Chapter 13
An Okazaki fragment has which of the following arrangements? DNA polymerase I, DNA polymerase III primase, polymerase, ligase 3' RNA nucleotides, DNA nucleotides 5' 5' RNA nucleotides, DNA nucleotides 3'
5' RNA nucleotides, DNA nucleotides 3'
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? 3'-G C C T A G G-5' 5'-G C C U A G G-3' 5'-A C G U U A G G-3' 5'-A C G T T A G G-3'
5'-A C G U U A G G-3'
When must DNA replication occur during the cell cycle for each daughter cell to receive a complete copy of DNA? DNA replication must occur before mitosis. DNA replication must occur during mitosis DNA replication must occur during G2. DNA replication must occur during G1.
DNA replication must occur before mitosis.
Which conclusion about DNA replication is supported by the graph? DNA replication occurs during all phases of the cell cycle. DNA replication occurs only during the G1 phase of the cell cycle. DNA replication occurs only during the S phase of the cell cycle. DNA replication occurs randomly, and is unrelated to the cell cycle.
DNA replication occurs only during the S phase of the cell cycle.
What would happen if a cell divides before DNA replication is completed? Daughter cells would receive incomplete genetic information, but would regain lost information in the G1 phase. Daughter cells would receive incomplete genetic information, but would regain lost information in the S phase. Daughter cells would contain all genes of the parent cell, but would not function normally. Daughter cells would receive incomplete genetic information and never regain it, and they may not survive.
Daughter cells would receive incomplete genetic information and never regain it, and they may not survive.
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? DNA passed from the heat-killed strain to the living strain. Protein passed from the heat-killed strain to the living strain. The phosphorescence in the living strain is especially bright. Descendants of the living cells are also phosphorescent.
Descendants of the living cells are also phosphorescent.
DNA replication is said to be semiconservative. What does this mean? The old double helix is degraded, and half of its nucleotides are used in the construction of two new double helices Each new double helix consists of one old and one new strand. One of the two resulting double helices is made of two old strands, and the other is made of two new strands. Half of the old strand is degraded, and half is used as a template for the replication of a new strand. One strand of the new double helix is made of DNA, and the other strand is made of RNA.
Each new double helix consists of one old and one new strand.
How does DNA replication differ between eukaryotes and prokaryotes? The base-pairing rules are different between eukaryotes and prokaryotes. Only prokaryotes rely on enzymes such as DNA polymerase. Only eukaryotes rely on enzymes such as DNA polymerase. Eukaryotes use multiple replication forks to replicate a larger volume of DNA.
Eukaryotes use multiple replication forks to replicate a larger volume of DNA.
Which of the following statements describes chromatin? Heterochromatin is less compact, whereas euchromatin is less compact. Heterochromatin is highly condensed, whereas euchromatin is less compact.
Heterochromatin is highly condensed, whereas euchromatin is less compact.
Which of the following statements is true of histones? All histones are considered lipids Histone H1 is not present in the nucleosome bead; instead, it draws the nucleosomes together. Histone H1 is present in the nucleosome bead; instead, it draws the nucleosomes apart
Histone H1 is not present in the nucleosome bead; instead, it draws the nucleosomes together.
Why do histones bind tightly to DNA? Histones are negatively charged, and DNA is positively charged. Histones are positively charged, and DNA is negatively charged. Both histones and DNA are strongly hydrophobic. Histones are covalently linked to the DNA.
Histones are positively charged, and DNA is negatively charged.
Which of the following statements best describes the eukaryotic chromosome?ANSWER: It is composed of DNA alone. It consists of a single linear molecule of double-stranded DNA plus proteins. The number of genes on each chromosome is different in different cell types of an organism. The nucleosome is its most basic functional subunit.
It consists of a single linear molecule of double-stranded DNA plus proteins.
Which of the following statements describes the eukaryotic chromosome? It consists of a single linear molecule of double-stranded DNA plus proteins It consists of two linear molecule of single stranded DNA plus proteins It consists one linear molecule with no proteins
It consists of a single linear molecule of double-stranded DNA plus proteins.
