Carbohydrates 3 Flashcards
How many molecules of G-3-P enter the payoff phase?
2
How many ATP are used in the prepatory phase?
2
How many ATP are made during the payoff phase?
4
What is the first reaction of glycolysis?
Phosphorylation of glucose
How many ATP is used during the first stage of glycolysis? (phosphorylation of glucose) And what enzyme is used?
1 ATP
Hexokinase
What is the second stage of glycolysis? And what is the enzyme?
Conversion of G - 6 - P to F-6-P
Phosphohexose Isomerase
Why does the second step of glycolysis proceed in both directions?
Reaction has a low free energy
What is the stage of glycolysis apart from step 1 (phosphorylation of glucose) that requires ATP?
Phosphorylation of F-6-P to F-1,6 - bisP (stage 3)
What is the catalyst for phosphorylation of F-6-P?
Phosphofructokinase -1
What is the splitting part of Glycolysis?
Step 4 - which is the cleavage F-1, 6-bisP, forms two different triose sugars
Catalyst is aldolase
What is stage 5 of glycolysis?
Interconversion of triose sugars
Enzyme used it triose phosphate isomerase
Dihydroxyacetone phosphate is converted to glyceraldehyde -3-phosphate
Forming 2 molecules of G-3-P
G-3-P is the only molecule that can enter the payoff phase
Which stage in glycolysis produces 2 molecules of NADH?
Stage 6, the oxidation of G-3-P to 1,3-bisPG
The catalyst is glyceraldehyde - 3 - phosphate dehydrogenase
The first payoff reaction in glycolysis
Reaction 6 (the oxidation of G-3-P to 1,3-bisPG) is coupled to which other reaction and why?
6 is coupled to 7 because 6 requires a lot of energy whilst 7 gives off a a lot of energy.
Describe reaction 7 and what is the substrate?
P transfer from 1,3-bisPhosphoglycerate to ADP, 2 ATP produced, phosphoglycerate kinase enzyme used
Spontaneous since highly exergonic
What is stage 8?
Conversion of 3, phosphoglycerate to 2, phosphoglycerate
Enzyme is phosphoglycerate mutase
What step of glycolysis is enolase used in?
Dehydration 2-PG to PEP (phosphoenolpyruvate)
Where does the ADP in the last stage of glycolysis get the phosphate?
PEP
Describe the last stage of glycolysis
Transfer of P from PEP to ADP
2 ATP produced, highly exergonic,
Pyruvate produced
Enzyme is pyruvate kinase
Where does NAD+ come from in the cell?
Niacin an essential vitamin
What is the difference between substrate level phosphorylation and respiration linked phosphorylation ?
Substrate level - requires soluble enzymes and chemical intermediates
Respiration linked means membrane bound enzymes and gradients of protons
What compound is used to replenish NAD+?
The different fates of pyruvate
What is NAD+ used for?
The reduction of various intermediate metabolites
What are the three fates of pyruvate?
Citric acid cycle, producing water and carbon dioxide
Fermentation to lactate
Fermentation to CO2 and Ethanol
How is pyruvate converted into ethanol?
Pyruvate + pyruvate carboxylase = Acetaldehyde
Acetaldehyde + Alcohol dehydrogenase + NADH = Ethanol + NAD+
