Review of Basics Flashcards
define human metabolism
OXIDATION of carbs, lipids, and proteins to create energy
what is the most basic step of human metabolism?
glycolysis-breakdown of glucose to form energy in a cell
what are the 3 enzymes that regulate glycolysis?
- hexokinase (1)
- phosphofructokinase-1 (3)
- pyruvate kinase (10)
how many ATP moles are used/gained in glycolysis?`
2 needed, 4 made, 2 net gained
what is the cori cycle and where does it occur?
way to make ATP, recycle NADH–> NAD+ and produce pyruvate in ANAEROBIC conditions; occurs in the muscles and RBCs
when pyruvate is made in the Cori cycle, where does it go?
quickly converted to lactic acid–> liver–> oxidized back into pyruvate–> gluconeogenesis to ship glucose back to muscles
why is the cori cycle unsustainable?
glycolysis produces 2 ATP, but gluconeogenesis consumes 6–> net loss of 4 atp/cycle
t/f: gluconeogenesis only occurs in the liver
false! can occur in the kidneys and a tiny amt in SI if under starvation conditions
t/f: most gluconeogeneis steps are the reverse of glycolysis
true! but some “bypass” rxns occur to reverse
what are some conditions under which gluconeogenesis would occur?
starvation, prolonged exercise, high protein/ketogenic diet, STRESS!
what are 4 substrates for gluconeogenesis?
- pyruvate from glycolysis
- lactate from Cori Cycle
- alanine (AA)
- glycerol from breakdown of TAGs
what enzyme oxidizes pyruvate so it can enter the Kreb’s cycle? where does this enzyme reside? what is produced?
pyruvate dehydrogenasein the mitochondrial matrix!
produces: acetyl CoA + CO2
how many steps are in the Kreb’s cycle?
8
in one turn of the Kreb’s cycle, how many and which electron carriers are formed? how many of these per glucose molecule?
3 NADH
1 FADH2
1 GTP
double these for one glucose molecule b/c each glucose causes 2 turns of the CAC
each NADH generates _______ ATP
2.5
each FADH2 produces _______ ATP
1.5
what is GTP equivalent to?
one ATP (energetically)… can be used directly for energy requiring rxns
where does the ETC occur?
inner mitochondrial membrane
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?)
glycolysis (2 ATP + 2 NADH)
pyruvate oxidation (2 NADH)
what is the process called by which ATP is created from passing electrons along the ETC?
oxidative phosphorylation