Which of the following is true of DNA during interphase?ANSWER: It is in the form of highly condensed chromosomes and is unavailable for gene expression. It exists as chromatin and is less condensed than mitotic chromosomes. It is in the form of highly condensed chromosomes; it is called heterochromatin. It exists as chromatin; it is completely uncoiled and loose.It exists as chromatin and is unavailable for gene expression.
It exists as chromatin and is less condensed than mitotic chromosomes.
What is the role of DNA ligase in the elongation of the lagging strand during DNA replication? It catalyzes the lengthening of telomeres. It joins Okazaki fragments together. It synthesizes RNA nucleotides to make a primer. It stabilizes the unwound parental DNA.
It joins Okazaki fragments together.
In his transformation experiments, what did Griffith observe? Mutant mice were resistant to bacterial infections. Mixing a heat-killed pathogenic strain of bacteria with a living nonpathogenic strain can convert some of the living cells into the pathogenic form. Mixing a heat-killed nonpathogenic strain of bacteria with a living pathogenic strain makes the pathogenic strain nonpathogenic. Infecting mice with nonpathogenic strains of bacteria makes them resistant to pathogenic strains.
Mixing a heat-killed pathogenic strain of bacteria with a living nonpathogenic strain can convert some of the living cells into the pathogenic form.
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? Replication fork will form but with no usage Two replication forks will form No replication fork will be formed.
No replication fork will be formed.
Which of the following statements describe properties of the DNA molecule that are consistent with Chargaff's data? Select all of the answers that apply.
On a single strand, the four bases are repeated many times and in different combinations.
The Picture of the double-helix model of the DNA molecule resembles a twisted ladder. Choose all that apply. What makes up the rungs of the twisted ladder?
Paired Phosphate Group Paired Nitrogenous Bases Paired Sugars
What aspects of the structure of DNA are explained by this model? SELECT ALL THAT APPLY. Paired nucleotides are held together by covalent bonds (i.e. The 3'- carbon is linked with the 5'- carbon in the DNA via phosphodiester bonds). Adenine is paired with thymine, and guanine is paired with cytosine. Paired nucleotides are held together by hydrogen bonds of the nitrogenous bases. The two strands of DNA each have phosphate-sugar backbones The numbers of each nucleotide determine genetic information
Paired nucleotides are held together by covalent bonds (i.e. The 3'- carbon is linked with the 5'- carbon in the DNA via phosphodiester bonds). Adenine is paired with thymine, and guanine is paired with cytosine. Paired nucleotides are held together by hydrogen bonds of the nitrogenous bases. The two strands of DNA each have phosphate-sugar backbones
The enzyme DNA (Nuclease//Telomerase//polymerase) joins (amino acids// nucleotides//sugars) to synthesize a new (complementary//opposite//paired) DNA strand
Polymerase//nucleotides//complementary
Which of the following enzymes synthesizes short segments of RNA?ANSWER: helicase DNA polymerase III ligase DNA polymerase I primase
Primase
The diagram shows a model of DNA replication Which of the following labels should not be added to the model?
RNA polymerase
Which of the following events occur in DNA replication in prokaryotes? Regulatory proteins bind to all of the nucleotides on the DNA molecule Regulatory proteins do not bind, and instead carbohydrates bond on the DNA molecules Lipids bind to the DNA molecule only during prokaryotes DNA replication
Regulatory proteins bind to all of the nucleotides on the DNA molecule
Once the pattern found after one round of replication was observed, Meselson and Stahl could be confident of which of the following conclusions? Replication is semiconservative. Replication is not dispersive. Replication is neither dispersive nor conservative. Replication is not conservative.
Replication is not conservative.
What is meant by the description "antiparallel" regarding the two strands of nucleic acids that make up DNA? ANSWER: The twisting nature of DNA creates nonparallel strands. One strand contains only purines and the other contains only pyrimidines. The 5' to 3' direction of one strand runs counter to the 5' to 3' direction of the other strand. Base pairings create unequal spacing between the two DNA strands.
The 5' to 3' direction of one strand runs counter to the 5' to 3' direction of the other strand.
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?ANSWER: No proofreading will occur. The DNA will supercoil. The DNA strands at the origin of replication will separate, but replication will not progress .Replication will require a DNA template from another source.
