Chapter 13: The Molecular Basis of Inheritance

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

3' end; 3' end

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

Adenine and guanine; cytosine and thymine

Which of the following statements concerning the structure of DNA is correct?

Adenine forms two hydrogen bonds with thymine; guanine forms three hydrogen bonds with cytosine

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

All of the listed responses are correct. - Their chromosomes have a simpler structure. - They can interact with each other. - They have relatively small genomes. - They have short generation times.

Which of the following statements about origins of replication is correct?

All of the listed responses are correct. -Bacterial chromosomes have a single origin, but eukaryotic chromosomes have many origins. -In both prokaryotes and eukaryotes, replication proceeds in both directions from each origin. -In bacteria, the DNA sequence at the origin is recognized by specific proteins that then bind to the origin. -The two strands of DNA at the origin are separated, allowing the formation of a replication bubble.

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

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

What enzyme joins Okazaki fragments?

DNA ligase

Which of the following components is required for DNA replication?

RNA primers

Once the DNA at the replication fork is unwound by helicases, what prevents the two strands from coming back together to re-form a double helix?

Single-strand binding proteins bind the unwound DNA and prevent the double helix from re-forming.

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

TATCCA

The incorporation of an incorrect base into a DNA molecule during replication __________.

The incorporation of an incorrect base into a DNA molecule during replication __________.

Which of the following lists is in order from the entity with the smallest genome to the entity with the largest genome?

Virus, bacteria, eukaryote

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

Watson and Crick

What technique was most helpful to Watson and Crick in developing their model for the structure of DNA?

X-ray crystallography

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

attach free nucleotides to the new DNA strand

During Griffith's experiments with Streptococcus pneumoniae in mice, material from __________ bacteria transformed __________ bacteria.

heat-killed virulent; living nonvirulent

The rate of elongation of a DNA strand in prokaryotes is __________ the rate in eukaryotes.

much faster than

The "beads on a string" seen in interphase chromatin are __________.

nucleosomes

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

one error per 10,000,000,000 nucleotides

The two strands of a DNA double helix are antiparallel. This means that __________.

one strand runs in the 5' to 3' direction and the other runs in the 3' to 5' direction

The experiments of Meselson and Stahl showed that DNA __________.

replicates in a semiconservative fashion

A scientist assembles a bacteriophage with the protein coat of phage T2 and the DNA of phage T4. If this composite phage were allowed to infect a bacterium, the phages produced in the host cell would have __________.

the protein and DNA of T4

Chargaff found that in DNA samples, __________.

the ratio of A to T is close to 1:1 and the ratio of G to C is close to 1:1

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

Avery and his colleagues' 1944 experiment showed that DNA __________.

was the substance that transformed the bacteria in Griffith's experiment