Ch 12 HW

Why does DNA synthesis only proceed in the 5¢ to 3¢ direction?

Because DNA polymerases can only add nucleotides to the 3¢ end of a polynucleotide strand.

Okazaki fragments are joined together by:

DNA ligase.

Which of the following adds new nucleotides to a growing DNA chain?

DNA polymerase

Which of the following statements concerning nucleotide excision repair is FALSE?

It is a type of mismatch repair.

Why is DNA able to store large amounts of information?

Its nucleotides can be arranged in a large number of possible sequences.

Who first confirmed that the replication of DNA was semiconservative?

Meselson and Stahl

Meselson and Stahl separated DNA from different generations using:

None of these.

Use the figure to answer the corresponding question(s). Refer to Figure 12-2. The structures represented by the letter E are called:

Okazaki fragments.

How are the chromosomes of a eukaryote cell replicated?

The linear DNA molecules are replicated from multiple origins of replication bidirectionally.

Use the figure to answer the corresponding question(s). The portion of the molecule in box 5 of Figure 12-1 is:

a phosphate.

Use the figure to answer the corresponding question(s). The portion of the molecule in box 3 of Figure 12-1 is:

a purine.

The 5¢ end of each Okazaki fragment begins with:

a separate RNA primer.

Use the figure to answer the corresponding question(s). Refer to Figure 12-2. The correct designation for the DNA strand labeled C is:

a strand serving as a template.

If DNA replication rejoined the 2 parental strands, it would be termed:

conservative.

Chargaff determined that DNA from any source contains about the same amount of guanine as __________.

cytosine

Hydrogen bonds can form between guanine and __________, and between adenine and __________.

cytosine; thymine

Use the figure to answer the corresponding question(s). Refer to Figure 12-2. The segments labeled F are responsible for:

initiating DNA synthesis.

A replication fork:

is a Y-shaped structure where both DNA strands are replicated simultaneously.

In DNA replication, the lagging strand:

is synthesized as a series of Okazaki fragments

The DNA strand that is replicated smoothly and continuously is called the:

leading strand.

Use the figure to answer the corresponding question(s). Refer to Figure 12-2. The enzyme represented by the letter D is responsible for:

linking short DNA segments.

DNA primase is the enzyme responsible for:

making short strands of RNA at the site of replication initiation.

In replication, once the DNA strands have been separated, reformation of the double helix is prevented by:

single-strand binding proteins.

The information carried by DNA is incorporated in a code specified by the:

specific nucleotide sequence of the DNA molecule.

The two molecules that alternate to form the backbone of a polynucleotide chain are:

sugar and phosphate.

The ends of eukaryotic chromosomes can be lengthened by:

telomerase.

When cultured normal human cells were infected with a virus that carried the genes that coded for a subunit of telomerase:

the cells underwent more cell divisions than normal.

X-ray diffraction studies are used to determine:

the distances between atoms of molecules.

The main reason scientists thought that proteins, rather than DNA, were the carriers of genetic material in the cell was:

the large number of possible amino acid combinations.

When a DNA molecule containing a wrong base at one location in one strand is replicated:

the mutation is copied into one of the two daughter molecules.

When DNA copies itself,

the two strands separate and both strands serve as templates.

Enzymes called __________ form breaks in the DNA molecules to prevent the formation of knots in the DNA helix during replication.

topoisomerases

What prevents knot formation in replicating DNA?

topoisomerases

The final product of DNA replication is:

two DNA molecules, each of which contains one new and one old DNA strand

X-ray crystallography showed that DNA:

was a helix

In the experiments of Griffith, the conversion of nonlethal R-strain bacteria to lethal S-strain bacteria:

was an example of the genetic exchange known as transformation.

Use the figure to answer the corresponding question(s). In Figure 12-1, the portion of the molecule in box __________ is a pyrimidine.

1

Which of the following nucleotide sequences represents the complement to the DNA strand 5¢ - AGATCCG- 3¢?

3¢ - TCTAGGC- 5¢

Which of the following best describes semiconservative replication?

A DNA molecule consists of one parental strand and one new strand.

The first experimenters to use Griffith's transformation assay to identify the genetic material were:

Avery, MacLeod, and McCarty.

Which of the following causes the unwinding of the DNA double helix?

DNA helicase

Which of the following statements about DNA is false?

DNA is only found in eukaryotic cells.

The bacteriophages used in Alfred Hershey's and Martha Chase's experiments showed that:

DNA was injected into bacteria.

__________ used x-ray diffraction to provide images of DNA.

Franklin

__________, the ends of eukaryotic chromosomes, shorten with every cell replication event.

Telomeres

How is the chromosome of a bacterial cell replicated?

The circular DNA molecule is replicated from one origin of replication bidirectionally.

__________ determined the structure of the molecule DNA.

Watson and Crick

Two chains of DNA must run in __________ direction(s) and must be __________ if they are to bond with each other.

antiparallel; complementary

Mismatch repair occurs when

enzymes remove incorrectly-paired nucleotides.

Cancerous cells differ from noncancerous cells in that cancerous cells:

can maintain telomere length as they divide.