Question

Which of the following is true of the ob mouse?

1) The ob mouse develops obesity at weaning.
2) The ob mouse has a fast metabolism.
3) Fat cells in the ob mouse fail to produce leptin.
4) The obesity of the ob mouse can be reversed by daily injections of insulin.
5) The ob mouse fails to secrete ghrelin.

Answer 1

Fat cells in the ob mouse fail to produce leptin, which leads to obesity due to lack of satiety signaling. The mouse has a slower metabolism due to obesity and cannot have its condition reversed with insulin injections.

Step-by-step explanation:

The statement about the ob mouse that is true is: 3) Fat cells in the ob mouse fail to produce leptin. The ob mouse is a genetically modified mouse that is used to study obesity. These mice carry a mutation that prevents their fat cells from producing leptin, which is a hormone responsible for regulating hunger and energy use. As leptin is crucial for signaling satiety, the lack of this hormone leads to uncontrolled food intake and results in obesity. Metabolism in these mice is slower due to the obesity, contrary to having a fast metabolism.

Daily injections of insulin will not reverse the obesity in these mice, as their condition is not primarily related to insulin resistance but to the absence of leptin signaling. The ob mouse also does not fail to secrete ghrelin; ghrelin is a different hormone that stimulates appetite, which works counter to leptin.