Nicotine from cigarette smoke acts as a ligand and associates with specific cells in the nervous system. Nicotine eventually produces feelings of pleasure and well-being. Below are the events that happen in the cellular response to nicotine. Place the events in the correct order to describe the steps in the signaling pathway.
A. The acetylcholine receptor is an ion channel, and, when a ligand binds, the ion channel opens.
B. An influx of ions carries the signal to the reward areas of the brain.
C. Nicotine binds to the transmembrane protein that normally binds the neurotransmitter acetylcholine.
D. The signal causes release of dopamine in the brain, which causes good feelings.
E. Nicotine is quickly eliminated from the body (causing cravings for more cigarettes to produce good feelings).
a. Nicotine is quickly eliminated from the body (causing cravings for more cigarettes to produce good feelings).
b. A, D, B, C, E
c. B, A, C, D, E
d. C, A, B, D, E
e. C, D, B, A, E
Answer: d. C, A, B, D, E
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A) The energy goes into ATP. B) The energy goes into lactic acid. C) The energy goes out of the cell as heat. D) The energy goes into electrons that directly power the cell.
__________ or __________ extend from many prokaryotic cells and serve in attachment and motility.
Fill in the blank(s) with the appropriate word(s).
Early signs or symptoms of breast cancer include:
A) a small, painless lump in the breast. B) swollen lymph glands in the axilla. C) significant weight loss and vomiting. D) nipple discharge and breast tenderness.