Of the following statements, which best explains why cells must accumulate multi
ID: 3482107 • Letter: O
Question
Of the following statements, which best explains why cells must accumulate multiple mutations before they become cancerous?
A. All eukaryotes, regardless of complexity, have only a handful of genes that control the process of cell division. The proteins coded by these genes are extremely complex, and each has long stretches of amino acid sequences. If only a few of the amino acids in these sequences are incorrect, the protein retains its ability to function normally. Therefore, even a single cell cycle control gene must accumulate dozens of mutations before its corresponding protein becomes nonfunctional.
B. All eukaryotes, regardless of complexity, have approximately 60 cell cycle control genes that suppress inappropriate cell division. If one of these genes acquires a mutation that results in manufacture of a nonfunctional protein, the remaining proliferation-suppressing genes ramp up their rates of protein production to counteract this deficit. This process continues until the number of mutated proliferation-suppressing genes exceeds the number of nonmutated proliferation-suppressing genes.
C. All eukaryotes, regardless of complexity, have multiple genes that control the process of cell division. Some of these genes promote cell proliferation, whereas others suppress it. In addition, many of the genes in each class have overlapping functions. Therefore, if only a few of its cell cycle control genes are mutated, a cell will likely suffer few, if any, ill effects because it still has other nonmutated genes that either counteract the effects of the mutant genes or mimic the normal functions of these genes.
D. All prokaryotes, regardless of complexity, have multiple genes that promote cell proliferation. Each of these genes has a corresponding gene that directly counteracts it. Whenever a particular proliferation-promoting gene acquires a mutation, the cell senses this change and automatically disables the corresponding proliferation-suppressing gene so that homeostasis is maintained. As more and more mutations accumulate, however, the cell loses its ability to disable specific genes at a fast enough rate.
Explanation / Answer
Option C is correct. There are variety of genes which are involved in cell cycle. Some of them promote cell proliferation and some of them inhibit cell proliferation. Thus a balance is maintained. But a number of mutation cause a permanent effective change which results in cancerous cells.
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