chapter 14
The purpose of the Hershey Chase experiments was to determine whether a bacteriophage injected ______ or ______ into bacteria.
protein and DNA
The results of the Hershey and Chase experiments suggested that DNA was the genetic material because
radioactive bacteriophage DNA was found in the cytoplasm of bacterial cells
A is the partial opening of a DNA helix to form two single strands.
replication fork
The DNA controlled by an origin is called a
replicon
The DNA controlled by an origin is called a .
replicon
DNA replication is said to be
semi-conservative
The partial opening of a DNA helix to form two single strands is called
the replication fork
Chargaff's experiments showed that the amount of adenine in a sample was always the same as the amount of
thymine
Based on his experiments with the bacterium S. pneumoniae, Griffith concluded that the genetic information for virulence was transferred from dead, virulent cells to live, nonvirulent cells, a process he called ______.
transformation
Griffith performed experiments, which demonstrated
transformation in bacteria.
Agents that damage DNA can lead to mutations.
true
All cells that have been examined show multiple pathways for repairing damaged DNA and for reversing errors that occur during replication.
true
Although most mutations are harmful, some may be beneficial.
true
During Griffith's experiments, a nonvirulent form of S. pneumoniae was transformed into a virulent form.
true
During bacterial transformation, one or more traits of a cell are altered due to the uptake of DNA from the surrounding environment.
true
Which of these are used in RNA?
uracil guanine cytosine adenine
Which of the following DNA sequences is complementary to 5' TAGAC 3'?
5' GTCTA 3'
A segment of DNA has the sequence 5'-ATGCCC-3'. The complementary sequence would be
5'-GGGCAT-3'
Which enzymes did Avery, MacLeod, and McCarty use in order to identify the genetic material?
RNA digesting enzymes DNA digesting enzymes protein digesting enzymes
DNA replication in bacteria begins at
a single origin and proceeds in both directions
Genes, which contain trait specifying information, are located on
chromosomes
An ______ cuts DNA internally and an ______ cuts at the ends of DNA.
endonuclease; exonuclease
During DNA replication, the strand is synthesized continuously while the strand is synthesized as small fragments that are connected to each other to form a continuous strand.
leading, lagging
As the lagging strand is being synthesized, adjacent Okazaki fragments are joined by the enzyme DNA .
ligase
During semiconservative DNA replication
one of the strands in each new double helix comes from the original molecule, and one is newly synthesized
If 35S was found in progeny phages rather than 32P, Hershey and Chase would have concluded that
phage protein enters the host cell.
The correct structure of DNA monomers can be presented as
phosphate-sugar-base.
What protein cuts the damaged DNA strand?
UvrC
Which protein has a helicase function?
UvrD
The major significance of the Hershey and Chase's experiments is that they
determined that DNA is the genetic material
Repeating sugar and phosphate units in a single DNA strand make up the
phosphodiester backbone.
DNA replication that leads to the production of double helices with one parental strand and one newly synthesized strand is consistent with
semiconservative replication
DNA polymerases cannot replicate
the 3' end of linear chromosomes.
Many DNA polymerases have 3'-to-5'exonuclease activity that allows "proofreading" and replacement of incorrect bases.
true
DNA replication is said to be
semi-conservative.
Franklin determined that the structure of DNA was helical based on
x-ray diffraction analysis
How many hydrogen bonds are formed between adenine and thymine in the double DNA helix?
2
X-ray diffraction was used to determine that the diameter of a DNA molecule is
2 nm
Which of the following statements about the repair mechanism involving photolyase is TRUE?
Photolyase is oxidized and the damaged DNA is reduced.
Which of these is not one of the three phases of DNA replication?
extension
The primary purpose of the Meselson and Stahl experiments was to determine
how DNA replicates.
In order to determine the density of DNA strands, Meselson and Stahl used this technique so that DNA fragments would migrate to the area in the gradient where they had the same density.
A cesium chloride gradient
What enzyme is responsible for repairing thymine dimers using the energy of light?
DNA photolyase
RNA primers are removed by the action of the enzyme
DNA pol I.
Which enzyme covalently links nucleotides together?
DNA polymerase
Which of the following synthesizes the new DNA strand?
DNA polymerase
Viruses that infect bacteria are known as
bacteriophages
How does UV light and other ionizing radiations damage DNA molecules?
creating thymine dimers between adjacent thymines in the DNA chain.
E. coli polymerases I, II, and III have 3' to 5' activity, which provides them with a proofreading function, i.e. they can remove a mispaired base.
exonuclease
"Proofreading" effectively eliminates all errors during DNA replication.
false
Any agent that decreases the number of mutations below background levels is called a mutagen.
false
Avery, MacLeod, and McCarty were the first scientists to describe the process of bacterial transformation.
false
Griffith determined that DNA is the substance responsible for bacterial transformation.
false
During their experiments, Avery, MacLeod, and McCarty discovered that the removal of nearly all protein from their preparation destroyed its transforming activity.
fasle
Regarding Meselson and Stahl's experiment, the primary difference between the proposed models of DNA replication was related to
how the parental strands were incorporated into the daughter strands
What kind of bond do thimine dimers weaken?
hydrogen bond
The primary reason the bacteriophage was an ideal model system for the Hershey Chase experiments was
it is made of only protein and DNA.
