MCB150: Lecture 19 Post-Class Questions
How did the P site of the ribosome get its name?
It is where the polypeptide chain attached to the tRNA is transferred to the aminoacyl tRNA for peptide-bond formation.
What would occur if a mutation caused an aminoacyl-tRNA synthetase to recognize both its normal amino acid and a different one?
One or more codons would sometimes be misread.[The tRNA(s) recognized by this aminocacyl-tRNA synthetase could be attached to either amino acid, so the corresponding codon(s) could be read as either the correct or incorrect amino acid]
An experimenter has altered the 3' end of the tRNA corresponding to the amino acid methionine in such a way as to remove the 3' bases AC. Which of the following hypotheses describes the most likely result?
The amino acid methionine will not become covalently bound.
In Figure 17.11, what would the graphed results look like if the null hypothesis were correct? (http://session.masteringbiology.com/problemAsset/1629846/1/17.11.jpg)
The gray curve would be horizontal at 300 counts/minute and the green curve would be horizontal at zero counts/minute (i.e., along the x-axis).[If aminoacyl-tRNAs do not transfer amino acids to growing polypeptides, the distribution of radioactivity between these two types of molecules would not change over time]
What type of bonding is responsible for maintaining the shape of the tRNA molecule shown in the figure above? (http://session.masteringbiology.com/problemAsset/1739884/1/0315.jpg)
hydrogen bonding between base pairs
Shine-Delgarno sequences are present in mRNAs of
prokaryotes.
Which of the following is the first event to take place in translation in eukaryotes?
the small subunit of the ribosome recognizes and attaches to the 5' cap of mRNA
One reason that prokaryotic genes do not contain introns is that
translation sometimes begins before transcription has been completed because prokaryotes do not have a nucleus.
A mutant bacterial cell has a defective aminoacyl-tRNA synthetase that attaches a lysine to tRNAs with the anticodon AAA instead of the normal phenylalanine. The consequence of this for the cell will be that _____.
proteins in the cell will include lysine instead of phenylalanine at amino acid positions specified by the codon UUU.
