Biochemistry- Metabolism: Glycolysis, Krebs and ETC Flashcards
glycolysis starting and ending materials, products and reactants
Reactants: glucose, 2 ADP + 2 NAD+ + 2Pi-> 2 Pyruvate + 2 ATP + 2NADH + 2H+
which step of glycolysis is rate limiting ? what enzyme is used?
step that produces fructose-1,6 bisphosphate , uses PFK enzyme
How is PFK controlled by ATP/ADP levels?
activated by ADP, inhibited by ATP
Steps of glycolysis ( main products only)
glucose -> G-6P -> F-6P -> F-1,6BP -> 2-triose phosphate (3GP) -> 1,3-BPG -> 3-PG - > 2 PG -> PEP - Pyruvate
In which steps of glycolysis are byproducts formed
ATP-> ADP:
glucose-> G-6P :ATP->ADP
F-6P -> F-1,6BP: ATP->ADP
ADP-> ATP
1,3-BPG-> 3PG: ADP-> ATP
PEP-> Pyruvate: ADP->ATP
H2O
2-PG-> PEP : H2O out
NAD+ + Pi-> NADH + H-
2 triose phosphate (3GP)-> 1,3-BPG
what happens to pyruvate formed from glycolysis in aerobic conditions?
2 pyruvate ( per 1 glucose) -> acetyl coA + 2 CO2- > Krebs cycle
what happens to pyruvate in anaerobic conditions?
fermentation:
2 pyruvate + NADH -> 2lactic acid + NAD + via lactate dehydrogenase
forms 2 ATP and regenerates NAD+
where does glycolysis occur?
in the cytosol
Krebs cycle - where it occurs and how many turns of the cycle come from 1 molecule of glucose
occurs in the mitochondria, 2 turns of the cycle/ glucose
overall reaction of krebs - reactants and products
acetyl coA + 3 NAD+ + 1 FAD + ADP + Pi-> 2 CO2 + 1 coA + 3 NADH + 3 H+ + 1 FADH2 + 1 GTP ( turns to ATP via substrate level phosphorylation)
cycle = 2 turns , numbers above = per 1 turn
krebs cycle steps ( main products )
acetyl coA -> citrate -> isocitrate -> alpha-ketoglutarae -> succinyl coA-> succinate -> fumarate -> malate -> oxaloacetate , back to start of cycle
other products formed from krebs- where they occurred
CO2 produced from isocitrate -> a-keotglutarate and a-ketoglutarate-> succinyl coA
NADH + H+ produced in same steps as CO2 , with an added one produced when malate-> oxaloacetate
GTP produced when succinyl coA-> succinate
FADH2 produced when succinate-> fumarate
ETC 4 main complex names
iron-sulfur, cytochromes c, b , a and coenzyme Q
where does NADH enter the ETC
through NAD specific dehydrogenase flavoproteins
where do e- from FADH2 enter the ETC
directly at coenzyme Q
how many molecules of ATP do FADH2 vs NADH produce?
NADH= 3 molecules of ATP FADH2= 1 ATP
what kind of gradient exists in the IMM for the ETC?
electrochemical
what is the final e- acceptor at the end of the ETC?
oxygen , accepts e- from cytochrome A to produce H2O
what is the realistic net yield of ATP aerobic respiration ?
30-32 ATP per molecule of glucose
where does substrate level phosphorylation occur in krebs cycle?
in the krebs cycle, when GTP is made from GDP and Pi
when does oxidative phosphorylation occur?
at the end of the ETC , when ATP is produced by coupling the flow of e- from NADH and FADH2 to O2
what type of force drives the movement of H ions against their concentration gradients to create energy?
proton motive force
where are the H+ ions in the ETC pumped to drive the proton electrochemical gradient?
from mitochondrial membrane into the intermembrane space
which enzyme uses the electrochemical gradient to produce ATP?
ATP synthase
