Download PROTEIN SYNTHESIS QUESTIONS

PROTEIN SYNTHESIS QUESTIONS
Wednesday:
1.
What polypeptide product would you expect from a poly-G mRNA that is 30
nucleotides long? (What does poly-G mean? Many G’s, silly! You will need to
decode the mRNA using the amino acid chart from your text.)
2. The template strand of a gene contains the sequence 3’ TTCAGTCGT 5’. Draw
the nontemplate sequence and the mRNA sequence, indicating 5’ and 3’ ends of
each. Compare the two sequences.
3. Imagine that the nontemplate sequence in question 2 was traqnscribed instead
of the template sequence. Draw the mRNA sequence and translate (use amino
acid chart and pay attention to 5’ and 3’ ends). Predict how well the protein
synthesized from the nontemplate strand would function if at all.
4. What makes RNA polymerase start transcribing a gene at the right place on
the DNA in a bacterial cell? In a eukaryotic cell?
5. Suppose X-rays caused a sequence change in the TATA box of a particular
gene’s promoter. How would that affect transcription of the gene?
Thursday:
6.
In nematode worms, a gene that codes for an ATPase has two alternatives for
exon 4 and three alternatives for exon 7. How many different forms of the
protein could be made from this gene?
7. What two processes ensure that the correct amino acid is added to a growing
polypeptide chain?
8. Describe how a polypeptide to be secreted is transported to the endomembrane
system.
9. The genetic code is rich with evolutionary implications. For instance, notice
that the 20 amino acids are not randomly scattered; most amino acids are
coded for by a similar set of codons. What evolutionary explanations can be
given for this pattern?
10. Knowing that the genetic code is almost universal, a scientist uses molecular
biological methods to insert the human beta-globin gene into bacterial cells, hoping
the cells will express it and synthesize functional beta-globin protein. Instead,
the protein produced is nonfunctional and is found to contain many fewer amino
acids than does beta-globin made by a eukaryotic cell. Explain why.