AP BIOLOGY

Detailed explanation-1: -The same ligand can cause different responses in different cell types due to differences in protein expression in the different cells, where the same signal activates different signaling pathways, leading to a different response in each cell type.

Detailed explanation-2: -Cellular responses can be different in different cells depending on the internal signal transduction machinery the cell has. For example, some cells have the ability to amplify a signal by activating multiple copies of a protein inside the cell. This increases the signal from a single signaling molecule on the surface.

Detailed explanation-3: -How is it that different cells can respond in different ways to exactly the same signaling molecule even when they have identical receptors. Ans: Cells with identical receptors can respond differently to the same signal molecule because of differences in the internal machinery to which the receptors are coupled.

Detailed explanation-4: -Each hormone-receptor unit produces different cellular and body responses because each unit turns on distinct genes that code for a specific protein. Different proteins, in turn, cause unique biological responses: estrogens can stimulate uterine growth and androgens can stimulate muscle growth.