anaerobic fermentation TCA cycle

Question 1

how much energy is harvested form the conversion of one glucose to two pyruvate molecules

Answer 1

2 ATP and 2NADH

Question 2

oxidative phosphorylation

Answer 2

-harvest ATP from the oxidation of NADH and FADH2 using O2
-occurs int he mitochondrial inner membranes
-electron transfer is coupled with the transfer of proton across the membrane generating the proton motive force
-ATP synthase produces ATP using proton motive force

Question 3

energy yield of NADH and FADH2

Answer 3

2.5 mols of ATP per NADH
1.5 mols of ATP per FADH2

Question 4

complete oxidation of glucose to CO2 and H2O by glycolysis, TCA cycle, and oxidative phosphorylation generates _____ATP

Answer 4

32

Question 5

anaerobic fermentation

Answer 5

-happens when not enough O2 is present so oxidative phosphorylation cannot occur
-to continue glycolysis NAD+ is regenerated from NADH by reducing pyruvate to lactate, that is released into blood circulation
-ATP is generated without O2, less efficient
-only way to generate ATP in blood cells bc they do not have mitochondria

Question 6

fate of lactate

Answer 6

-formation of lactate decreases the intracellular pH which inhibits glycolysis
-lactate and H+ are transported to the blood stream by lactate-H+ symporter
-lactate is converted to pyruvate again where O2 supply is sufficient

Question 7

overproduction or underutilization of lactate may decrease blood pH (lactic acidosis)

Answer 7

-tissue hypoxia due to circulatory and pulmonary failure
-vigorous exercise
-liver disease
-ethanol
-thiamin deficiency

Question 8

ethanol fermentation

Answer 8

-yeast convert pyruvate to ethanol when O2 is not sufficient
-with O2 is available later, ethanol is converted to acetate, which is used as an energy source
-human has used ethanol fermentation to make bread and alcoholic beverages

Question 9

pyruvate dehydrogenase complex

Answer 9

-located in the mitochondria
-catalyzes the conversion of pyruvate to acetyl CoA which is irreversible
-large complex formed by the association of 3 enzymes
-E1 pyruvate dehydrogenase
-E2 dihydrolipoyl transacetylase
-E3 dihydrolipoyl dehyrogenase

Question 10

Acetyl CoA

Answer 10

-produced from glucose, fatty acids, and some amino acids (ketogenic)
-fuel of tricarboxylic acid (TCA) cycle
-material for fatty acid synthesis and ketogenesis
-cannot be used to make glucose

Question 11

TCA is a source of biosynthetic intermediates

Answer 11

-intermediates in TCA cycle are critical building blocks for gluconeogenesis and amino acid synthesis (neurotransmitters)
-decrease in the concentration of the intermediated will slow down the utilization of acetyl CoA and energy production

Question 12

TCA cycle overview

Answer 12

location: mitochondria
input: acetyl CoA
output: 2 CO2
energy harvested: 3 NADH
1 FADH2
1GTP

Question 13

anaplerotic reactions

Answer 13

-anaplerotic (filling up) reactions supply TCA cycle intermediates
-when amino acids are not sufficient, pyruvate is the main source of TCA cycle intermediates

Question 14

what makes the intermediates

Answer 14

-aspartate - oxaloacetate
-amino acids- fumarate
-valine and isoleucine- propionyl CoA- succinyl CoA
-amino acids- glutamate- a-ketoglutarate
-amino acids- pyruvate- acetyl CoA and oxaloacetate

Question 15

pyruvate carboxylase

Answer 15

–catalzes the most important anaplerotic reaction
-critical for gluconeogenesis
-high in both liver and nervous tissues

Question 16

pyruvate carboxylase defiency

Answer 16

-severe lactic acidosis or death in infancy
-can be treated with triheptanoin which are converted to succinyl CoA

Question 17

glycolysis and TCA summary

Answer 17

location: cytosol and mitochondria
input: glucose
output: 6 CO2
energy harvested
2 ATP
2 GTP (ATP)
10 NADH
2 FADH2

Question 18

Which of the following metabolites is not part of the TCA cycle
oxaloacetate
a-ketoglutarate
citrate
lactate
succinate

Answer 18

lactate