Hello there! My name is Sri!
First, remember that Type I and II diabetes both have different causes!
Type I diabetes is characteristic of little to no insulin production, due to the destruction of the majority of the pancreatic ß-cells, which make insulin.
Type II diabetes, however, is when insulin is produced normally by the ß-cells, but the insulin receptors located on the liver and other vital organs are resistant or insensitive to the effects of insulin.
Because of this, blood glucose levels will rise after a meal, because the GLUT4 receptors are not receiving a signal from the insulin receptor that tells the GLUT4 receptor to open up and allow blood glucose to enter the adipose (fat) or muscle tissue, where the GLUT4 receptor is located.
Based on this reasoning, the answer to your question will be A.
A. Receptors are dynamic - the receptor is not binding as tightly to insulin and so a signal is not being produced by the target cell
Let's see why!
Since Type II diabetes is characterized by resistance of the insulin receptor to insulin, it would be correct to say that the receptor is not binding as strongly to insulin, which in turn is not producing the target cell signal (adipose/muscle cell) that will take in blood glucose via GLUT4 transporters.
Now, let's see why the other answers are wrong!
B. Receptors can be blocked - the insulin receptor is no longer opening and recognizing insulin
This is false, because in the question it specifically says "insulin continues to bind to insulin receptors."
C. Receptors are dynamic - there are fewer insulin receptor proteins on the target cells
This is false, because in the question it specifically says "because the amount of insulin receptor proteins are not reduced"
D. Receptors can be blocked - a secondary molecule is competitively binding insulin receptors
If a secondary molecule is competitively binding insulin receptors, this would be via an agonist, a molecule that can bind to the insulin receptor location where insulin binds to. In most cases, this agonist would be in the form of a drug or other pharmaceutical compound. This is not most likely occurring, as the question says, so we can eliminate it.
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