Topic 11 Deciphering the Genetic Code Instapolls, Quizzes, and HW

Topic 11 Deciphering the Genetic Code Instapolls, Quizzes, and HW

Instapoll 1: A region of DNA has six copies of a trinucleotide repeat. During one round of replication, the template strand slips as shown in the diagram.

 

How many repeats will the DNA have if the newly synthesized strand is used as a template in the next round of replication?

4

Instapoll 2: Which of the following supplements will allow Arg-G^- autotrophs (mutants)  to grow?

Argininosuccinate and Arginine

Instapoll 3: Which of the following are frameshift suppressor mutations and Why?

Both pink m’s Both red m’s or Both blue m’s

Both blue m’s because they add or subtract in triplets which is the codon length.

You have made random-sequence synthetic RNA molecules that contains only A and C, and which contain twice as much A as C. You use these RNAs to perform in vitro translation. How many different amino acids would you find in the resulting polypeptides? And at what frequency would you expect to find Proline (Pro) in the resulting polypeptides?

6; 1/9

The ribosome binding experiment illustrated below was used to discover that the codon CUC specifies Leucine, and not Serine. Suppose you wanted to use this experimental protocol to determine whether the codon AGA specifies Arg or Glu? What would you need at the start of the experiment? (Check all that apply.)

radioactive Arginine (Arg), radioactive Glutamic acid (Glu), and AGA trinucleotides

Which of the following statements is true of trpA⁻ auxotrophs?

Of all Trp⁻ auxotrophs, only trpA⁻ mutants cannot grow on minimal medium supplemented with any intermediate in the tryptophan biosynthesis pathway; trpA⁻ auxotrophs require a tryptophan supplement.

In a particular strain of E.coli, there are two duplicated genes for a tRNA with the anticodon 3′AUG5′.  One of those two genes is mutated into a tRNA with an anticodon of 3′ AU^xm5s2U 5′ instead. Which of the following effects would you expect to observe?

Some proteins produced by these bacteria will be longer than usual.

A tRNA with the anticodon sequence 5′ IUC 3′ will not normally exist because _____________________

5′ GAU 3′ and 5′ GAC 3′ specify aspartic acid, but 5′ GAA 3′ specifies glutamic acid.

Check all of the following statements that describe nonsense suppressor mutations accurately.

They can alter the sizes of cellular proteins, 

They are mutations in tRNA genes, 

They result in a mutant tRNA that can interact with a stop codon.