AP BIO CHP 13
The enzyme that can replicate DNA is called
DNA polymerase
Select the most accurate statement describing DNA replication complexes.
DNA replication complexes are grouped into factories, which are anchored to the nuclear matrix.
Who conducted the X-ray diffraction studies that were key to the discovery of the structure of DNA?
Franklin
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.
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.
Which enzyme was used to produce the molecule in the figure?
a restriction enzyme
In order to insert a human gene into a plasmid, both must ___
be cut by the same restriction enzyme
Which of the following functions in the regulation of gene expression?
euchromatin
During DNA replication, which of the following enzymes separates the DNA strands during replication?
helicase
In a nucleosome, the DNA is wrapped around ________
histones
Gel electrophoresis separates DNA fragments on the basis of what characteristic?
length
E. coli cells grown on 15N medium are transferred to 14N medium and allowed to grow for two more generations (two rounds of DNA replication). DNA extracted from these cells is centrifuged. What density distribution of DNA would you expect in this experiment?
one low-density and one intermediate-density band
Which part of a deoxynucleoside triphosphate (dNTP) molecule provides the energy for DNA synthesis?
phosphate groups
Which of the following enzymes creates a primer for DNA polymerase?
primase
What is the function of topoisomerase?
relieving strain in the DNA ahead of the replication fork
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.
The difference between ATP and the nucleoside triphosphates used during DNA synthesis is that
the nucleoside triphosphates have the sugar deoxyribose; ATP has the sugar ribose
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
In contrast to the leading strand, the lagging strand is synthesized as a series of segments called Okazaki fragments. The diagram below illustrates a lagging strand with the replication fork off-screen to the right. Fragment A is the most recently synthesized Okazaki fragment. Fragment B will be synthesized next in the space between primers A and B.
1 Pol III binds to 3' end of primer B2 Pol III moves 5' to 3'3 Pol I Binds to 5' end primer A4 Pol I replaces primer A with DNA5 DNA ligase links fragments A and B
In a nucleotide, the nitrogenous base is attached to the sugar's _____ carbon and the phosphate group is attached to the sugar's _____ carbon.
1....5
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
What enzyme forms covalent bonds between restriction fragments?
DNA ligase
What catalyzes DNA synthesis?
DNA polymerase
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.
What is the most logical sequence of steps for splicing foreign DNA into a plasmid and inserting the plasmid into a bacterium?
Extract plasmid DNA from bacterial cells. Cut the plasmid DNA using restriction enzymes. Hydrogen-bond the plasmid DNA to nonplasmid DNA fragments. Use ligase to seal plasmid DNA to nonplasmid DNA. Transform bacteria with a recombinant DNA molecule.
Which of the following sequences in double-stranded DNA is most likely to be recognized as a cutting site for a restriction enzyme?
GGCC CCGG
Which of the following statements correctly describes chromatin?
Heterochromatin is highly condensed, whereas euchromatin is less compact.
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?
The DNA strands at the origin of replication will separate, but replication will not progress.
If a cell were unable to produce histone proteins, which of the following would be a likely effect?
The cell's DNA couldn't be packed into its nucleus.
Which of the following is a concern expressed by opponents of the use of genetically modified (GM) food crops?
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 statements about Okazaki fragments in E. coli is true?
They are formed on the lagging strand of DNA.
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?
Use the polymerase chain reaction.
dna and rna both
contain pentose sugars
The elongation of the leading strand during DNA synthesis ________
depends on the action of DNA polymerase
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
After DNA replication is completed, ___
each new DNA double helix consists of one old DNA strand and one new DNA strand
After DNA replication is completed, ____
each new DNA double helix consists of one old DNA strand and one new DNA strand
Unwinding the DNAAs DNA replication continues and the replication bubble expands, the parental double helix is unwound and separated into its two component strands. This unwinding and separating of the DNA requires three different types of proteins: helicase, topoisomerase, and single-strand binding proteins.
