Post-absorption processing of carbohydrates Flashcards
Why is fructose suitable for use in diabetic jam?
Its metabolism is not controlled by insulin.
What are the possible fates of glucose?
- > acetyl CoA->ATP.
- > glycogen.
- > ribose phosphate->DNA/RNA.
- > fatty acids->lipids
- > glycoproteins/glycolipids
What is a healthy blood glucose concentration?
5mM
What happens at plasma glucose >8mM
Long-term vascular damage through protein glycation.
Which compound is the start point in the Krebs cycle and from what is it derived?
Acetyl CoA - derived from pyruvate, derived from glucose
What electron donor does the Kreb’s cycle produce for the electron transport chain?
NADH
How does the electron transport chain use electrons?
Uses the energy from them to create a proton gradient across the membrane.
What function does the proton gradient from the electron transport chain serve?
Used for ATP synthesis.
What are the two phases of anaerobic glycolysis?
Preparative phase - glucose -> fructose-1,6-bisphosphate, requires 2ATP.
Generating phase - fructose-1,6-bisphosphate to 2pyruvate - generates 4ATP and NADH (later converted to ATP in aerobic conditions).
How many molecules of ATP can be produced from NADH using oxidative phosphorylation?
3-5
In total how many molecules of ATP are produced by aerobic glycolysis?
5-7
How many molecules of ATP are produced from the complete oxidation of glucose via the Krebs cycle?
30-32
What are the key control reactions in glycolysis?
Glucose->Glucose-6-phophate (prevents glucose from leaving cell).
Fructose-6-phosphate->fructose-1,6-bisphosphate (via phophofructokinase)
Phosphoenolpyruvate->pyruvate (via pyruvate kinase)
How does glycolysis work in the absence of oxygen?
Pyruvate is converted to lactate. NAD+ is regenerated. 2 molecules of ATP are generated per molecule of glucose.
What is the control enzyme for glycogen synthesis?
Glycogen synthase.