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. Spindle fibers would not form during prophase. Expression of other genes would compensate for the lack of histones. DNA polymerase I would not function properly.
The cell's DNA couldn't be packed into its nucleus.
What can you conclude from the data in this table? How does the double-helix model of DNA explain Chargaff's rules of base pairing?
The data show that the percentage of adenine to thymine and guanine to cytosine is approximately equal in these samples of DNA. Watson and Crick realized that the double-helical shape of their model of the DNA molecule not only accounted for Franklin's x-ray diffraction pattern, but also for the two strands of DNA to run in opposite directions allowing the nitrogenous bases on both strands to pair properly (A and T; G and C) and interact to form hydrogen bonds in the center of the molecule.
What did Griffith conclude from these experiments? The S type bacteria produced a poison that made mice sick. The heat-killed S type bacteria transformed the harmless R type bacteria into disease-causing cells. The R type bacteria produced a poison that caused disease in mice. The heat-killed S type bacteria became harmless when injected into the mice along with the R type bacteria.
The heat-killed S type bacteria transformed the harmless R type bacteria into disease-causing cells.
Bacteria that do not take up any plasmids would grow on which media?
The nutrient broth only
Analysis of the data obtained shows that two students each have two fragments, two students each have three fragments, and two students each have one only. What does this demonstrate?
The two students who have two fragments have one restriction site in this region.
Studies of nucleosomes have shown that histones (except H1) exist in each nucleosome as two kinds of tetramers: one of 2 H2A molecules and 2 H2B molecules, and the other as 2 H3 and 2 H4 molecules. Which of the following is supported by this data?
The two types of tetramers associate to form an octamer.
In an experiment, DNA is allowed to replicate in an environment with all necessary enzymes, dATP, dCTP, dGTP, and radioactively labeled dTTP (3H thymidine). After several minutes, the DNA is switched to nonradioactive medium and is then viewed by electron microscopy and autoradiography. Figure 13.2 represents the results. It shows a replication bubble, and the dots represent radioactive material. Which of the following is the most likely interpretation of the results? There are three replication forks going in opposite directions There are one replication forks going in opposite directions There are two replication forks going in opposite directions
There are two replication forks going in opposite directions.
Individuals with the disorder xeroderma pigmentosum are hypersensitive to sunlight. This occurs because their cells are impaired in what way? They do not recombine homologous chromosomes during meiosis. They cannot repair thymine dimers. They cannot replicate DNA. They cannot exchange DNA with other cells.
They cannot repair thymine dimers.
Why might they be conducting such an experiment?
To find out which of the students has the allele
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?ANSWER: Use a nucleic acid probe. Use the polymerase chain reaction. Subject the specimen to amniocentesis. Subject the DNA to electrophoresis.
Use the polymerase chain reaction.
Frederic Griffith used the word transformation to describe the changes in bacteria that he observed. Which is the most useful definition of transformation? a permanent change in gene expression a temporary change in the function or activity of a cell a temporary change in the genetic composition of an organism a permanent change in the genetic composition of an organism
a permanent change in the genetic composition of an organism
Which enzyme was used to produce the molecule in Figure 13.3? ligase a restriction enzyme RNA polymerase DNA polymerase
a restriction enzyme
In DNA, thymine always pairs with (cytosine//guanine//adenine) and cytosine always pairs with (adenine//guanine//thymine) by forming (hydrogen bonds//covalent//ionic) across the complementary strands
adenine/guanine/hydrogen bonds
How is transformation in bacteria most accurately described? the creation of a strand of RNA from a DNA molecule the infection of cells by a phage DNA molecule assimilation of external DNA into a cell the type of semiconservative replication shown by DNA
assimilation of external DNA into a cell
During DNA replication, which of the following enzymes separates the DNA strands during replication? DNA polymerase III helicase primase DNA polymerase I
helicase
The table shows data Chargaff collected on DNA nitrogenous bases in five organisms.Which statement did Chargaff conclude based on these data? Note that a letter in brackets, such as [A] or [C], refers to the concentration of one of the nitrogenous bases.
in DNA molecules, [A] = [T], and [C ] = [G]
Bacteria that contain the plasmid, but not the eukaryotic gene, would grow
in all four types of broth
Bacteria containing a plasmid into which the eukaryotic gene has integrated would grow
in the ampicillin broth and the nutrient broth.
