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

What are chromosomes made of?

DNA and proteins

Who conducted the X-ray diffraction studies that were key to the discovery of the structure of DNA?

Franklin

Which of the following statements best describes the eukaryotic chromosome?

It consists of a single linear molecule of double-stranded DNA plus proteins.

Which of the following is true of DNA during interphase?

It exists as chromatin and is less condensed than mitotic chromosomes. Submit

DNA is a self-replicating molecule. What accounts for this important property of DNA?

The nitrogenous bases of the double helix are paired in specific combinations: A with T and G with C. Submit

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

can be repaired by the mismatch repair system

The elongation of the leading strand during DNA synthesis __________.

depends on the action of DNA polymerase

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

heat-killed virulent: living nonvirulent

Part complete During DNA replication, which of the following enzymes separates the DNA strands during replication?

helicase

In a nucleosome, the DNA is wrapped around __________.

histones

Which of the following modifications is most likely to alter the rate at which a DNA fragment moves through a gel during electrophoresis?

increasing the length of the DNA fragment

What is an example of "recombinant DNA technology"?

introducing a human gene into a bacterial plasmid

Part complete An Okazaki fragment has which of the following arrangements?

5' RNA nucleotides, DNA nucleotides 3'

Cytosine makes up 42% of the nucleotides in a sample of DNA from an organism. Approximately what percentage of the nucleotides in this sample will be thymine?

8%

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 Submit

During DNA replication, the leading strand is synthesized continuously, whereas the lagging strand is synthesized as Okazaki fragments. Why is this so?

DNA synthesis can take place only in the 5' to 3' direction.

DNA replication is said to be semiconservative. What does this mean?

Each new double helix consists of one old and one new strand

Which of the following statements accurately describes why Taq polymerase is used in PCR?

It is heat stable and can withstand the heating step of PCR.

What is the role of DNA ligase in the elongation of the lagging strand during DNA replication?

It joins Okazaki fragments together.

What is the function of helicase in DNA replication?

It untwists the double helix and separates the two DNA strands

In his transformation experiments, what did Griffith observe?

Mixing a heat-killed pathogenic strain of bacteria with a living nonpathogenic strain can convert some of the living cells into the pathogenic form

Which of the following statements describes one difference between DNA replication in prokaryotes and DNA replication in eukaryotes?

Prokaryotic chromosomes have a single origin of replication, whereas eukaryotic chromosomes have many.

Which of the following components is required for DNA replication?

RNA primers

In the Hershey and Chase experiment that helped confirm that DNA, not protein, was the hereditary material, what was the key finding?

Radioactively labeled phosphorus was present inside the infected bacteria

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

What is meant by the description "antiparallel" regarding the two strands of nucleic acids that make up DNA

The 5' to 3' direction of one strand runs counter to the 5' to 3' direction of the other strand.

Griffith's experiments with S. pneumoniae were significant because they showed that traits could be transferred from one organism to another. What else did he find that was significant?

The transferred traits were heritable

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

Their chromosomes have a simpler structure, have relatively small genomes, short generation times and can interact with each other

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

Watson and Crick

In recombinant DNA experiments, what is used to cut pieces of DNA and what joins the resulting fragments to form recombinant DNA?

a restriction enzyme ... DNA ligase

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

adenine and guanine: cytosine and thymine

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

attach free nucleotides to the new DNA

Part complete Which of the following sets of materials is required by both eukaryotes and prokaryotes for DNA replication?

double-stranded DNA, four kinds of DNA nucleotides, primers, origins of replication Submit

The experiments of Meselson and Stahl showed that DNA __________.

it replicates in a semiconservative fashion

Gel electrophoresis separates DNA fragments on the basis of what characteristic?

length

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

much faster than

In nucleotide excision repair, damaged DNA is excised by what enzyme(s)?

nuclease

In which order do the necessary enzymes act to repair a thymine dimer by nucleotide excision repair?

nuclease, DNA polymerase, DNA ligase

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

nucleosomes

What process repairs damage to a preexisting double helix?

nucleotide excision repair

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

Which of the following enzymes synthesizes short segments of RNA?

primase

What is the function of topoisomerase?

relieving strain in the DNA ahead of the replication fork

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

single-strand binding proteins

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

What are the repetitive DNA sequences present at the ends of eukaryotic chromosomes called?

telomeres

The leading and the lagging strands of DNA formed during DNA replication differ in that

the leading strand is synthesized in the same direction as the movement of the replication fork, and the lagging strand is synthesized in the opposite direction.

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

It became apparent to Watson and Crick after completion of their model that the DNA molecule could carry a vast amount of hereditary information based on which of the following characteristics?

the sequence of bases

How is transformation in bacteria most accurately described?

the type of semiconservative replication shown by DNA

What is the function of DNA polymerase III?

to add nucleotides to the 3' end of a growing DNA strand

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

virus, bacteria, eukaryote

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

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

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

x-ray crystallography

In trying to determine whether DNA or protein is the genetic material, Hershey and Chase made use of which of the following facts?

DNA contains phosphorus, whereas protein does not

What enzyme joins Okazaki fragments?

DNA ligase

Part complete During DNA replication, which of the following enzymes removes the RNA nucleotides from the primer and adds equivalent DNA nucleotides to the 3' end of Okazaki fragments?

DNA polymerase I

Part complete Which enzyme catalyzes the elongation of a DNA strand in the 5' → 3' direction?

DNA polymerase III

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 preexisting strand.

A new DNA strand elongates only in the 5' to 3' direction because

DNA polymerase can only add nucleotides to the free 3' end.

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

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