Exam 13: The Genetic Code and Transcription

When considering the initiation of transcription, one often finds consensus sequences located in the region of the DNA where RNA polymerase(s) binds. Which of the following is a common consensus sequence?

What is the initiator triplet in both prokaryotes and eukaryotes? What amino acid is recruited by this triplet?

Transcription factors function to help move ribosomes along the mRNA.

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?

From the late 1950s to the mid-1960s, numerous experiments using in vitro cell-free systems provided information on the nature of the genetic code. Briefly outline significant experiments in the determination of the genetic code.

The code is nonoverlapping, meaning that, assuming "standard translation," a given base participates in the specification of one and only one amino acid.

When examining the genetic code, it is apparent that ________.

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

The enzyme polynucleotide phosphorylase is capable of generating a random assembly of ribonucleotides.

In eukaryotes, which three factors appear to encourage the specific association of RNA polymerase(s) to a specific region of DNA?

What is meant by punctuation in terms of the genetic code?

List four base triplets that are clearly responsible for punctuation (initiation, termination).

Heterogeneous nuclear RNA is a primary transcript in eukaryotes that is processed prior to involvement in translation.

What is meant by the term heterogeneous nuclear RNA (hnRNA)?

"Breaking the genetic code" has been referred to as one of the most significant scientific achievements in modern times. Describe (in outline or brief statement form) the procedures used to break the code.

The relationship between a gene and a messenger RNA is that ________.

In the context of molecular genetics, how does one reconcile the terms overlapping genes and nonoverlapping code?

What is polycistronic mRNA?

A 5′-cap describes the addition of a base, usually thymine, to the 5′ end of a completed peptide.

In 1964, Nirenberg and Leder used the triplet binding assay to determine specific codon assignments. A complex of which of the following components was trapped in the nitrocellulose filter?