BIOL 201 Lecture Notes - Lecture 4: Blue Budgerigar Mutation, Competitive Inhibition, Insulin
Glycolysis: occurs in the cytoplasm, breaks down glucose into pyruvate
1.
Conversion of pyruvate to Acetyl-CoA via oxidation reaction
2.
Citric acid cycle: occurs in the matrix, produces NADH and FADH2electron carriers
3.
Electron transport chain: occurs in cristae of mitochondrial membrane, produces
bulk of ATP using proton motive force
4.
Metabolism take place in 4 stages
Analogous to burning wood to produce H2O and CO2, the key difference is that
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the amount of energy released in any given step closely matched to the amount of energy that
can be stored in intermediates (ATP, etc. )
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This prevents excessive waste by loss of energy as heat
○
cells break the overall reaction down into many intermediate steps
Different fuels (sugars and fatty acids) are reduced to common intermediates that can then share
subsequent pathways for combustion and ATP synthesis
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occurs in the cytosol in both eukaryotes and prokaryotes
•
it does not require molecular oxygen (O2) and is thus an anaerobic process
•
Catabolism: biological breakdown of complex substance into simpler constituents
•
Stage 1: Glycolysis
Steps
Add phosphate to glucose (use 1 ATP) to make
glucose-6-phosphate
1.
convert glucose to fructose to make C chain symmetrical
(ISOMERASE) producing fructose-6-phosphate
2.
add phosphate to fructose-6-phosphate to create
fructose-1,6-bisphosphate
3.
HULK SMASH
split into glyceraldehyde-3-phosphate and DHAP
4.
DHAP almost instantly converted into glyceraldehyde-3-
phosphate
5.
Add inorganic phosphate group to carbon 1 to create
1,3-biphosphoglycerate. Coupled reaction, lose
hydrogen to NADH. Aldehyde become 1,3
bisphosphoglycerate
6.
First phosphate removed, added to ADP to produce ATP
(converted to 3-phosphoglycerate)
7.
phosphate moves from carbon 3 to carbon 2 to align
with active site of enzyme (molecule becomes 2-
phosphoglycerate)
8.
Loss of water, converted to PEP (phosphoenolpyruvate)
9.
formation of 1 more ATP by loss of phosphate group,
converted to pyruvate.
10.
Drives them closer to activation energy of next forward reaction
▪
Not the same as catalysis: raises free energy of reactants by making them into higher
energy reactant
○
Removes glucose from the cytoplasm, increasing uptake of glucose by the cell
○
Glucose-6-phosphate can be made into glycogen, used by other enzymes in diverse
pathways
○
Fructose 6-phosphate also useful metabolite, useful in making glycolipids
○
The first step is "pump priming" and produces a useful metobolite
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Very large relative to glucose
○
The glucose "disassembly line" is performed by large machines
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If one machine breaks down or lack of particular part, slow down other steps
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Match supply to demand
○
Assembly lines are continuously monitored, and we can change the flux through them
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Cancer cells show increased glycolytic flux
○
Mutations in glycolytic enzymes found in tumors that make them resistant to regulation
○
Cancer cells rely heavily on glycolysis instead of aerobic respiration
○
Warburg hypothesized that cancer CAUSED by glycolysis; but it is known today to be a consequence instead
○
PET scan detects increase in glycolytic flux using radioactive glucose
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Glycolysis produces intermediate metabolites useful in rapid cell division and tumor growth
○
Rapidly growing tumors must thrive in low oxygen environments due to lack of blood vessel permeation
○
Glycolysis and cancer
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Steps with big -ΔG are effectively irreversible
Where do we want to control glycolysis?
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Regulation of Glycolysis
Lecture 4: Glycolysis
January 17, 2018
9:24 AM
Section 1 Page 1
Document Summary
Glycolysis: occurs in the cytoplasm, breaks down glucose into pyruvate. Conversion of pyruvate to acetyl-coa via oxidation reaction. Citric acid cycle: occurs in the matrix, produces nadh and fadh2 electron carriers. Electron transport chain: occurs in cristae of mitochondrial membrane, produces bulk of atp using proton motive force. This prevents excessive waste by loss of energy as heat. Different fuels (sugars and fatty acids) are reduced to common intermediates that can then share subsequent pathways for combustion and atp synthesis. Stage 1: glycolysis occurs in the cytosol in both eukaryotes and prokaryotes it does not require molecular oxygen (o2) and is thus an anaerobic process. Catabolism: biological breakdown of complex substance into simpler constituents. Add phosphate to glucose (use 1 atp) to make glucose-6-phosphate convert glucose to fructose to make c chain symmetrical (isomerase) producing fructose-6-phosphate add phosphate to fructose-6-phosphate to create fructose-1,6-bisphosphate. Add inorganic phosphate group to carbon 1 to create.
