Which of these statements concerning hormone action is true?
A) Most protein and peptide hormones bind to receptors on the surface of the cell membrane.
B) The combination of a hormone with its receptor may alter the permeability of the cell membrane.
C) A hormone that combines with a receptor in the cell membrane may act as a first messenger.
D) Cyclic AMP (cAMP) functions as a second messenger.
E) All of these are true statements.

Question

Quizplus · Accepted Answer

All of the statements are true.

A) Most protein and peptide hormones bind to receptors on the surface of the cell membrane. This is true because these hormones are unable to pass through the cell membrane due to their large size and polarity.
B) The combination of a hormone with its receptor may alter the permeability of the cell membrane. This is true because the binding of the hormone to the receptor can cause a conformational change in the receptor which can lead to opening or closing of ion channels or other membrane transporters, thus altering the membrane permeability.
C) A hormone that combines with a receptor in the cell membrane may act as a first messenger. This is true because the binding of the hormone to the receptor can trigger a series of signaling events within the cell, leading to the activation of enzymes, second messengers, and other intracellular signaling molecules.
D) Cyclic AMP (cAMP) functions as a second messenger. This is true because cAMP is a common second messenger in many intracellular signaling pathways. It is generated by the activation of adenylyl cyclase in response to the binding of certain hormones to their receptors, and it can then go on to activate a variety of downstream effectors, including protein kinases and ion channels.

Which of These Statements Concerning Hormone Action Is True