Unit 2--Lecture 8 (Fermentation and Respiration) Flashcards
Regenerating NAD+
Glycolysis = 2 NADH
Entner-Doudoroff = 1 NADH & 1 NADPH
TCA = 4 NADH & 1 FADH2
Pentose Phosphate also regenerates reduced NAD(P)H molecules
Two main ways to regenerate NAD+
Organic: fermentation
Inorganic: Respiration
Fermentation
Organic
Performed by anaerobic microorganisms
Primary purpose: regenerate NAD
Secondary purpose: generate additional energy
Mixed Acid Fermentation
E. coli
Metabolic flexibility
Dumping electrons vs ATP generation
Produces acetate and ethanol
Some bacteria can do TCA backwards (gets rid of electron)
Redox Potential Energy
Best donors (least electronegative) at top
Best acceptors (most electronegative F/O) at bottom
Electron Transport Systems
Occurs on membranes
Inner membrane of bacteria/archaea (cytoplasmic membrane)
Inner membrane of mitochondria/chloroplasts
The Respiratory ETS
Electrons from NADH –> O2 release energy
—-requires intermediates
—-multiple steps
NADH Oxidase
Quinones
Cytochromes
Flavoproteins
Cofactor
FAD or FMN
Carry 2 protons, 2 electrons
Quinones
Isoprenoid lipids
UQ, MQ, PQ
Carry protons and electrons
Iron Sulfur Proteins
Electron carrier only
Cytochromes
Iron + heme
Electron carriers only
Mitochondrial Respiratory ETS
4 Complexes
I: e- from NADH to Coenzyme Q
II: e- from FADH2 to Coenzyme Q
III: Coenzyme Q to Cytochrome C
IV: Cytochrome C to O2 (aa3)
Driving protons out of cytoplasm
NADH = 10 H+ out
FADH2 = 6 H+ out
E. coli Respiratory ETS
NDH-1 pumps 4 protons and 2 electrons
NDH-2 pumps 0
Cytochrome bo pumps 1 proton and 1 electron
Cytochrome bd pumps 0
NDH-1 —> Q —> Cytochrome bo
Proton Motive Force (PMF)
PMF used directly for cell activities:
Creates ATP
—-ATP synthase at cell membrane
Drives flagellar rotation
—-motors at base of flagella
Pushes ions into, out of cell
—-Symport: same direction as proton movement
—-Antiport: opposite direction
Proton Potential Creates ATP
F1 F0 ATP synthase makes ATP
Protons enter the F0 subunit and cause it to rotate
F0 rotation drives the
F1 subunit shaft
Synthesizes ATP from ADP + Pi