Photo AI
Describe the role of glucagon in gluconeogenesis - AQA - A-Level Biology - Question 5 - 2019 - Paper 1
Question 5
Describe the role of glucagon in gluconeogenesis. Do not include in your answer details on the second messenger model of glucagon action. The gene that codes for g... show full transcript
Worked Solution & Example Answer:Describe the role of glucagon in gluconeogenesis - AQA - A-Level Biology - Question 5 - 2019 - Paper 1
Step 1
Describe the role of glucagon in gluconeogenesis.
Answer
Glucagon plays a critical role in gluconeogenesis, which is the process of producing glucose from non-carbohydrate sources. It attaches to receptors on target cells and stimulates enzymes that convert glycerol and amino acids into glucose. This increase in glucose availability helps raise blood sugar levels, particularly during fasting or intense exercise.
Step 2
Use this information to calculate the length in micrometres (µm) of the gene for glucagon.
Answer
First, convert kilobases to base pairs:
9.531 kilobases = 9,531 base pairs.
Next, calculate the number of complete turns in the helix:
Number of turns = total base pairs / base pairs per turn = 9,531 / 10 = 953.1 turns.
Now, calculate the total length of the gene: Length (nm) = number of turns imes length of one turn (nm) = 953.1 imes 3.4 nm = 3,236.54 nm.
Convert to micrometres (µm): 3,236.54 nm = 3.23654 µm, rounded to 3 significant figures gives 3.24 µm.
Step 3
Explain how increasing a cell's sensitivity to insulin will lower the blood glucose concentration.
Answer
Increasing a cell's sensitivity to insulin enhances its ability to uptake glucose from the bloodstream. When insulin binds to its receptors, it triggers a series of intracellular processes that facilitate the transport of glucose into the cell via channel or transport proteins. This reduces the concentration of glucose in the bloodstream, thereby lowering blood glucose levels.
Step 4
Explain how inhibiting adenylate cyclase may help to lower the blood glucose concentration.
Answer
Inhibiting adenylate cyclase reduces the conversion of ATP to cyclic AMP (cAMP). Since cAMP acts as a secondary messenger in various signaling pathways, its decrease can lead to reduced activity of pathways that promote gluconeogenesis and glycogenolysis. Consequently, less glucose is released into the bloodstream, which aids in lowering blood glucose concentration.