Concept explainers
It’s All About Membranes. Answer each of the following questions about biological membranes in 50 words or less:
(a) What is an amphipathic molecule? Why are amphipathic molecules important constituents of membranes?
(b) Why are membranes lipid bilayers and not monolayers?
(c) What does “selectively permeable” mean?
(d) If a lipid bilayer is at least 108 times less permeable to K+ ions than it is to water, how do the K+ ions that are needed for many cellular functions get into the cell?
(e) It is often possible to predict the number of times a membrane protein crosses the membrane by determining how many short sequences of hydrophobic amino acids are present in the amino acid sequence of the protein. Explain.
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Becker's World of the Cell (9th Edition)
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