Learning: Chapter 16: The Molecular Basis of Inheritance

Griffith showed that dead __________ cells __________ living __________ cells into living __________ cells.

pathogenic; transform; nonpathogenic; pathogenic

The unwinding of DNA at the replication fork causes twisting and strain in the DNA ahead of the fork, which is relieved by an enzyme called __________.

topoisomerase

Which description of DNA replication is correct?

Helicases separate the two strands of the double helix, and DNA polymerases then construct two new strands using each of the original strands as templates.

What is the major difference between bacterial chromosomes and eukaryotic chromosomes?

Bacteria have a single circular chromosome whereas eukaryotes have several linear chromosomes.

DNA replication begins at a site called the origin of replication, forming a bubble, which is followed by a __________, where parental strands are unwound by __________.

replication fork; helicases

In DNA, the two purines are __________, and the two pyrimidines are __________.

adenine and guanine; cytosine and thymine

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

Why were many of the early experiments on DNA carried out on viruses and bacteria?

• They can interact with each other.

• They have relatively small genomes.

• They have short generation times.

• Their chromosomes have a simpler structure.

When __________ form after an exposure to ultraviolet (UV) light, a __________ can remove the damaged nucleotides and replace them with normal nucleotides.

thymidine dimers; nucleotide excision repair enzyme

Which of the following components is required for DNA replication?

RNA primer

Evidence to support that DNA strands run antiparallel to each other includes all of the following except __________.

that the sugar-phosphate backbones are to the inside of the molecule

In bacterial DNA replication of the lagging strand, __________ is required for the synthesis of a new DNA strand whereas __________ is required for removing the RNA primer and replacing it with DNA nucleotides.

DNA polymerase III; DNA polymerase I

The overall error rate in the completed DNA molecule is approximately __________.

1 error per 10,000,000,000 nucleotides

X-ray diffraction images produced by __________ showed that DNA is a __________.

Franklin; double helix

Proteins that are involved in packaging the eukaryotic chromosome into “beads” called __________ are __________.

nucleosomes; histones

Of the three alternative models of DNA replication, which are the __________ models, the one that explains how DNA replicates is the __________ model.

conservative, semiconservative, and dispersive; semiconservative

The 5ꞌ end of a DNA strand always has a free __________ group while the 3ꞌ end always has a free __________ group.

phosphate; hydroxyl

One strand of a DNA molecule has the base sequence 5'-ATAGGT-3'. The complementary base sequence on the other strand of DNA will be 3'-__________-5'.

TATCCA

Who is credited with explaining the structure of the DNA double helix?

Watson and Crick

A virus that infects bacteria is called a __________, which is made up of the macromolecules __________ and __________.

bacteriophage; DNA; protein

In the famous Hershey and Chase “blender experiment,” radioactive sulfur was used to label __________, and radioactive phosphorus was used to label __________, demonstrating that the genetic material of a bacteriophage is __________.

protein; DNA; DNA

The information in DNA is contained in __________.

the sequence of nucleotides along the length of the two strands of the DNA molecule

Telomeres are __________.

repeating noncoding sequences at the ends of linear eukaryotic chromosomes

The role of DNA polymerases in DNA replication is to __________.

attach free nucleotides to the new DNA strand

Chargaff analyzed DNA and found that the numbers of adenine molecules is approximately equal to the numbers of __________ molecules and that the numbers of __________ molecules is approximately equal to the numbers of __________ molecules.

thymine; guanine; cytosine

The two sugar-phosphate strands that form the rungs of a DNA double helix are joined to each other through __________.

hydrogen bonds between nucleotide bases

In DNA replication, the next nucleotide is incorporated into the growing polymer at the __________ of the molecule by an enzyme called __________.

3ꞌ (hydroxyl) end; DNA polymerase

Replication of the lagging strand of DNA is accomplished by repeatedly making __________ followed by 1,000–2,000 nucleotide segments called __________.

short RNA primers; Okazaki fragments

DNA polymerase adds nucleotides to the __________ of the leading strands, and to the __________ of the lagging strands (Okazaki fragments).

3' end; 3' end