How are comparisons of the number of base substitutions at nonsynonymous sites between genes encoding homologous proteins in different species or in different members of a gene family used to construct a molecular clock?
What will be an ideal response?
Ans: If mutations occur at a steady rate throughout evolution, then the divergence in sequence between any two genes should be proportional to the time since the genes separated. (One needs to compare genes where the time of divergence is known to calculate the divergence rate). The divergence rate for globin is 0.12% per million years. The reciprocal, the unit evolutionary period (UEP), would be 10.4 million years for a divergence of 1%. Therefore, if the divergence is known, the time since duplication can also be calculated.
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During acetyl-CoA synthesis, pyruvate is broken down into CO2 and an acetyl group. The CO2 is:
A. less oxidized than the acetyl group. B. more reduced than the acetyl group. C. more energetic than the acetyl group. D. less energetic than the acetyl group. E. None of the answer options is correct.
Any gene located on a sex chromosome is a sex-linked gene
a. true b. false
What are the potential consequences if a person has their gallbladder removed?
A. The liver will stop producing bile because it won't have any place to store it. This means that they will have a decreased ability to emulsify the fats found within the small intestine. B. The liver will stop producing bile because it won't have any place to store it. This means that they will have a decreased ability to digest the proteins found within the small intestine. C. Their body will not be able to store the excess bile produced by the liver. This means that they will have a decreased ability to emulsify the fats found within the stomach. D. Their body will not be able to store the excess bile produced by the liver. This means that they will have a decreased ability to emulsify the fats found within the small intestine.
Foreign substances like nicotine, morphine, and menthol exert their initial effects by _____
(a) killing cells immediately, exerting their physiological effects by causing cell death. (b) diffusing through cell plasma membranes and binding to transcription factors to change gene expression. (c) interacting with cell-surface receptors, causing the receptors to transduce signal inappropriately in the absence of the normal stimulus. (d) removing cell-surface receptors from the plasma membrane.