Chapter 16

The elongation of the leading strand during DNA synthesis

depends on the action of DNA polymerase.

In a nucleosome, the DNA is wrapped around

histones.

In analyzing the number of different bases in a DNA sample, which result would be consistent with the base-pairing rules?

A+G=C+T.

A student isolates, purifies, and combines in a test tube a variety of molecules needed for DNA replication. When she adds some DNA to the mixture, replication occurs, but each DNA molecule consists of a normal strand paired with numerous segments of DNA a few hundred nucleotides long. What has she probably left out of the mixture?

DNA ligase

What is the basis for the difference in how the leading and lagging strands of DNA molecules are synthesized?

DNA polymerase can join new nucleotides only to the 3' end of a pre-existing strand, and the strands are antiparallel.

The spontaneous loss of amino groups from adenine in DNA results in hypoxanthine, an uncommon base, opposite thymine. What combination of proteins could repair such damage?

nuclease, DNA polymerase, DNA ligase

E. coli cells grown on medium are transferred to 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?

one low-density and one intermediate-density band

In his work with pneumonia-causing bacteria and mice, Griffith found that

the protein coat from pathogenic cells was able to transform nonpathogenic cells.