Chapter 17 Bio

Which of the following is not true of RNA processing? A) Exons are cut out before mRNA leaves the nucleus. B) Nucleotides may be added at both ends of the RNA. C) Ribozymes may function in RNA splicing. D) RNA splicing can be catalyzed by spliceosomes. E) A primary transcript is often much longer than the final RNA molecule that leaves the nucleus.

A) Exons are cut out before mRNA leaves the nucleus.

The anticodon of a particular tRNA molecule is A) complementary to the corresponding mRNA codon. B) complementary to the corresponding triplet in rRNA. C) the part of tRNA that bonds to a specific amino acid. D) changeable, depending on the amino acid that attaches to the tRNA. E) catalytic, making the tRNA a ribozyme.

A) complementary to the corresponding mRNA codon.

Which component is not directly involved in translation? A) mRNA B) DNA C) tRNA D) ribosomes E) GTP

B) DNA

In eukaryotic cells, transcription cannot begin until A) the two DNA strands have completely separated and exposed the promoter. B) several transcription factors have bound to the promoter. C) the 5' caps are removed from the mRNA. D) the DNA introns are removed from the template. E) DNA nucleases have isolated the transcription unit.

B) several transcription factors have bound to the promoter.

Which of the following is not true of a codon? A) It consists of three nucleotides. B) It may code for the same amino acid as another codon. C) It never codes for more than one amino acid. D) It extends from one end of a tRNA molecule. E) It is the basic unit of the genetic code.

D) It extends from one end of a tRNA molecule.

Which of the following mutations would be most likely to have a harmful effect on an organism? A) a nucleotide-pair substitution B) a deletion of three nucleotides near the middle of a gene C) a single nucleotide deletion in the middle of an intron D) a single nucleotide deletion near the end of the coding sequence E) a single nucleotide insertion downstream of, and close to, the start of the coding sequence

E) a single nucleotide insertion downstream of, and close to, the start of the coding sequence