Review of Basics

Question 1

define human metabolism

Answer 1

OXIDATION of carbs, lipids, and proteins to create energy

Question 2

what is the most basic step of human metabolism?

Answer 2

glycolysis-breakdown of glucose to form energy in a cell

Question 3

what are the 3 enzymes that regulate glycolysis?

Answer 3

1. hexokinase (1)
2. phosphofructokinase-1 (3)
3. pyruvate kinase (10)

Question 4

how many ATP moles are used/gained in glycolysis?`

Answer 4

2 needed, 4 made, 2 net gained

Question 5

what is the cori cycle and where does it occur?

Answer 5

way to make ATP, recycle NADH–> NAD+ and produce pyruvate in ANAEROBIC conditions; occurs in the muscles and RBCs

Question 6

when pyruvate is made in the Cori cycle, where does it go?

Answer 6

quickly converted to lactic acid–> liver–> oxidized back into pyruvate–> gluconeogenesis to ship glucose back to muscles

Question 7

why is the cori cycle unsustainable?

Answer 7

glycolysis produces 2 ATP, but gluconeogenesis consumes 6–> net loss of 4 atp/cycle

Question 8

t/f: gluconeogenesis only occurs in the liver

Answer 8

false! can occur in the kidneys and a tiny amt in SI if under starvation conditions

Question 9

t/f: most gluconeogeneis steps are the reverse of glycolysis

Answer 9

true! but some “bypass” rxns occur to reverse

Question 10

what are some conditions under which gluconeogenesis would occur?

Answer 10

starvation, prolonged exercise, high protein/ketogenic diet, STRESS!

Question 11

what are 4 substrates for gluconeogenesis?

Answer 11

1. pyruvate from glycolysis
2. lactate from Cori Cycle
3. alanine (AA)
4. glycerol from breakdown of TAGs

Question 12

what enzyme oxidizes pyruvate so it can enter the Kreb’s cycle? where does this enzyme reside? what is produced?

Answer 12

pyruvate dehydrogenasein the mitochondrial matrix!

produces: acetyl CoA + CO2

Question 13

how many steps are in the Kreb’s cycle?

Answer 13

8

Question 14

in one turn of the Kreb’s cycle, how many and which electron carriers are formed? how many of these per glucose molecule?

Answer 14

3 NADH
1 FADH2
1 GTP

double these for one glucose molecule b/c each glucose causes 2 turns of the CAC

Question 15

each NADH generates _______ ATP

Answer 15

2.5

Question 16

each FADH2 produces _______ ATP

Answer 16

1.5

Question 17

what is GTP equivalent to?

Answer 17

one ATP (energetically)… can be used directly for energy requiring rxns

Question 18

where does the ETC occur?

Answer 18

inner mitochondrial membrane

Question 19

in addition to the ATP produced from the Kreb’s cycle’s formation of electron carriers, where else do we get ATP from in the process of metabolism (what should you not forget to factor into calculations?)

Answer 19

glycolysis (2 ATP + 2 NADH)

pyruvate oxidation (2 NADH)

Question 20

what is the process called by which ATP is created from passing electrons along the ETC?

Answer 20

oxidative phosphorylation