Question

*Consider a mutant liver cell isolated from a liver cancer patient. This cell contains about 104 molecules of active protein kinase A, even in the absence of epinephrine. What is a reasonable genetic explanation?*

The cell's phosphorylase kinase gene has a mutation that makes the kinase active all of the time.

The cell's glycogen phosphorylase gene has a mutation that makes the phosphorylase active all of the time.

The cell's adenylate cyclase gene has a mutation that makes the cyclase active all of the time.

The cell's adenylate cyclase gene has a mutation that makes the cyclase inactive all of the time.

Answer 1

A reasonable genetic explanation for a mutant liver cell containing a high level of active protein kinase A (PKA) even in the absence of epinephrine is that the cell's adenylate cyclase gene has a mutation that makes the cyclase active all of the time.

Step-by-step explanation:

A reasonable genetic explanation for a mutant liver cell containing about 10^4 molecules of active protein kinase A (PKA) even in the absence of epinephrine would be that the cell's adenylate cyclase gene has a mutation that makes the cyclase active all of the time.

Adenylate cyclase is responsible for converting ATP to cyclic AMP (CAMP), which activates PKA. In normal cells, the activation of adenylate cyclase is triggered by hormones like epinephrine. However, in this mutant cell, the cyclase is constantly active, leading to a high level of active PKA.

This constant activation of PKA can dysregulate cellular processes, including the phosphorylation of enzymes involved in glycogen metabolism. This could explain the high level of active PKA and its impact on the breakdown and synthesis of glycogen in the mutant liver cell.