MASTERING BIOLOGY-DNA REPLICATION
Cytosine makes up 38% of the nucleotides in a sample of DNA from an organism. Approximately what percentage of the nucleotides in this sample will be thymine?
12%
Hershey and Chase used ___ to radioactively label the T2 phage's proteins.
35S
In an analysis of the nucleotide composition of DNA, which of the following will be found?
A+C=G+T
Daughter DNA
After replication is complete, the new DNAs that are identical to each other
Which of the following investigators were responsible for the following discovery? Phage with labeled proteins or DNA was allowed to infect bacteria. It was shown that the DNA, but not the protein, entered the bacterial cells, and was therefore concluded to be the genetic material.
Alfred Hershey and Martha Chase
Single Strand Binding Protein
Binds after the replication fork; prevents H-bonds between bases
Topoisomerase
Binds ahead of the replication fork; Breaks covalent bonds in DNA backbone
Helicase
Binds at the replication fork; Breaks H-bonds between bases
The radioactive isotope 32P labels the T2 phage's
DNA
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, but 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.
What catalyzes DNA synthesis?
DNA polymerase
Which of the following removes the RNA nucleotides from the primer and adds equivalent DNA nucleotides to the 3' end of Okazaki fragments?
DNA polymerase 1
Which enzyme catalyzes the elongation of a DNA strand in the 5' to 3' direction?
DNA polymerase 3
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
After mixing a heat-killed, phosphorescent strain of bacteria with a living non-phosphorescent strain, you discover that some of the living cells are now phosphorescent. Which observations would provide the best evidence that the ability to fluoresce is a heritable trait?
Descendants of the living cells are also phosphorescent.
Replication fork
During DNA replication, an open section of DNA, in which a DNA polymerase can replicate DNA
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
Which of the following investigators was responsible for the following discovery? In DNA from any species, the amount of adenine equals the amount of thymine, and the amount of guanine equals the amount of cytosine.
Erwin Chargaff
The first step in the replication of DNA is catalyzed by
Helicase
Which of the following separates the DNA strands during replication?
Helicase
Who demonstrated that DNA is the genetic material of the T2 phage?
Hershey and Chase
In a nucleosome, the DNA is wrapped around
Histones
Why do histones bind tightly to DNA?
Histones are positively charged, and DNA is negatively charged
What kind of chemical bond is found between paired bases of the DNA double helix?
Hydrogen
What is the role of DNA ligase in the elongation of the lagging strand during DNA replication?
Join Okazaki fragments together
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.
Labeled DNA, DNA
Which of the following covalently connects segments of DNA?
Ligase
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 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
Which of the following synthesizes short segments of RNA?
Primase
Which of the following statements about DNA synthesis is true?
Primers are short sequences that allow the initiation of DNA synthesis
For a couple of decades, biologists knew the nucleus contained DNA and proteins. The prevailing opinion was that the genetic material was proteins, and not DNA. The reason for this belief was that proteins are more complex than DNA. What was the basis of this thinking?
Proteins have a greater variety of three-dimensional forms than does DNA.
Why does the DNA double helix have a uniform diameter?
Purines pair with pyrimidines
The synthesis of a new strand begins with the synthesis of a(n)
RNA primer complementary to a preexisting DNA strand
The action of helicase creates
Replication forks and replication bubbles
It became apparent to Watson and Crick after completion of their model that the DNA molecule could carry a vast amount of hereditary information in which of the following?
Sequence of bases
Okazaki fragments
Short sections of DNA that are synthesized on the lagging strand of the replicating DNA
Which of the following help to hold the DNA strand apart while they are being replicated?
Single-stranded binding proteins
An old DNA strand is used as a ___ for the assembly of a new DNA strand.
Template
What is meant by the description "antiparallel" regarding the strands that make up DNA?
The 5' to 3' direction of one strand runs counter to the 5' to 3' direction of the other strand
Charger's analysis of the relative base composition of DNA was significant because he was able to show that
The amount of A is always equivalent to T, and C to G
Which of the following can be determined directly from X-ray diffraction photographs of crystallized DNA?
The diameter of the helix
DNA polymerase
The enzyme that can replicate DNA
The leading and lagging strands 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.
Leading strand
The new DNA strand that grows continuously in the 5' to 3' direction
The difference between ATP and the nucleoside triphosphate used during DNA synthesis is that
The nucleoside triphosphates have the sugar deoxyribose; ATP has the sugar ribose
What determines the nucleotide sequence of the newly synthesized strand during DNA replication?
The nucleotide sequence of the template strand
When T2 phages infect bacteria and make more viruses in the presence of radioactive sulfur, what is the result?
The viral proteins will be radioactive
Which of the following statement about Okazaki fragments in E. Coli is true?
They are formed on the lagging strand of DNA.
Individuals with the disorder xeroderma pigmentosum are hypersensitive to sunlight. This occurs because their cells have which impaired ability?
They cannot repair thymine dimers.
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
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
What is the function of DNA polymerase 3?
To add nucleotides to the end of a growing DNA strand
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
Short segments of newly synthesized DNA are joined into a continuous strand by
ligase
