3 Metablic Pathways And ATP Production I Flashcards
Q: What are the 3 stages of cellular metabolism?
A: glycolysis, TCA cycle and oxidative phosphorylation
Q: Draw cartoon for 3 stages of cellular metabolism.
Diagram
Q: How does the combustion of glucose overcome its large activation energy?
A: having several enzyme catalysed reactions with smaller Ea
Q: What is overall glycolysis?
A: conversion of glucose to 2 pyruvate
Anaerobic
also produces 2ATP and 2NADH
Q: What is the net ATP gain/loss during glycolysis?
A: 2 gain (4 gain and 2 loss)
Q: First 5 steps of glycolysis.
A: glucose -> glucose-6-phosphate
E: hexokinase
ATP in and ADP out (1 ATP used)
Proton produced
glucose-6-phosphate -> fructose-6-phosphate
(((E: phosphoglucose isomerase)))
fructose 6 phosphate -> fructose-1,6-bisphosphate
E: phosphofructokinase
ATP in and ADP out (1 ATP used)
fructose-1,6-bisphosphate -> glyceraldehyde 3-phosphate + dihydroxyacetone phosphate
(((E: aldolase
(Opening up fructose ring))))
dihydroxyacetone phosphate -> glyceraldehyde 3-phosphate
(((E: triose phosphate isomerase)))
Q: What do kinases do?
A: transfer phosphate
Q: What is the result of the first 5 steps of glycolysis?
A: 2 ATP used and 2 glyceraldehyde-3-phosphates made
Q: What is the result of the second half of glycolysis?
A: 2 ATP used up and 4 made and 2 pyruvate made
Q: Define substrate level phosphorylation.
A: production of ATP as a result of the direct transfer of high energy phosphate group from intermediate substrate in biochemical pathway to ADP
Q: Define oxidative phosphorylation.
A: ATP production using energy derived from electron transfer in an electron transport system
Q: What are the 3 fates for pyruvate?
A: alcohol fermentation, lactate generation (anaerobic respiration), acetyl CoA generation
Q: What conducts alcohol fermentation of pyruvate and under what conditions and how?
A: yeast, anaerobic
Pyruvate -> acetaldehyde
E: pyruvate decarboxylase
H+ in and CO2 out
Acetaldehyde -> ethanol
E: alcohol dehydrogenase
NADH and H+ in and NAD+ out
Q: What conducts generation of lactate from pyruvate and under what conditions and how?
A: mammalian muscle, anaerobic (intense exercise)
Pyruvate -> lactate
E: lactate dehydrogenase
NADH and H+ in and NAD+ out
Q: How can lactate dehydrogenase be a diagnostic tool and for what? (6)
A: elevated levels in blood
Stroke Heart attack Liver disease Muscle injury Muscular dystrophy Pulmonary infarction
Q: What does lactate dehydrogenase do?
A: catalyse conversation of pyruvate to lactate
Q: What is creatine phosphate? Can be used to? Equation?
A: acts as a large phosphate reservoir
Can be used to phosphorylate ADP to ATP
creatine phosphate -> creatine + ATP
E: creatine kinase
ADP and H+ in and ATP out
Q: How can creatine phosphate be a diagnostic tool and for what? (4)
A: when muscle is damaged it can leak into blood
Elevated can be used to
Diagnose myocardial infarction
Determine extent of muscular disease
Evaluate cause of chest pain
Help discover carriers of muscular dystrophy
Q: Why does the body need NAD+?
A: dehydrogenation of glyceraldehyde 3-phosphate (first step to generating ATP in body)
Q: What conducts generation of a acetyl CoA from pyruvate and how?
A: mitochondria
Pyruvate + HS-CoA -> acetyl CoA +CO2
E: pyruvate dehydrogenase complex
NAD+ in and NADH out
Q: What makes the pyruvate dehydrogenase complex?
A: 3 enzymes and 5 co factors
Q: What are the 5 co factors involved in the pyruvate dehydrogenase complex?
A: lipoamide Thiamine pyrophosphate FAD CoA NAD+
Q: Name 3 enzymes and their prosthetic groups in the pyruvate dehydrogenase complex.
A: lipoamide reductase-transacetylase and lipoamide
Dihydrolipoyl dehydrogenase and FAD
Pyruvate decarboxylase and thiamine pyrophosphate TPP
Q: What does FAD stand for?
A: flavine adenine dinucleotide
Q: How does thiamine pyrophosphate act in pyruvate dehydrogenase complex and What is it a derivative of?
A: readily loses proton to produce carbanion that attacks pyruvate, vitamin B
Q: How does lipoamide act in pyruvate dehydrogenase complex?
A: undergoes oxidation and reduction
Has long arm that allows dithiol group to swing from one active site to another
Q: How does FAD act in pyruvate dehydrogenase complex?
A: accepts and donates 2 electrons and 2 protons
FAD + 2 e- + 2H+ FADH2
Q: Last 5 steps of glycolysis.
A: all x2
Glyceraldehyde-3-phosphate -> 1,3-bisphosphoglycerate
E: Glyceraldehyde-3-phosphate dehydrogenase
(((NAD+ in and NADH out
Pi in)))
1,3-bisphosphoglycerate -> 3-phosphoglycerate
E: phosphoglycerate kinase
ADP in and ATP out
(substrate level phosphorylation)
3-phosphoglycerate -> 2-phosphoglycerate
(((E: phosphoglycerate mutase
(Shuffling of phosphate group from 3 to 2 position))))
2-phosphoglycerate -> phosphoenolpyruvate
(((E: enolase
(Dehydration reaction))))
Phosphoenolpyruvate -> pyruvate
E: pyruvate kinase
ADP in and ATP out
(substrate level phosphorylation)
Q: What are the 5 steps of the pyruvate dehydrogenase complex?
A: 1. Pyruvate — decarboxylated —> hydroxyethyl TPP
- Oxidation and transfer to lipoamide to give acetyloamide
- Transfer or acetyl group to CoA -> acetyl CoA
- Regeneration of oxidised lipoamide
- Regeneration of oxidised FAD, generating NADH
Q: Where does acetyl CoA go?
A: into Krebs cycle and ultimately produces ATP by oxidative phosphorylation in the electron transport chain
Q: What is the net ATP gain through anaerobic respiration vs aerobic?
A: an = 2
Aer = 38
Q: Describe ligation requiring ATP cleavage.
Formation of covalent bonds eg carbon-carbon
Q: Describe isomerisation.
A: rearrangement of atoms to form isomers
