Carbohydrates 3 Flashcards
What is glycolysis?
Biochemical reaction, not involving oxygen, that splits carbohydrates into pyruvic or lactic acid whilst producing ATP
What kind of phosphorylation does glyclysis produce ATP through?
Substrate level phosphorylation
What is the only way that energy can be made when O2 is not present?
Substrate level phosphorylation
Why is glycolysis often the process used to generate energy initially during exercise?
O2 cannot get to the cells quick enough
What are the 2 phases of glycolysis?
Preparation phase
Payoff phase
What happens during the preparative phase of glycolysis?
Two molecules of glucose-3-phosphate are produced per molecule of glucose
What happens during the payoff phase of glycolysis?
ATP is produced
What is the net gain of ATP in glycolysis and how is this distributed between the preparative and payoff phases?
2 ATP is used during the preparative phase and 4 ATP is gained during the payoff phase
Net gain of 2 ATP per molecule of glucose
How many steps are there in glycolysis?
10
How many of the 10 glycolysis steps are irreversible?
3
Why are the irreversible steps of glycolysis irreversible?
Delta G during those reactions is to highly negative, too much energy put be required to reverse the reaction
What are the 10 steps of glycolysis?
- Phosphorylation of glucose (glucose → glucose-6-phosphate)
- Conversion of G-6-P to F-6-P
- Phosphorylation of F-6-P to F-1,6-bisP
- Cleavege to F-1,6-bisP
- Interconversion of triose sugars
- Oxidation of glyceraldehyde-3-phosphate (G-3-P) to 1,3-bisphosphoglycerate (1,3-bisPG)
- P transfer from 1,3-bisPG to ADP
- Conversion of 3-PG to 2-PG
- Dehydrogenase of 2-PG to phosphoenolpyruvate (PEP)
- Transfer of P from PEP to ADP, producing pyruvate
What is fructose-1,6-bisP broken down to into step 4 of glycolysis?
Glyceraldehyde-3-P or dihydroxyacetone-P
What are the 3 irreversible steps of glycolysis?
Step 1 - Phosphorylation of glucose (glucose → glucose-6-phosphate)
Step 3 - Phosphorylation of F-6-P to F-1,6-bisP
Step 10 - Transfer of P from PEP to ADP, producing pyruvate
Why is glucose converted to fructose in step 3?
This lowers the activation energy to proceed due to the negative charges of fructose repelling each other