Short Answer Questions - Enzymes and regulation of pathways
1. What are the units used to express the Michaelis–Menten constant (Km) of an enzyme reaction?
Concentration units, usually mmol/l.
2. What is meant by ‘long-term regulation’ of enzymes?
Long-term regulation refers to changes in the amount of enzyme.
3. What is meant by ‘short-term regulation’ of enzymes?
Short-term regulation refers to changes in the activity of an enzyme.
4. Name the regulatory enzymes of glycolysis.
Hexokinase (or glucokinase), phosphofructokinase-1, pyruvate kinase.
5. Does ATP stimulate or inhibit phosphofructokinase-1?
Both. ATP is a substrate for phosphofructokinase-1 (PFK-1) and stimulates activity at low concentrations. However, at high concentrations ATP binds to an allosteric site on PFK-1 and inhibits
6. What is the function of the carnitine shuttle?
The carnitine shuttle is needed to transport fatty acids across the inner membrane of the mitochondrion into the mitochondrial matrix.
7. What would be the metabolic consequence of impaired function of the carnitine shuttle?
Cells (especially muscle cells) would be unable to use fatty acids as a fuel. Instead they would use glucose. This would result in hypoglycaemia.
