In terms of transcription regulation, the role of a helix-turn-helix is most similar to that of a(n) .
A. poly-A tail
B. guanine cap
C. sigma factor
D. zinc finger
Answer: D
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Which of the following is not true of oligonucleotide-directed mutagenesis?
A. Two complementary oligonucleotides, each identical in sequence to the cloned gene, are annealed to the opposite strands of the cloned gene. B. Two complementary oligonucleotides, each with the desired base change, are annealed to the opposite strands of the cloned gene. C. After repeated cycles of PCR, the mutation containing DNA predominates in the population. D. Nonmutant template plasmid DNA can be selectively eliminated by cleavage of the methylated template strand. E. The two annealed mutant DNA strands serve as primers of DNA synthesis in both directions around the plasmid vectors.
The figure below shows three mouse populations and their associated changes in the frequency of B, the allele for dark fur. The recessive b allele codes for white fur. After 20 generations, in which population would you be most likely to encounter a white mouse?
A. N1
B. N2
C. N3
D. There is an equal probability of encountering a white mouse in all three populations.
E. There is an equal probability of encountering a white mouse in populations N1 and N3 and this is higher than in N2.
The part of the nervous system that is composed of
two parts that are antagonistic to each other is a. the autonomic nervous system. b. the spinal cord. c. the peripheral nervous system. d. the central nervous system. e. none of these.
Which of the following statements is false regarding the characteristics of Rickettsias?
A. They are obligate intracellular parasites. B. They are the cause of Rocky Mountain Spotted Fever. C. They belong to class Alphaproteobacteria. D. They use glucose as an energy source.