ENDOCRINE ORGANS AND RESPIRATORY SYSTEM
ENDOCRINE ORGANS
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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steroid hormones (nonpolar lipids)
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ions (small, very polar)
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glucose (large and polar)
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protein hormones (large and polar)
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Detailed explanation-1: -Some signaling molecules are able to cross the plasma membrane and bind to intracellular receptors in the cytoplasm or nucleus, whereas most bind to receptors expressed on the target cell surface.
Detailed explanation-2: -Which of the following signal molecules does not interact with cell surface receptors? Sol: (d) Testosterone.
Detailed explanation-3: -The ligand crosses the plasma membrane and binds to the receptor in the cytoplasm. The receptor then moves to the nucleus, where it binds DNA to regulate transcription.
Detailed explanation-4: -Steroids do not bind to cell surface receptors. This is because they readily cross the nonpolar cell membrane owing to their nonpolar nature. Their receptors are thus cytoplasmic molecules.