Exam 16: The Molecular Basis of Inheritance

Which of the following investigators was/were responsible for the following discovery? In DNA from any species, the amount of adenine equals the amount of thymine, and the amount of guanine equals the amount of cytosine.

Which of the following represents the order of increasingly higher levels of organization of chromatin?

The enzyme telomerase solves the problem of replication at the ends of linear chromosomes by which method?

E. coli cells grown on ¹⁵N medium are transferred to ¹⁴N medium and allowed to grow for two more generations (two rounds of DNA replication). DNA extracted from these cells is centrifuged. What density distribution of DNA would you expect in this experiment?

Grains represent radioactive material within the replicating eye. -In an experiment, DNA is allowed to replicate in an environment with all necessary enzymes, dATP, dCTP, dGTP, and radioactively labeled dTTP (³H thymidine)for several minutes and then switched to nonradioactive medium. It is then viewed by electron microscopy and autoradiography. The figure above represents the results. Which of the following is the most likely interpretation?

In his transformation experiments, what did Griffith observe?

Use the following list of choices for the following questions: I. helicase II. DNA polymerase III III. ligase IV. DNA polymerase I V. primase -Which of the enzymes covalently connects segments of DNA?

What is the function of topoisomerase?

Why do histones bind tightly to DNA?

Which of the following help(s)to hold the DNA strands apart while they are being replicated?

-In the late 1950s, Meselson and Stahl grew bacteria in a medium containing "heavy" nitrogen (¹⁵N)and then transferred them to a medium containing ¹⁴N. Which of the results in the figure above would be expected after one round of DNA replication in the presence of ¹⁴N?

In E. coli, there is a mutation in a gene called dnaB that alters the helicase that normally acts at the origin. Which of the following would you expect as a result of this mutation?

For a science fair project, two students decided to repeat the Hershey and Chase experiment, with modifications. They decided to label the nitrogen of the DNA, rather than the phosphate. They reasoned that each nucleotide has only one phosphate and two to five nitrogens. Thus, labeling the nitrogens would provide a stronger signal than labeling the phosphates. Why won't this experiment work?

In a linear eukaryotic chromatin sample, which of the following strands is looped into domains by scaffolding?

Use the following list of choices for the following questions: I. helicase II. DNA polymerase III III. ligase IV. DNA polymerase I V. primase -Which of the enzymes removes the RNA nucleotides from the primer and adds equivalent DNA nucleotides to the 3' end of Okazaki fragments?

Use the following list of choices for the following questions: I. helicase II. DNA polymerase III III. ligase IV. DNA polymerase I V. primase -Which of the enzymes separates the DNA strands during replication?

-A space probe returns with a culture of a microorganism found on a distant planet. Analysis shows that it is a carbon-based life-form that has DNA. You grow the cells in ¹⁵N medium for several generations and then transfer them to ¹⁴N medium. Which pattern in the figure above would you expect if the DNA was replicated in a conservative manner?

Studies of nucleosomes have shown that histones (except H1)exist in each nucleosome as two kinds of tetramers: one of 2 H2A molecules and 2 H2B molecules, and the other as 2 H3 and 2 H4 molecules. Which of the following is supported by this data?

Which of the following would you expect of a eukaryote lacking telomerase?

Which of the following statements is true of histones?