Biology, Eighth Edition (Raven)

Chapter 15: Genes and How They Work

Pre Test

True of False: The central dogma of molecular biology states that DNA becomes RNA, which then becomes protein. (p. 279)
Which of the following pieces of evidence is among the strongest that supports the idea that all organisms have arisen from a single distant ancestor? (p. 281)
A)All organisms use DNA to store their information.
B)The genetic code is universally a triplet code.
C)The amino acids specified by particular triplets are almost always identical between any two organisms.
D)DNA encodes information for RNA, which directs protein synthesis.
E)The genetic code is degenerate but specific.
The region of a gene which "tells" RNA polymerase where the genetic message is located is called the (p. 283)
C)transcription factor.
D)start codon.
Using an electron microscope, you can view enzymes and organelles in a cell, including those involved with gene expression. How could you tell that a particular sample is a prokaryotic cell rather than a eukaryotic cell? (p. 286)
A)You could see that the nucleotides in the promoter are different in prokaryotes and eukaryotes.
B)You can see the actual genes, and they are more widely-spaced apart in eukaryotes than prokaryotes.
C)Prokaryotic ribosomes look different than eukaryotic ones.
D)You would be able to see ribosomes translating mRNA that was still being synthesized by RNA polymerase.
E)You can see that prokaryotic mRNA does not contain introns.
How might a molecular biologist most easily purify mRNA from all the other kinds of RNA in a eukaryotic cell? (p. 288)
A)She could create a filter covered with long poly-T sequences and run a cell extract over it. The tails of mRNA would base-pair with the filter and be retained, while all the other types of RNA would be rinsed off.
B)Enzymes that are specific to tRNA and rRNA could be engineered and digest everything except the mRNA of interest.
C)The sequenced genome can be analyzed and all the regions that encode protein could be used to make synthetic mRNA for analysis.
D)The methyl-G cap could be magnetized and made to adhere to a pellet in a test tube.
E)After splicing, the mRNA becomes short enough to make it distinguishable from other RNA in the cell. These could be filtered out.
If pre-mRNA is hybridized with mature mRNA, regions loop out and can be viewed with an electron microscope. What do the looped out regions represent? (p. 289)
A)excised introns
B)introns to be excised later
C)exons in the pre-mRNA
D)exons that are in the process of being fused together
E)regions of the poly-A tail in the pre-mRNA
True or false: connection of an amino acid to a tRNA is a spontaneous reaction (p. 291)
"Wobble" pairing is largely responsible for (p. 294)
A)the redundancy of the genetic code.
B)conservation of the genetic message.
C)the large variety of amino acids encoded by the genetic code.
D)the excess of different kinds of tRNA that are required for all the amino acids.
E)connection of an amino group to a carboxyl group during peptide bond formation.
Which of the following events are found in BOTH transcription and translation? (p. 296)
  1. Elongation
  2. Initiation
  3. Peptide bond synthesis
  4. Splicing
  5. Termination
A)I and IV
B)I, II, and III
C)I, III, and V
D)I, II and V
E)All steps are found in transcription and translation.
A nonsense mutation typically involves (p. 298)
A)confusion of which amino acids go where in the polypeptide chain.
B)expansions of the ends of chromosomes due to repeated nucleotides.
C)inappropriate termination of translation early in the "reading frame".
D)duplication of a region of a chromosome.
E)a mistake that causes a portion of a chromosome to "flip" in orientation.
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