NADH -> ethanol + HCOOH

Completing the fermentation:

Mixed acid fermentation

HCOOH -> H2 + CO2 (under acidic conditions)

This fermentation can also include production of succinate, lactate, or butylene glycol

2 pyruvate + 2 NADH -> CH3CHOHCHOHCH3 + HCOOH + CO2

Respiration

Aerobic Respiration

• In aerobic respiration, O2 is the terminal electron acceptor

• Energy is captured by electron transport– NAD reduction (NADH dehydrogenases)– Flavoproteins– Iron-sulfur proteins– cytochromes

Flavine mononucleotide (FMN)

Heme prosthetic group

Cytochrome with heme

Iron-sulfur proteins (Fe2S2)

Iron-sulfur protein (Fe4S4)

Quinones (coenzyme Q)

Membrane localization of electron carriers

NDH: NAD dehydrogenase

Flavoprotein (H and e)

NHFe (non-heme iron-sulfur), e only

Q: coenzyme Q (H and e)

Cytochromes (e only)

ATPase

Citric acid cycle

• Pyruvate is oxidatively (NADH) cleaved to acetyl-CoA plus CO2 (refer to page 127)– Acetyl-CoA is a 2-carbon fragment (acetate) bound to a

carrier (membrane-insoluble)

• 1 acetate is oxidized with each pass around the cycle, generating 4 pairs of electrons (2 NADH, 1 NADPH, and 1 FADH2) and 1 GTP

• The 4 electron-pairs can be passed to the electron-transport chain

Acetyl coenzyme A

Electron Transport from NADH, FADH2

Energy Balance Sheet

• Fermentation: 2 or 3 ATP per glucose• Respiration, glycolysis:

– Glucose -> 2 pyruvate + 2 NADH + 2 ATP– 2 NADH -> 6 ATP

• Respiration, citric-acid cycle:– 2 pyruvate -> 8 NADH + 2 FADH2 + 2 GTP– 8 NADH (from acetate) -> 24 ATP– 2 FADH2 -> 4 ATP

• Respiration, total: 38 ATP per mole of glucose

Aerobic Respiration

Anaerobic Respiration

Chemolithotrophic respiration

Phototrophic metabolism