Glycolysis Flashcards
What is glycolysis?
a series of biochemical reactions by which glucose is converted to pyruvate (or lactate), releasing energy in the process
Glycolysis has 2 phases. Name them.
preparatory phase
payoff phase
What happens in the preparatory phase? (general overview)
glucose —- F-1,6-BP—– G-3-P
What happens in the payoff phase? (general overview)
G-3-P—pyruvate or lactate
What is the net gain of ATP in glycolysis and how does it balance to this?
net gain of 2ATP
4ATP produced in payoff phase, but 2ATP required in preparatory phase
How many steps are there overall in glycolysis?
10
What is the first step of glycolysis and what enzyme is involved? Importance?
conversion of glucose to glucose-6-phosphate by hexokinase
irreversible
What is the second step of glycolysis? Importance?
conversion of G-6-P to F-6-P
readily reversible
What is the 3rd step of glycolysis? Importance? Catalyst?
conversion of F-6-P to F-1,6BP
irreversible
catalysed by phosphofructokinase-1
What happens in step 4 of glycolysis? Importance?
cleavage of F-1,6BP to triose sugars
one is DHP and one is G-3-P
readily reversible
What happens in step 5 of glycolysis? Importance?
interconversion of trios sugars
DHP converted to G-3-P (glyceraldehyde - 3-phosphate)
readily reversible
What happens in step 6 of glycolysis? Catalyst? Importance?
conversion of G-3-P to 1,3-PG
catalysed by G-3-P dehydrogenase
2NADH produced!
What happens in step 7 of glycolysis? Catalyst? Importance?
1,3-PG converted to 3-PG
phosphoglycerate kinase
2ATP produced!!
What happens at step 8 of glycolysis? Importance?
3-PG converted to 2-PG
reversible
What happens in step 9 of glycolysis? Importance?
2-PG converted to PEP
reversible
What happens in step 10 of glycolysis? Catalyst? Importance?
PEP converted to pyruvate
catalyst pyruvate kinase
2ATP produced!!
What are the most important steps in glycolysis? State briefly why they are important.
Step 1 - glucose to G-6-P, irreversible Step 3 - F-6-P to F-1,6BP, irreversible Step 6 - G-3-P to 1,3PG, produces 2NADH Step 7 - 1,3PG to 3PG, 2ATP produced Step 10 - PEP to pyruvate, 2ATP produced
Why does NAD+ need to be regenerated?
for reduction of various intermediate metabolites
What happens to pyruvate at the end of glycolysis?
- converted to ethanol (fermentation in yeast)
- used in citric acid cycle (after being converted to acetyl CoA in aerobic conditions)
- converted to lactate in anaerobic conditions in exercising skeletal muscle
What is the Cori Cycle?
interaction between muscle and liver to compensate for the oxygen debt when muscles respire anaerobically (liver converts lactate to glucose)
