EXAM 3 Lec 12

Question 1

mitochondrial structure

Answer 1

matrix, inner membrane, outer membrane, intermembrane space

Question 2

pyruvate dehydrogenase complex

Answer 2

coverts pyruvate to acetyl CoA
3 different enzymes
about 60 polypeptide chains 
larger than a ribosome 
located IN the mitochondrial matrix

Question 3

citric acid cycle or Krebs cycle

Answer 3

2/3 of total oxidation in most cells 
no oxygen required
begins with acetyl CoA conjugated to oxaloacetate to form citrate
loss of 2 CO2 molecules
4 reductions of NAD+ & FAD

Question 4

acetyl CoA from fatty acid catabolism

Answer 4

fatty acids are the second major source of acetyl CoA

Question 5

locations of acetyl CoA

Answer 5

in the mitochondrial matrix of animals

in the peroxisomes of plants

Question 6

advantages of the Krebs cycle

Answer 6

regulation of flux by the amount of intermediates available in the cycle to accept and metabolize acetyl-CoA
fusion of a small molecule to a larger molecule allows for more rearrangements of a 6-carbon molecule than a 2-carbon molecule, allowing for bonds to be arranged for efficient capture of energy

Question 7

what is fermentation

Answer 7

the biochemical response to environmental lack of oxygen

Question 8

characteristics of fermentation

Answer 8

under anaerobic conditions NADH cannot be reoxidized to NAD+ in the ETC, so NADH accumulates
NAD+ is limited and must be regenerated to continue glycolysis
regeneration of NAD+ by fermentation resupplies it for glycolysis

Question 9

naked mole rats

Answer 9

burrowing rodents
thermoconformers-functionally ectotherms
tunnels have poor air exchange, so they’re resistant to oxygen deprivation

Question 10

hypoxic (5% O2) atmosphere on mice vs. mole rat

Answer 10

mice survive for an average of 10 min

mole rat survives for over 300 min (+5 hours)

Question 11

anoxic (0% O2) atmosphere on mice vs. mole rat

Answer 11

mice survive an average of 45 sec

mole rat survives for 18 min

Question 12

how do naked mole rats survive anoxia

Answer 12

they avoid the regulated shutdown of glycolysis in the brain

Question 13

how does lack of oxygen affect the ETC

Answer 13

no ATP production and accumulation of NADH

causes the Krebs cycle to stop since there is no NAD+, causing citrate to accumulate

Question 14

how does the accumulation of citrate affect glycolysis

Answer 14

citrate is an allosteric inhibitor of the first phase in glycolysis
it blocks the formation of fructose, stopping glycolysis