During DNA replication, which of the following enzymes covalently connects segments of DNA? helicase DNA polymerase I primase ligase
ligase
In nucleotide excision repair, damaged DNA is excised by what enzyme(s)?ANSWER :DNA polymerases ligase helicase nuclease primase
nuclease
In which order do the necessary enzymes act to repair a thymine dimer by nucleotide excision repair? DNA ligase, nuclease, helicase DNA polymerase, RNA polymerase, DNA ligase helicase, DNA polymerase, DNA ligase nuclease, DNA polymerase, DNA ligase
nuclease, DNA polymerase, DNA ligase
Which of the following represents the order of increasingly higher levels of organization of chromatin?
nucleosome, 30-nm chromatin fiber, looped domain
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 high-density and one low-density band one intermediate-density band one high-density and one intermediate-density band one low-density and one intermediate-density band
one low-density and one intermediate-density band
Telomeres are located near the tips of eukaryotic DNA. During DNA replication, what is the role of enzymes called telomerases? removing damaged telomeres from the DNA molecules attaching telomeres onto newly-synthesized DNA molecules preventing telomeres from migrating elsewhere in a DNA molecule preventing loss or damage of genes near telomeres
preventing loss or damage of genes near telomeres
Which of the following enzymes synthesizes short segments of RNA? primase DNA polymerase I DNA polymerase III ligase
primase
Polytene chromosomes of Drosophila salivary glands each consist of multiple identical DNA strands that are aligned in parallel arrays. How could these arise? Replication and separation correctly replication without separation
replication without separation
Which of the following help(s) to hold the DNA strands apart while they are being replicated? primase ligase nuclease single-strand binding proteins
single-strand binding proteins
In his work with pneumonia-causing bacteria and mice, Griffith found that the protein coat from pathogenic cells was able to transform nonpathogenic cells. heat-killed pathogenic cells caused pneumonia. some substance from pathogenic cells was transferred to nonpathogenic cells, making them pathogenic. the polysaccharide coat of bacteria caused pneumonia.
some substance from pathogenic cells was transferred to nonpathogenic cells, making them pathogenic.
In a linear eukaryotic chromatin sample, which of the following strands is looped into domains by scaffolding? 10 nm chromatin 30 nm chromatin fiber 300 nm chromatin
the 30-nm chromatin fiber
Given the damage caused by UV radiation, the kind of gene affected in those with XP is one whose product is involved with
the ability to excise single-strand damage and replace it.
Which of the following characteristics can be determined directly from X-ray diffraction photographs of crystallized DNA?ANSWER: the frequency of A versus T nucleotides the rate of replication the diameter of the helix the sequence of nucleotides
the diameter of the helix
The difference between ATP and the nucleoside triphosphates used during DNA synthesis is that the nucleoside triphosphates have two phosphate groups; ATP has three phosphate groups. the nucleoside triphosphates have the sugar deoxyribose; ATP has the sugar ribose. ATP is found only in human cells; the nucleoside triphosphates are found in all animal and plant cells. ATP contains three high-energy bonds; the nucleoside triphosphates have two.
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 the nucleoside triphosphates have two phosphate groups; ATP has three phosphate groups. the nucleoside triphosphates have three phosphate groups; ATP also has three neither has phosphate groups
the nucleoside triphosphates have two phosphate groups; ATP has three phosphate groups.
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 phosphate-sugar backbones complementary pairing of bases different five-carbon sugars
the sequence of bases
In the Hershey-Chase experiment, the components of bacteriophages were labeled with radioactive isotopes of sulfur and phosphorus. What was the Hershey-Chase experiment designed to determine? whether or not bacteriophages can infect bacteria whether DNA or RNA is the genetic material of bacteriophages whether cells use DNA or proteins to store genetic information whether or not viruses satisfy the criteria for life
whether cells use DNA or proteins to store genetic information
In the late 1950s, Meselson and Stahl grew bacteria in a medium containing "heavy" nitrogen (15N) and then transferred them to a medium containing 14N. Which of the results in Figure 13.1 would be expected after one round of DNA replication in the presence of 14N? E D A C
D
In trying to determine whether DNA or protein is the genetic material, Hershey and Chase made use of which of the following facts? ANSWER: DNA contains phosphorus, whereas protein does not. DNA contains nitrogen, whereas protein does not. DNA contains purines, whereas protein includes pyrimidines. RNA includes ribose, whereas DNA includes deoxyribose sugars.DNA contains sulfur, whereas protein does not.
