4) Energy Production: Carbs 2

Question 1

How is Glycolysis regulated?

Answer 1

Allosteric regulation:
inhibited by high ATP
inhibited by high Citrate
Stimulated by high AMP
Stimulated by high F2,6BP

Hormonal Regulation (liver)
stimulated by insulin
Inhibited by glucagon

Question 2

regulation of hexokinase and pyruvate kinase

Answer 2

hormonal activation of pyruvate kinase by insulin
hexokinase product inhibited by G6P

Question 3

Regeneration of NAD+ anaerobically

Answer 3

2 moles NADH produced per glucose, therefore without O2 or mitochondria, you run out of NAD+
therefore lactate synthesis required to regenerate NAD+

Question 4

Lactate synthesis

Answer 4

Lactate dehydrogenase (LDH) used to turn pyruvate into lactate and vice versa impaired
also made from Alanine via transamination with alpha ketoglutarate
pyruvate regenerated from lactate in heart, liver and kidney. Required Thiamine (b1)
Prevalent in SHOCK or CONGESTIVE HEART DISEASE

Question 5

Hyperlactaemia and lactic acidosis blood concentration levels.

Answer 5

2-5mM/l below renal threshold, no change in blood pH due to buffering capacity
above 5mM/l abover renal threshold, blood pH lowered.

Question 6

Fructose metabolism,
Essential Fructosuria
Fructose intolerance

Answer 6

Fructose is metabolised into pyruvate for use.
Essential Fructosuria - fructokinase missing, no clinical signs, fructose secreted in urine
Fructose intolerance - aldolase missing, F1P accumulation in liver- damage and even death. managed by removing sucrose and fructose from diet

Question 7

Galactosaemia

Answer 7

galactokinase deficiency, rare - galactose accumulates - mild symptoms
galactose 1-p uridyl transferase deficiency - galactose and Galactose1p accumulate. Worse symptoms - liver kidney brain
Both can cause oxidative damage to lens, via NAPDH depletion, aldose reductase turns galactose to galactitol.

Question 8

G6PD deficiency

Answer 8

G6PD is an enzyme that takes G6 from glycolysis to start the pentose phosphate pathway. This pathway forms NADPH which is required for lots of reductive processes in the body. Most obviously in patients with this deficiency, oxidative protection from the NADPH is missing. NADPH replenishes glutathione which is oxidised to form a disulfide bond. This stops cysteine in haemoglobin oxidising, forming heinz bodies. Leading to haemolytic anaemia without it.