Chapter 13 - AP Bio

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How many DNA molecules would there be after four rounds of PCR if the initial reaction mixture contained two molecules?

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

The reason for using Taq polymerase for PCR is that

nucleotide excision repair

What process repairs damage to a preexisting double helix?

DNA is usually double-stranded, whereas RNA is usually single-stranded.

Which of these is a difference between a DNA and an RNA molecule?

D

Which of these is responsible for catalyzing the formation of an RNA primer?

thymine

Which of these nitrogenous bases is found in DNA but not in RNA?

Phosphate groups

Which part of a deoxynucleoside triphosphate (dNTP) molecule provides the energy for DNA synthesis?

Franklin

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

Hershey and Chase

Who demonstrated that DNA is the genetic material of the T2 phage?

Histones are positively charged, and DNA is negatively charged.

Why do histones bind tightly to DNA?

DNA polymerase can assemble DNA only in the 5' to 3' direction

Why is the new DNA strand complementary to the 3' to 5' strands assembled in short segments?

Approximately 28%

You can use Chargaff's rules to predict the percentage of one or more bases in the DNA of a species if at least one value is known. What is the %T in wheat DNA?

assimilation of external DNA into a cell

How do we describe transformation in bacteria?

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

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

C

A nitrogenous base is indicated by the letter _____.

each new DNA double helix consists of one old DNA strand and one new DNA strand

After DNA replication is completed, _____.

labeled DNA ... DNA

After allowing phages grown with bacteria in a medium that contained 32P and 35S, Hershey and Chase used a centrifuge to separate the phage ghosts from the infected cell. They then examined the infected cells and found that they contained _____, which demonstrated that _____ is the phage's genetic material.

Descendants of the living cells are also phosphorescent.

After mixing a heat-killed, phosphorescent (light-emitting) strain of bacteria with a living, nonphosphorescent strain, you discover that some of the living cells are now phosphorescent. Which observation(s) would provide the best evidence that the ability to phosphoresce is a heritable trait?

daughter DNA

After replication is complete, the new DNAs, called __________, are identical to each other.

template

An old DNA strand is used as a _____ for the assembly of a new DNA strand.

Use the polymerase chain reaction

Archaeologists unearthed a human skull with a small dried fragment of the scalp still attached. They extracted a tiny amount of DNA from the scalp tissue. How could they obtain sufficient DNA for an analysis of the ancient human's genes?

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

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

replication fork

During DNA replication, an open section of DNA, in which a DNA polymerase can replicate DNA, is called a _______________.

Extension

During which step in the PCR cycle are nucleotides used?

Annealing

During which step in the PCR cycle do primers form bonds with a single-stranded template?

Amino acids (and thus proteins) also have nitrogen atoms; thus, the radioactivity would not distinguish between DNA and proteins.

For a science fair project, two students decided to repeat the Hershey and Chase experiment, with modifications. They decided to label the nitrogen of the DNA, rather than the phosphate. They reasoned that each nucleotide has only one phosphate and two to five nitrogens. Thus, labeling the nitrogens would provide a stronger signal than labeling the phosphates. Why won't this experiment work?

length

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

The transferred traits were heritable.

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?

35S

Hershey and Chase used _____ to radioactively label the T2 phage's proteins.

With an RNA virus radioactive RNA would have been in the final pellet.

Hershey and Chase used a DNA-based virus for their work. What would the results have been if they had used an RNA virus?

The cell's DNA couldn't be packed into its nucleus.

If a cell were unable to produce histone proteins, which of the following would be a likely effect?

Replication would not occur on either the leading or lagging strand.

In E. coli replication the enzyme primase is used to attach a 5 to 10 base ribonucleotide strand complementary to the parental DNA strand. The RNA strand serves as a starting point for the DNA polymerase that replicates the DNA. If a mutation occurred in the primase gene, which of the following would you expect?

No replication fork will be formed.

In E. coli, there is a mutation in a gene called dnaB that alters the helicase that normally acts at the origin. Which of the following would you expect as a result of this mutation?

thymine ... cytosine

In a DNA double helix an adenine of one strand always pairs with a(n) _____ of the complementary strand, and a guanine of one strand always pairs with a(n) _____ of the complementary strand.

A + C = G + T

In an analysis of the nucleotide composition of DNA, which of the following will be found?

negative ... positive

In gel electrophoresis DNA molecules migrate from _____ to _____ ends of the gel.

nuclease

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

be cut by the same restriction enzyme

In order to insert a human gene into a plasmid, both must _____

a restriction enzyme ... DNA ligase

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

Radioactively labeled phosphorus was present inside the infected bacteria.