DNA contains phosphorus, whereas protein does not.
Suppose you are provided with an actively dividing culture of E. coli bacteria to which radioactive thymine has been added. What would happen if a cell replicates once in the presence of this radioactive base?
DNA in both daughter cells would be radioactive.
Chargaff's rules of base pairing are explained by which structural feature of DNA? Each strand of DNA contains a phosphate and sugar backbone. The nucleotides of DNA may appear in a wide variety of sequences. DNA is double stranded, and covalent bonds between identical nucleotides hold the strands together. DNA is double stranded, and hydrogen bonds between base pairs hold the strands together.
DNA is double stranded, and hydrogen bonds between base pairs hold the strands together.
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? ANSWER: DNA ligase primase DNA polymerase Okazaki fragments
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 III helicase primase DNA polymerase I
DNA polymerase I
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?ANSWER: helicase DNA polymerase III ligase DNA polymerase I primase
DNA polymerase I
Which enzyme catalyzes the elongation of a DNA strand in the 5' → 3' direction? topoisomerase DNA polymerase III helicase primase
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. Helicases and single-strand binding proteins work at the 5' end. The origins of replication occur only at the 5' end. DNA ligase works only in the 3' → 5' direction.
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 begins adding nucleotides at the 5' end of the template. Okazaki fragments prevent elongation in the 3' to 5' direction. replication must progress toward the replication fork. DNA pOkazaki fragments prevent elongation in the 3' to 5' direction. replication must progress toward the replication fork. DNA polymerase can only add nucleotides to the free 3' end.
DNA polymerase can only add nucleotides to the free 3' end.
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? There is no radioactive isotope of nitrogen. Avery et al. have already concluded that this experiment showed inconclusive results. Although there are more nitrogens in a nucleotide, labeled phosphates actually have 16 extra neutrons; therefore, they are more radioactive. Amino acids (and thus proteins) also have nitrogen atoms; thus, the radioactivity would not distinguish between DNA and proteins.
Amino acids (and thus proteins) also have nitrogen atoms; thus, the radioactivity would not distinguish between DNA and proteins.
A space probe returns with a culture of a microorganism found on a distant planet. Analysis shows that it is a carbon-based life-form that has DNA. You grow the cells in 15N medium for several generations and then transfer them to 14N medium. Which pattern in Figure 13.1 would you expect after one round of DNA replication if the DNA was replicated in a conservative manner? D E A B
B
Griffith investigated how certain types of bacteria produce pneumonia in mice. The diagram outlines his experiments. How did the results of the experiment show the process of transformation?
Based on the results, Griffith was able to conclude that a hertiable substance transforms harmless bacteria into harmful bacteria. He reasoned that this was true because it was evident that one type of bacteria (the harmless form) has been permanently changed into the disease-causing form
How does the double-helical structure of DNA explain how the molecules can be copied or replicated? Because of base pairing, each strand has all the information to serve as a template for the other strand. Each strand receives the information from the DNA polymerase attached to the replication fork. The nitrogenous bases on one strand are copied to the other strand. The nitrogenous bases line up on each strand and are attached to each other.
Because of base pairing, each strand has all the information to serve as a template for the other strand.
A scientist uses radioactive isotopes to label a double-stranded molecule of DNA. Then the DNA undergoes replication in a non-radioactive medium. Where are the two original radioactive strands of DNA? Both strands are intact, and both are part of the same molecule of DNA. Both strands are intact, and each is part of a different molecule of DNA. One strand is intact, while the other strand is broken apart and distributed among the new DNA molecules. Both strands are broken apart, and their pieces are distributed among the new DNA molecules.
Both strands are intact, and each is part of a different molecule of DNA.