Week 5 - CHO metabolism Flashcards
What is the relevance of carbohydrate metabolism?
Instantaneous source of energy with/without oxygen.
Protein sparing - maintains muscle mass
Can be converted to fat for stored energy
Stored in the muscle and liver as glycogen - glycogen content 5x higher in the liber than the muscle.
Issues with too much sugar
Chronic inflammation, build-up of fat, affected by glycaemic control.
When working at VO2max how much energy comes from carbs?
Around 70% - when working at >85% VO2max.
What is glucose converted into in glycolysis? Why?
Glucose-6-phosphate, to lock in into the cell and stop it diffusing out.
Glucose-6-phosphate can be stored as glycogen or converted from glycogen back to GP6 when needed in extreme exercise or starvation.
What is glucose-6-phosphate converted to?
Pyruvic acid which becomes lactic acid (anaerobic) or acetyl CoA (aerobic).
What happens to acetyl CoA?
Enters the Krebs cycle to produce H+ ions, electrons and electron carriers which enter the electron transport chain in the mictochondria to covert ADP to ATP.
What is the role of electron carriers?
Convert ADP to ATP.
What is glycolysis?
Breakdown of glucose to two molecules of pyruvate
What is the link reaction?
Breakdown of pyruvate to acetyl CoA.
Give the three steps of glycolysis
Glucose is broken down into fructose diphosphate
This forms 2 molecules of glyceraldehyde-3-phosphate
These form 2 molecules of pyruvate.
What does glycolysis produce per glucose molecule?
2x ATP
2 NADH (electron carriers)
Is glycolysis aerobic or anaerobic?
Anaerobic - but the first step in an aerobic process.
Outline the link reaction
Connects glycolysis + Krebs cycle.
Pyruvate is oxidised to acetyl CoA by removal of hydrogen and CO2. Coenzyme A is added.
What is the Krebs cycle?
Breakdown of acetyl CoA to CO2.
Outline the Krebs Cycle
What does it produce?
Acetyl and oxaloacetate combine to form citrate.
Each cycle produces 1 ATP, 3 NADH and 1 FADH2, 3 CO2.
Doubled per molecule of glucose.