How do gene duplications promote diversity in evolution?
What will be an ideal response?
Ans: Most mutations are deleterious and would be selected against. However, if a gene is first duplicated, the duplicated copy is free to diverge, perhaps resulting in a desirable change, while the first copy retains the original function.
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Gene regulation by siRNA is ____ in eukaryotes and may have evolved originally as a ____
A. rare; way to regulate gene expression B. widespread; way to regulate gene expression C. rare; defense against mutations that may cause cancer D. widespread; defense against viruses E. rare; defense against viruses
When scientists experimentally simulated conditions near a hydrothermal vent, _____ appeared within a week
a. cells b. nucleic acids c. hydrocarbons d. amino acids e. lipid membranes
Answer the following statements true (T) or false (F)
1. Of the 20 amino acids in all organisms, essential amino acids are obtained by food consumption. 2. If a protein is denatured, its structure has been changed enough to make the protein nonfunctional. 3. Proteins store the genetic information of the cell and transmit it to the next generation. 4. When Herceptin medication is used to stop the excessive action of receptor proteins in breast cancer cells, slowing their division, the receptor proteins are within the cell nucleus where the cell is regulated. 5. Endosymbiosis theory is proposed in large part because of the resemblance of mitochondria and chloroplast structures to prokaryotes.
Of the following hominin species, which appears first in the fossil record?
A. Australopithecus afarensis D. Australopithecus garhi B. Australopithecus africanus E. Paranthropus aethiopicus C. Australopithecus anamensis