What is the wobble hypothesis, and what implications does it have for base-pairing rules and selective pressure on codons?
What will be an ideal response?
The wobble hypothesis refers to the degeneracy at the third nucleotide position of a codon, in which the base at the 5' of the tRNA anticodon can pair with more than one type of base at the 3' end of the codon. For example, the same leucine tRNA molecule with anticodon GAG can read two different leucine codons (CUC and CUU). This allows for neutral mutations to occur in genes at the third position, but not the first or second, of a codon. Therefore, there is said to be higher selective pressure on the first and second positions in a codon, causing mutations at those positions to be much more rare.
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Members of the genus Micrococcus are usually ________.
A. microaerophilic B. facultatively anaerobic C. aerobic D. anaerobic
In reabsorption
a. plasma proteins are returned to the blood. b. excess hydrogen ions are removed from the blood. c. excess water is passed on to the urine. d. nutrients and ions are selectively returned to the blood. e. drugs and foreign substances are passed into the urine
Reciprocal innveration means that the ____
a. antagonist muscle groups contract at the same time b. antagonist muscle groups relax at the same time c. antagonist muscle groups alternate contraction and relaxation d. synergistic muscle groups contract at the same time e. synergistic muscle groups relax at the same time
What is the usual pH of stomach acids?
a. 2 b. 7 c. 10 d. 12