lecture 5

Question 1

catabolic pathways

Answer 1

-aerobic respiration (oxygen)
- fermentation (no oxygen)
- anaerobic respiration (other than oxygen)

Question 2

fermentation

Answer 2

• process induced by microorganisms/enzymes splitting complex organic cmpds in simple substances
• anaerobic conditions
• glycolysis can produce ATP without oxygen
• absense of oxygen, glycolysis couples with fermentation to produce ATP
• regeneration of NAD+
• final electron acceptor is pyruvate/derivatives
• cell relies exclusively on glycolysis (produce ATP)
• OP, less effecient, still ATP produced without oxygen
• 2 types: alcohol fermentation; lactic acid fermentation

Question 3

energy payoff stage

Answer 3

• dehydrogenase enzyme
  – oxidises GAP –> NADH
  – attaches P group
• Pi = PO42-

Question 4

regeneration of NAD+

Answer 4

• aerobic conditions NAD+ regenerated when NADH transfers electrons to ETC
• anaerobic conditions NAD+ regenerated by transferring electrons from NADH to pyruvate

Question 5

alcohol fermentation

Answer 5

• pyruvate decarboxylase

Question 6

lactic acid fermentation

Answer 6

• lactate dehydrogenase

Question 7

comparison (aerobic vs. fermentation

Answer 7

• produce ATP from sugar
  – glycolysis, net of 2 ATP by SLP
• differ oxdising agents for NADH
  – NADH passed to organic molecule to regenerate NAD+ (fermentation)
  – electrons of NADH passed to O2 via ETC to regenerate NAD+ (respiration)
• more ATP from aerobic respiration
  – no oxygen energy stored in pyruvate unavailable
  – glucose yield 32 ATP, with fermentationsame glucose yields 2 ATP

Question 8

fermentation process

Answer 8

• yeast/many bacteria are facultative anaerobes (survive fermentation/respiration)
• prokaryotes may have generated ATP exclusively from glycolysis (oldest bacterial fossils before oxygen accumulated)
• glycolysis is ubiquitous metabolic pathways
  – occuring in cytosol without membrane-enclosed organelles (suggests glycolysis evolved early in history)

Question 9

aerobic, fermentation, anaerobic compared

Answer 9

• growth conditions
  – aerobic
  – anaerobic
  – anaerobic
• ETC
  – yes
  – no
  – yes
• final electron acceptor
  – oxygen
  – organic molecule (pyruvate/acetaldehyde)
  – inorganic substance (NO3-/SO42-
• types of phosphorylation
  – mostly oxidative, some substrate-level
  – substrate level
  – mostly oxidative, some substrate-level

Question 10

anabolic pathways

Answer 10

• proteins
  – amino acids
  –> pyruvate
  –>acetyl CoA
  –> citric acid cycle
• carbohydrates
  – sugars
  –> glycolysis (glucose > G3P > pyruvate)
• fats
  – glycerol
  –> G3P
  – fatty acids
  –> acetyl CoA

Question 11

glycolysis

Answer 11

• glyceraldehyde phosphate
• phosphoenol-pyruvate (PEP)
• pyruvate

Question 12

citric acid cycle

Answer 12

• acetyl CoA
• citrate
• A-keto-glutatrate
• malate
• oxaloacetate

Question 13

catabolism of foods

Answer 13

• proteins
  – digested
  – deamination
• fats
  – digested
  – fatty acids
  – beta oxidation