Exam 12: The Genetic Code and Transcription

It has been recently determined that the gene for Duchenne muscular dystrophy (DMD) is more than 2000 kb (kilobases) in length; however, the mRNA produced by this gene is only about 14 kb long. What is a likely cause of this discrepancy?

What two experimental procedures allowed deciphering of the ordered triplet assignments of the genetic code?

Which of the following two terms relate most closely to split genes?

Suppose that in the use of polynucleotide phosphorylase, nucleotides A and C are added in a ratio of 1A:5C. What is the probability that an AAA sequence will occur?

Significant in the deciphering of the genetic code was the discovery of the enzyme polynucleotide phosphorylase. What is this enzyme used for?

Describe how the sigma subunit (factor) of E. coli RNA polymerase participates in transcription.

The finding that virtually all organisms use the same genetic code provides the basis for declaring that the code is universal. Name at least two exceptions to such universality.

Which of the following contains the three posttranscriptional modifications often seen in the maturation of mRNA in eukaryotes?

Sidney Brenner argued that the code was nonoverlapping because he considered that coding restrictions would occur if it were overlapping. A second major argument against an overlapping code involved the effect of a single nucleotide change. In an overlapping code, how many adjacent amino acids would be affected by a point mutation? In a nonoverlapping code, how many amino acid(s) would be affected?

A class of mutations that results in multiple contiguous (side -by -side) amino acid changes in proteins is probably caused by which one of the following types of mutations?

A 3' poly -A tail and a 5' -cap are common components of prokaryotic RNAs.