Recap of Fermentations

1
Recap of Fermentations
First part of glycolysis
Glucose -gt 2 pyruvate 2 ATP 2 NADH
Completing the fermentation
Lactic fermentation
2 pyruvate 2 NADH -gt 2 lactate
Ethanolic fermentation
2 pyruvate 2 NADH -gt 2 ethanol 2 CO2
2
Recap of Fermentations, cont.
Completing the fermentation
Mixed acid fermentation
pyruvate -gt acetate ATP HCOOH
(phosphoroclastic rxn)
pyruvate 2 NADH -gt ethanol HCOOH
HCOOH -gt H2 CO2 (under acidic conditions)
This fermentation can also include production of
succinate, lactate, or butylene glycol
2 pyruvate 2 NADH -gt CH3CHOHCHOHCH3 HCOOH
CO2
3
Respiration
4
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

5
Flavine mononucleotide (FMN)
6
Heme prosthetic group
7
Cytochrome with heme
8
Iron-sulfur proteins (Fe2S2)
9
Iron-sulfur protein (Fe4S4)
10
Quinones (coenzyme Q)
11
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)
12
ATPase
13
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

14
Acetyl coenzyme A
15
Electron Transport from NADH, FADH2
16
Energy Balance Sheet

• Fermentation 2 or 3 ATP per glucose
• Respiration, glycolysis
• Glucose -gt 2 pyruvate 2 NADH 2 ATP
• 2 NADH -gt 6 ATP
• Respiration, citric-acid cycle
• 2 pyruvate -gt 8 NADH 2 FADH2 2 GTP
• 8 NADH (from acetate) -gt 24 ATP
• 2 FADH2 -gt 4 ATP
• Respiration, total 38 ATP per mole of glucose

17
Aerobic Respiration
18
Anaerobic Respiration
19
Chemolithotrophic respiration
20
Phototrophic metabolism