ch 2 getting energy from energy

Question 1

krebs cycle

also known as the

Answer 1

citric acid cycle

Question 2

krebs cycle

this series of energy-producing chemical reactions begins in the

Answer 2

mitochondria after pyruvate arrives

Question 3

krebs cycle

before the krebs cycle can begin

Answer 3

• the pyruvate loses a carbon dioxide group to form acetyl coenzyme A (acetyl CoA)
• the acetyl CoA combines with a four-carbon molecule (oxaloacetic acid or OAA) to form a six-carbon citric acid molecule that then enters the krebs cycle
• the CoA is released intact to bind with another acetyl group reforming the acetyle CoA to be used with the next pyruvate

Question 4

krebs cycle

the krebs cycle goes through eight steps rearranging the atoms of citric acid to produce different intermediate molecules called

Answer 4

keto acids

Question 5

krebs cycle

after producing keto acids this generates

Answer 5

1 ATP (for each pyruvate) and four energy molecules (3 NADH and 1 FADH2) which power the electron transport chain

Question 6

krebs cycle

in the final step of the krebs cycle

Answer 6

OAA is regenerated to get to the next cycle going and the carbon dioxide produced during this cycle is released from the cell to be exhaled from the lungs

Question 7

electron transport chain

the electron transport chain which requires

Answer 7

• oxygen
• the final step of cellular respiration
• generates the bulk of the ATP

Question 8

electron transport chain

the chain itself is a series of

Answer 8

enzyme complexes aligned on the inner folds of the mitochondria

Question 9

electron transport chain

electrons from the energy molecules NADH and FADH2 are passed into the

Answer 9

chain and bounced from one protein to the next much like a game of hot potato

Question 10

electron transport chain

at the end of the chain a molecule of H2O is created and the energy from the bouncing electrons power

Answer 10

• oxidative phosphorylation–where an enzyme called ATP synthase reattaches a phosphate group to ADP creating ATP
• for every glucose molecule metabolized 34 molecules of ATP are generated by the electron transport chain

Question 11

one last thing the severe sorness and fatigue you feel in your muscles after strenous exercise is the result of lactic acid buildup during

Answer 11

anaerobic respiration

Question 12

but glycolysis does need a steady supply of

Answer 12

NADH+ which usually comes from the oxygen-dependent electron transport chain

Question 13

in the absence of NADH+ the body begins a process called

Answer 13

• lactic acid fermentation
• in which one molecule of pyruvate combines with one molecule of NADH to produce ATP, a molcule of NAD+,plus a molcule of the toxic byproduct lactic acid

Question 14

while useful for energy creation in musles when O2 has been used up it hardly seems worth it–anaerobic respiration provides only

Answer 14

2 ATP molecules per glucose compared to the 38 of aerobic respiration

Question 15

tack on the creation of lactic acid which causes

Answer 15

• muscle fatigue (inability of fibers to contract) as a byproduct
• why does this process exist? we need to exercise and some of the muscle fibers (not all) will inevitably run out of oxygen
• lucky for us the liver has a built in mechanism to rid the body of lactic acid though it is not as fast as we like