3. Metabolic pathways and ATP production I Flashcards
How is the high activation energy in combustion of glucose overcome?
By having multiple enzyme-catalysed reactions with lower AEs
Where does glycolysis occur?
Cytoplasm
What type of reaction is glycolysis?
Anaerobic
What are the 2 main concepts I glycolysis?
Formation of high energy compound (invest ATP)
Splitting of high energy compound (produce ATP)
What are the products of glycolysis?
2 X Pyruvate (C)
2 X ATP
2 X NADH
How many ATP are generated from glycolysis?
4 ATP generated
But 2 ATP used
Net gain = 2 ATP
What do all kinases in glycolysis catalyse?
Transfer of a phosphate group from a donor onto a substrate
Which steps of glycolysis use and produce ATP?
- Glucose -> Glucose-6-Phosphate (-ATP)
- Fructose-6-phosphate -> Fructose-1,6-bisphosphate (-ATP)
- 1,3-bisphosphoglycerate -> 3-phosphoglycerate (+ 2 ATP)
- Phosphoenolpyruvate ->Pyruvate (+ 2 ATP)
How many separate reactions are involved in glycolysis?
10
What is substrate level phosphorylation and when does this occur in glycolysis?
Formation of ATP by direct transfer of high-energy phosphate intermediate to ADP
Occurs in step 7 and 10 of glycolysis
How can NAD+ levels be replenished anaerobically?
Pyruvate fermented to ethanol (Yeasts)
Pyruvate used to generate lactate (mammals)
What is required for Pyruvate to be fermented to ethanol?
Pyruvate decarboxylase
Alcohol dehydrogenase
What is required for Pyruvate to be used to generate lactate?
Lactate dehydrogenase (LDH)
Where is LDH found?
In cells of heart, muscles, brain, liver, kidney, lungs
What can increased levels of LDH indicate?
Stroke
Heart attack
Hepatitis
Injury
What buffers the demand for phosphate in muscles?
Creatine phosphate
What is produced when creatine kinase acts on creatine phosphate?
Creatine
ATP
How can creatine kinase be used diagnostically?
Creatine kinase leaks into blood when muscle is damaged
Can identify heart attack or extent of muscular disease
Where does generation of Acetyl CoA occur?
Mitochondria
What type of reaction is the generation of Acetyl CoA?
Aerobic
What are the 3 fates of pyruvate?
Alcoholic fermentation
Generation of lactate
Generation of Acetyl-CoA
Equation for generation of Acetyl CoA
Pyruvate + CoA -> Acetyl CoA + CO2
What is required for generation of Acetyl CoA?
Pyruvate dehydrogenase complex
What does the Pyruvate dehydrogenase complex consist of?
3 Enzymes
5 Co-factors
What are the 3 enzymes in the Pyruvate dehydrogenase complex?
Lipoamide Reductase Transacetylase
Dihydrolipoyl Dehydrogenase
Pyruvate Decarboxylase
What are the 5 co-factors in the Pyruvate dehydrogenase complex?
Thiamine pyrophosphate Lipoamide FAD CoA NAD+
Which of the co-factors in the Pyruvate dehydrogenase complex are prosthetic groups (permanent)?
Thiamine pyrophosphate
Lipoamide
FAD
What do the 3 enzymes of the Pyruvate dehydrogenase complex work together to do?
Generate an acetyl group and transfer it to CoA so Acetyl CoA can enter the TCA cycle
Regenerate active PDH complex for another series of reaction
Where does acetyl CoA go once produced and what does it do?
Enters TCA cycle,
Forms ATP by oxidative phosphorylation
