Biology-Chapter 9-Foundations

Animation 9.1: In the Hershey-Chase experiment, which radioisotopes were used to label which biomolecules that make up a virus? A) 14C in carbohydrates; 15N in nucleic acids B) 32P in nucleic acids; 35S in proteins C) 15N in proteins; 3H in lipids D) 35S in nucleic acids; 32P in proteins

32P in nucleic acids; 35S in proteins

For DNA replication to take place, the DNA polymerase must interact with all of the following except A) dNTPs. B) a free 3ʹ OH group of an existing strand of DNA or RNA C) .a template strand of DNA. D) DNA ligase.

DNA ligase.

Why do eukaryotes typically have multiple origins of replication, while most prokaryotes typically have just one? A) Eukaryotes are diploid, while prokaryotes are haploid. B) Eukaryotes have a less efficient DNA polymerase. C) Eukaryotes have much larger genomes. D) Eukaryotes don't have DNA helicase. E) Eukaryotes don't have Okazaki fragments.

Eukaryotes have much larger genomes.

Animation 9.1: Suppose the results of the Hershey-Chase experiment had turned out differently than they did. A hypothetical set of data that might have resulted is shown in the table. The + symbol indicates one unit of radioactivity and the - symbol indicates a lack of radioactivity above the normal background levels. Which conclusion fits these data? A) Genetic information is contained in protein. B) Genetic information is contained in DNA. C) The results are inconclusive about whether genetic information is contained in DNA or protein. D) Genetic information is contained in neither DNA nor protein.

Genetic information is contained in protein.

Animation 9.2: If the conservative model had been correct, how many generations of bacterial cell division would have had to pass before Meselson and Stahl would have observed evidence of a band in the CsCl gradient corresponding to a hybrid DNA molecule containing both 14N and 15N? A) 4 generations B) No generations; a hybrid would never form. C) 1 generation D) More than 10 generations

No generations; a hybrid would never form.

Which statement about DNA structure is false? A) It has a uniform diameter. B) It is a double-stranded helix. C) It is antiparallel (the two strands run in opposite directions). D) It is a right-handed helix. E) The 3′ end is phosphorylated.

The 3′ end is phosphorylated.

Animation 9.2: How would both the results of the Hershey-Chase experiment and the conclusions drawn have been different if the viral DNA had been associated with proteins that were transmitted along with the DNA during infection of the bacterial host cells? A) The bacterial pellet would have contained the phosphorus-32 isotope, making it clear that DNA must be the genetic material. B) The supernatant would have contained only the sulfur-35 isotope, making it clear that protein cannot be the genetic material. C) The bacterial pellet would have contained both isotopes, making it unclear which substance was the genetic material. D) The results and conclusions would have been the same as what Hershey and Chase found.

The bacterial pellet would have contained both isotopes, making it unclear which substance was the genetic material.

Animation 9.4: Ligases are enzymes that link two DNA fragments together. Suppose a bacterium develops a mutation in the ligase gene needed for DNA replication. This mutation results in an inactive form of the enzyme. What outcome can you expect for this bacterium and why? A) The bacterium will replicate itself slowly because only one DNA strand will result from the replication process instead of two. B) The bacterium will not be able to replicate itself because no DNA strands will result from the replication process. C) The bacterium will replicate itself slowly because the two strands of parental DNA will have to be replicated at different times. D) The bacterium will not be able to replicate itself because only one DNA strand will result from the replication process instead of two.

The bacterium will not be able to replicate itself because only one DNA strand will result from the replication process instead of two.

A point mutation A) is always silent. B) is a change in a single nucleotide of DNA. C) is not transmitted to daughter cells. D) can only occur during DNA replication. E) does not occur in noncoding regions of DNA.

is a change in a single nucleotide of DNA.

In DNA replication, at the _______, the exposed 3′ end gets farther and farther away from the fork as replication proceeds. A) primer B) DNA polymerase C) lagging strand D) leading strand E) Okazaki fragments

lagging strand

The expression of the enzyme _______ is largely restricted to stem cells and gametes. However, it is expressed in 90 percent of human cancers and may be responsible for their ability to survive continuous division. A) topoisomerase B) RNA polymerase C) helicase D) DNA polymerase E) telomerase

telomerase

The strands that make up DNA are antiparallel. This means that A) one strand is positively charged, and the other is negatively charged. B) the twisting of the DNA molecule has shifted the two strands. C) purines bond with purines and pyrimidines bond with pyrimidines. D) the base pairings create unequal spacing between the two DNA strands. E) the 5′-to-3′ direction of one strand runs opposite to the 5′-to-3′ direction of the other strand.

the 5′-to-3′ direction of one strand runs opposite to the 5′-to-3′ direction of the other strand.

Chargaff's rule states that A) DNA must be replicated before a cell can divide. B) only nucleic acids enter the cell during infection. C) viruses enter cells without their protein coat. D) the amount of cytosine equals the amount of guanine. E) only protein from the infecting phage can also be detected in progeny phage.

the amount of cytosine equals the amount of guanine.

DNA replication in eukaryotes differs from replication in bacteria because A) synthesis of the new DNA strand is from 3′ to 5′ in eukaryotes and from 5′ to 3′ in bacteria. B) synthesis of the new DNA strand is from 5′ to 3′ in eukaryotes and is random in prokaryotes. C) there are many origins of replication in each eukaryotic chromosome and only one in bacterial DNA. D) synthesis of the new DNA strand is from 5′ to 3′ in eukaryotes and from 3′ to 5′ in bacteria. E) Okazaki fragments are produced in eukaryotic DNA replication but not in prokaryotic DNA replication.

there are many origins of replication in each eukaryotic chromosome and only one in bacterial DNA.

A silent mutation A) results in a protein that is truncated from the N terminal end. B) is the result of a change in a codon for an amino acid in a protein to a stop codon. C) would likely not affect the activity of a protein. D) would not affect the primary structure of a protein. E) results in a shorter mRNA transcript of the gene.

would likely not affect the activity of a protein.