helicase: binds at the replication fork, breaks H-bonds between basestopoisomerase: binds ahead of the replication fork, breaks covalent bonds in DNA backbonesingle-strand binding protein: binds after the replication fork, prevents H-bonds between bases
A eukaryotic gene has "sticky ends" produced by the restriction endonuclease EcoRI. The gene is added to a mixture containing EcoRI and a bacterial plasmid that carries two genes conferring resistance to ampicillin and tetracycline. The plasmid has one recognition site for EcoRI located in the tetracycline resistance gene. This mixture is incubated for several hours, exposed to DNA ligase, and then added to bacteria growing in nutrient broth. The bacteria are allowed to grow overnight and are streaked on a plate using a technique that produces isolated colonies that are clones of the original. Samples of these colonies are then grown in four different media: nutrient broth plus ampicillin, nutrient broth plus tetracycline, nutrient broth plus ampicillin and tetracycline, and nutrient broth without antibiotics.Bacteria that contain the plasmid, but not the eukaryotic gene, would grow
in all four types of broth
The new DNA strand that grows continuously in the 5' to 3' direction is called the _________
leading strand
As the two parental (template) DNA strands separate at a replication fork, each of the strands is separately copied by a DNA polymerase III (orange), producing two new daughter strands (light blue), each complementary to its respective parental strand. Because the two parental strands are antiparallel, the two new strands (the leading and lagging strands) cannot be synthesized in the same way.
leading strand: daughter strand elongates toward replication fork, only one primer needed, made continuouslylagging strand: made in segments, daughter strand elongates away from replication fork, multiple primers neededboth strands: synthesized 5' to 3'
During DNA replication, which of the following enzymes covalently connects segments of DNA?
ligase
Short segments of newly synthesized DNA are joined into a continuous strand by _____
ligase
In nucleotide excision repair, damaged DNA is excised by what enzyme(s)?
nuclease
The spontaneous loss of amino groups from adenine in DNA results in hypoxanthine, an uncommon base, opposite thymine. What combination of proteins could repair such damage?
nuclease, DNA polymerase, DNA ligase
Which of the following enzymes synthesizes short segments of RNA?
primase
Which of the following help(s) to hold the DNA strands apart while they are being replicated?
single-strand binding proteins
What is the function of DNA polymerase III?
to add nucleotides to the 3' end of a growing DNA strand
At a specific area of a chromosome, the following sequence of nucleotides is present where the chain opens to form a replication fork:3' C C T A G G C T G C A A T C C 5'An RNA primer is formed starting at the underlined T (T) of the template. Which of the following represents the primer sequence?
5' A C G U U A G G 3'
An Okazaki fragment has which of the following arrangements?
5' RNA nucleotides, DNA nucleotides 3'
Nucleic acids are assembled in the _____ direction.
5...3
Deoxyribose binds to what part of the model
A polynucleotide contains a sugar/phosphate backbone, where the sugar of one nucleotide binds to the phosphate of the next, and so on.
Meselson and Stahl cultured E. coli for several generations in a medium with a heavy isotope of nitrogen, 15N. They transferred the bacteria to a medium with a light isotope of nitrogen, 14 N. After two rounds of DNA replication, half the DNA molecules were light (both strands had 14N) and half were hybrids (15N-14N). What did the researchers conclude from these results?
DNA replication is semiconservative.
Nucleotides are added to a growing DNA strand as nucleoside triphosphates. What is the significance of this fact?
Hydrolysis of the two phosphate groups (P-Pi) and DNA polymerization are a coupled exergonic reaction
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.
Which of the following statements about DNA synthesis is true?
Primers are short sequences that allow the initiation of DNA synthesis.
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.
The synthesis of a new strand begins with the synthesis of a(n) ____
RNA primer complementary to a preexisting DNA strand
A researcher is preparing to insert a human gene of interest into a bacterial plasmid in order to clone the human gene. She has genetically engineered the plasmid to carry a gene amp R , which confers resistance to the antibiotic ampicillin. She will include ampicillin in the plating medium when she grows the recombinant bacteria. Why has she engineered the plasmid to include an antibiotic resistance gene? Choose the best answer.
