Energy Production From Carbohydrates Flashcards
What are the major functions of the pentose phosphate pathway?
Produce NADPH in cytoplasm, reducing power for anabolic processes, maintains free -SH in RBC on cysteine, produce C5 ribose
Write a reaction for phase I of pentose phosphate pathway
G6P + 2NADP —> C5 sugar phosphate + 2NADPH + 2H+ + 2CO2
Write a reaction for phase II of pentose phosphate pathway
3C5 sugar phosphate —> 2 fructose-6-phosphate + glyceraldehyde-3-phosphate
What happens in G6PDH deficiency?
Disulphide bridge formation in RBC due to low levels of NADPH. Insoluble aggregates called heinz bodies form - premature destruction of RBC
Draw out the glycolysis pathway

Give the equations for the 3 committing steps in glycolysis
Glucose —> G6P
F6P —> F-1,6-P
PEP —> pyruvate
What does pyruvate dehydrogenase catalyse?
This reaction is irrversible

What control mechanisms is PDH subject?
Acetyl CoA allosterically inhibits PDH, ADP promotes, ATP/NADH inhibit, activated when there is a lot of glucose
What are the functions of glycolysis?
Oxidises glucose, 2 NADH produced, net synthesis of 2 ATP, produces C6 and C3 intermediates (glycerol phosphate, 2,3-BPG)
What ismoers are carbohydrates usually found in the body?
D isomers
List the main features of glycolysis
Oxidative, exergonic, C6–>2 C3, no loss of CO2, ATP generated, useful intermediates, substrate level phosphorylation
Write an equation for dihydroxyacetone phosphate going to glycerol phosphate

What stimulates pyruvate kinase?
High insulin:glucagon ratio
What inhibits phosphofructokinase?
High levels of ATP cause allosteric inhibition
Where would you find glucokinase and hexokinase?
Hexokinase - liver and muscle
Glucokinase - liver only
What stimulates hexokinase and glucokinase?
An increase in glucose (or a decrease in G6P)
Why is lactate dehydrogenase needed?
RBC cannot regenerate NAD+ any other way
Write the reaction that occurs in RBC to produce pyruvate

Write the overall equation for glycolysis
Glucose + 2Pi + 2ADP + 2NAD+ —> 2 pyruvate + 2H2O + 2H+ + 2NADH + 2ATP
Draw out the TCA cycle

Where does the TCA cycle occur?
Mitochondiral matrix
What does the TCA pathway require?
NAD+, FAD and oxaloacetate
What is the main function of the TCA cycle?
Break the C-C bond in acetate and oxidise the atoms to CO2. Doesn’t function anaerobically
Approximately how many molecules of ATP are produced per molecule of glucose in the TCA cycle?
36 molecules of ATP per molecule of glucose
