Alterations in DNA, whether they occur by mistake during replication, or as a result of some type of damage, can lead to mutations. Mutations, however, are rare in terms of leading to actual damage to a cell. Why?
What will be an ideal response?
If DNA is damaged, the cell has the ability to detect the mutated DNA and make appropriate repairs. Ordinarily, the altered DNA is excised or the nucleotides replaced as needed. As long as the repairs are made before the cell undergoes DNA replication, altered DNA does no real harm. Even if the mutations are not fixed before replication, the altered DNA may have no effect since most genes in humans exist in the diploid condition, meaning two copies of each gene, and usually one healthy copy is typically all that is needed to ensure normal gene expression.
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Which of the following is a gastropod?
(a) clam. (b) snail. (c) squid. (d) octopus.
How is a gradient of H+ ions formed across the inner mitochondrial membrane?
A. The electron transport chain uses energy from transfer of an electron donated by NADH to pump H+ across the inner mitochondrial membrane against its electrochemical gradient. B. ATP synthase generates a H+ gradient across the inner mitochondrial membrane. C. Electrons move from NADH to a chain of proteins with lower electronegativities. D. The electron transport chain uses ATP to pump H+ across the inner mitochondria membrane against its electrochemical gradient. E. The electron transport chain of proteins contains pores that are leaky to H+.
What percentage of Florida's species are exotics?
a. 25 b. 78 c. 65 d. 10 e. 45
A solution consists of the _____ and ______
Fill in the blank(s) with the appropriate word(s).