Recombinant bacteria that have taken up the plasmid can be recognized because they are able to survive in the presence of ampicillin.
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?
Replication would not occur on either the leading or lagging strand
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
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
Part complete Cold case detectives are investigating a homicide that took place 30 years ago. In reexamining the evidence, they find a tiny spot of blood on the victim's clothing that was likely left by the murderer. The DNA in the blood has partially degraded over time. What technique(s) would the blood lab technicians use in their examination of this tiny, degraded blood sample?
They would use PCR to amplify the DNA
Hershey and Chase used a DNA-based virus for their work. What would the results have been if they had used an RNA virus?
With an RNA virus radioactive RNA would have been in the final pellet
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
After replication is complete, the new DNAs, called ______, are identical to each othe
daughter DNA
The first step in the replication of DNA is catalyzed by ____
helicase
Which of the following is an example of "recombinant DNA technology"?
introducing a human gene into a bacterial plasmid
Which of the following lists of structures correctly represents the order of increasingly higher levels of organization of chromatin?
nucleosome, 30-nm chromatin fiber, looped domain
What process repairs damage to a preexisting double helix?
nucleotide excision repair
_____ are the short sections of DNA that are synthesized on the lagging strand of the replicating DNA.
okazaki fragments
Histones
protein molecules around which DNA is tightly coiled in chromatin
During DNA replication, an open section of DNA, in which a DNA polymerase can replicate DNA, is called a
replication fork
The action of helicase creates ____
replication forks and replication bubbles
Polytene chromosomes of Drosophila salivary glands each consist of multiple identical DNA strands that are aligned in parallel structures. How could these arise?
replication without separation
In his work with pneumonia-causing bacteria and mice, Griffith found that _________
some substance from pathogenic cells was transferred to nonpathogenic cells, making them pathogenic
What are the repetitive DNA sequences present at the ends of eukaryotic chromosomes called?
telomeres
An old DNA strand is used as a _____ for the assembly of a new DNA strand.
template
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.
thymine ... cytosine
Which of the following enzymes is important for relieving the tension in a helix as it unwinds during DNA synthesis?
topoisomerase
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.
true
What are chromosomes made of?
DNA and protein
A student isolates, purifies, and combines in a test tube a variety of molecules needed for DNA replication. After adding some DNA to the mixture, replication occurs, but each DNA molecule consists of a normal strand paired with numerous segments of DNA a few hundred nucleotides long. What has the student probably LEFT OUT of the mixture?
DNA ligase
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 1
Why is the new DNA strand complementary to the 3' to 5' strands assembled in short segments?
DNA polymerase can assemble DNA only in the 5' to 3' direction
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.
The lagging strand is characterized by a series of short segments of DNA (Okazaki fragments) that will be joined together to form a finished lagging strand. The experiments that led to the discovery of Okazaki fragments gave evidence for which of the following ideas?
DNA polymerase is a directional enzyme that synthesizes leading and lagging strands during replication.
The diagram below shows a replication bubble with synthesis of the leading and lagging strands on both sides of the bubble. The parental DNA is shown in dark blue, the newly synthesized DNA is light blue, and the RNA primers associated with each strand are red. The origin of replication is indicated by the black dots on the parental strands.
As soon as the replication bubble opens and the replication machinery is assembled at the two replication forks, the two primers for the leading strands (primers a and h) are produced. The production of the first primers on the lagging strands (those closest to the origin of replication, b and g) is delayed slightly because the replication forks must open up further to expose the template DNA for the lagging strands. After completion of the first segments of the lagging strands, additional template DNA must be exposed before the second primers (c and f) can be produced. And after completion of the second segments, additional template DNA must be exposed before the third primers (d and e) can be produced. In summary, because of the way the replication bubble expands, the lagging strand primers near the origin of replication were produced before the primers near the replication forks.