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

B

In the accompanying image, a nucleotide is indicated by the letter _____.

DNA contains phosphorus, whereas protein does not.

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

They cannot repair thymine dimers.

Individuals with the disorder xeroderma pigmentosum are hypersensitive to sunlight. This occurs because their cells are impaired in what way?

ligase

Short segments of newly synthesized DNA are joined into a continuous strand by _____.

DNA

The radioactive isotope 32P labels the T2 phage's _____.

Yes, because the %A approximately equals the %T and the %G approximately equals the %C in both species.

Tables like the one shown here are useful for organizing sets of data representing a common set of values (in this case, percentages of A, G, C, and T) for a number of different samples (in this case, species). Does the distribution of bases in sea urchin DNA and salmon DNA follow Chargaff's rules?

replication forks and replication bubbles

The action of helicase creates _____.

the nucleoside triphosphates have the sugar deoxyribose; ATP has the sugar ribose.

The difference between ATP and the nucleoside triphosphates used during DNA synthesis is that

DNA polymerase

The enzyme that can replicate DNA is called _________.

helicase

The first step in the replication of DNA is catalyzed by _____.

a DNA double helix

The letter A indicates _____.

phosphate group

The letter A indicates a _____.

histones

The letter C indicates _____.

leading strand

The new DNA strand that grows continuously in the 5' to 3' direction is called the _____.

-ACGT

The sticky end of the DNA restriction fragment shown here will pair with a DNA restriction fragment with the sticky end _____.

RNA primer complementary to a preexisting DNA strand

The synthesis of a new strand begins with the synthesis of a(n) _____.

sticky ends

The unpaired nucleotides produced by the action of restriction enzymes are referred to as _____.

phage

This is an image of a _____.

nucleotide

This is an image of a(n) _____.

True

True or false? Single-stranded DNA molecules are said to be antiparallel when they are lined up next to each other but oriented in opposite directions.

false

True or false? The Taq enzyme is a type of DNA polymerase that allows researchers to separate the DNA strands during the annealing step of the PCR cycle without destroying the polymerase.

telomeres

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

DNA polymerase

What catalyzes DNA synthesis?

DNA ligase

What enzyme forms covalent bonds between restriction fragments?

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

What is meant by the description "antiparallel" regarding the strands that make up DNA?

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

What is the function of DNA polymerase III?

It untwists the double helix and separates the two DNA strands.

What is the function of helicase in DNA replication?

relieving strain in the DNA ahead of the replication fork

What is the function of topoisomerase?

III, II, IV, V, I

What is the most logical sequence of steps for splicing foreign DNA into a plasmid and inserting the plasmid into a bacterium? I. Transform bacteria with a recombinant DNA molecule. II. Cut the plasmid DNA using restriction enzymes. III. Extract plasmid DNA from bacterial cells. IV. Hydrogen-bond the plasmid DNA to nonplasmid DNA fragments. V. Use ligase to seal plasmid DNA to nonplasmid DNA.

A method to amplify a fragment of DNA.

What is the polymerase chain reaction (PCR)?

loops

What is this an image of?

supercoils

What is this an image of?

A

Where would RNA polymerase attach?

DNA polymerase III

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

Primase

Which of the following enzymes creates a primer for DNA polymerase?

Topoisomerase

Which of the following enzymes is important for relieving the tension in a helix as it unwinds during DNA synthesis?

The protein products of transgenes in GM food crops might lead to allergic reactions in human consumers. GM food crops might pass their new genes to close relatives in nearby wild areas

Which of the following is a concern expressed by opponents of the use of genetically modified (GM) food crops? Select all that apply. The protein products of transgenes in GM food crops might lead to allergic reactions in human consumers. GM food crops might pass their new genes to human consumers. GM food crops might pass their new genes to close relatives in nearby wild areas

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

Which of the following is true of DNA during interphase?

altering the nucleotide sequence of the DNA fragment without adding or removing nucleotides

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

Primers are short sequences that allow the initiation of DNA synthesis.

Which of the following statements about DNA synthesis is true?

They are formed on the lagging strand of DNA.

Which of the following statements about Okazaki fragments in E. coli is true?

Heterochromatin is highly condensed, whereas euchromatin is less compact.

Which of the following statements describes chromatin?

E

Which of these DNA molecules is the shortest?

sugar with two, and not three, oxygen atoms

You can tell that this is an image of a DNA nucleotide and not an RNA nucleotide because you see a _____.

Okazaki fragments

______________ are the short sections of DNA that are synthesized on the lagging strand of the replicating DNA.