The enzyme DNA synthesizes the RNA primers required by DNA polymerases during replication.
primase
The model organism used by Meselson and Stahl was
Escherichia coli.
Which of the following statements about the DNA double helix is TRUE?
Complementary base pairing across the double helix allows information to be transferred via RNA transcription and DNA replication.
Avery, MacLeod, and McCarty determined that the substance responsible for changing live, nonvirulent bacteria into live, virulent bacteria was _____.
DNA
What part of the phage entered the bacterial cell following infection?
DNA
Which of the following DNA molecules is the most stable?
GCGTGCAC CGCACGTG
The experiments with radioactively labeled phage that showed that DNA was the genetic material were performed by
Hershey and Chase
Which of the following best describes the function of telomerase at the telomere?
It adds new DNA to the longer strand of the telomere overhang.
What might result for a eukaryotic organism that lacked functional telomerase?
It would have shorter chromosomes with every round of mitosis, leading to abnormal cells.
Which of these is not required for DNA replication?
NADPH
Which of the following is required to replicate the lagging strand of DNA?
Okazaki fragments, primase and DNA ligase
In which of the following chromosomal entities are an individual's traits specified?
genes
Indicate the 4 nitrogenous bases used in DNA.
guanine cytosine adenine thymine
The enzyme uses ATP to unwind the DNA template.
helicase
When the double stranded DNA helix is unwound, two single strands of DNA are formed. These strands have to be stabilized because their hydrophobic bases are exposed to water. The proteins that stabilize the two single strands are called
single-strand binding proteins
The DNA backbone is composed of (choose all that apply)
phosphate groups. sugars
Which of the following is a characteristic of double-stranded DNA?
2 nanometers in width, 10 base pairs per turn and 0.34 nanometers per basepair
Arrange the following proteins in the proper order in which they participate in DNA replication. 1 = Primase 2 = Helicase 3 = Single-strand binding proteins 4 = DNA polymerase I
2, 3, 1, 4
Evaluate the statements below and determine which is the best explanation for why bacteria don't use telomerase.
Bacteria have circular chromosomes that do not shorten.
How is bacterial DNA replication different from eukaryotic DNA replication?
Bacterial DNA replication moves out from the origin of replication in two directions, while eukaryotic DNA replication moves out from the origin of replication in only one direction.
How is bacterial DNA replication similar to eukaryotic DNA replication?
Both bacterial and eukaryotic DNA replication is semiconservative.
In their experiments, Avery, MacLeod, and McCarty isolated a substance, which had a transforming activity. Which of the following destroyed that substance's ability to transform bacterial cells?
DNA-digesting enzymes
Evaluate the following statements and determine which is the most likely explanation for how the methylation of a guanine might induce mutations in the DNA?
The guanine will not properly hydrogen bond with cytosine across the double helix.
Bacterial DNA is typically replicated as
a single replicon
Features of the Watson and Crick model include
a sugar phosphate backbone a helical structure a double stranded structure
A heavy isotope of nitrogen was used in the Meselson-Stahl experiment so that
different DNA molecules could be separated via ultracentrifugation.
Franklin used x-ray to suggest that DNA has a helical structure.
diffraction
Hershey and Chase used radioactively labeled protein and DNA to demonstrate that the genetic material of ______ is DNA.
phages
Adjacent nucleotides in the same DNA strand are held together by covalent bonds known as bonds.
phosphodiester
In DNA, consecutive nucleotides are linked via bonds, which are made between the 5' phosphate of one nucleotide and the 3' group of another nucleotide.
phosphodiester, hydroxyl
The enzyme DNA covalently links nucleotides to synthesize new DNA strands together during DNA replication.
polymerase
Which of the following data were available to Watson and Crick when they were trying to determine the structure of DNA? Check all that apply.
-DNA is composed of 3 basic components: five-carbon sugars, phosphate groups, and 4 different nitrogenous bases. -In DNA, the proportion of adenine always equals that of thymine, and the proportion of guanine always equals that of cytosine. -X-ray diffraction patterns indicate that the DNA molecule has the shape of a helix. -In DNA, the predominant tautomeric forms of the nitrogenous bases contain keto and amino groups. -DNA always has an equal proportion of purines and pyrimidines. -The DNA molecule contains a backbone of repeating sugar and phosphate units joined by phosphodiester bonds. -The replication of DNA is semiconservative. -During DNA replication, synthesis of the leading strand is continuous and synthesis of the lagging strand is discontinuous.
Guanine forms hydrogen bonds with cytosine.
3
How many hydrogen bonds form between cytosine and guanine in the DNA double helix?
3
Which model for DNA replication suggests that both strands of the double helix remain intact and the new DNA double helix consists of two new DNA strands?
The conservative model
A mutation has occurred that has made UvrC non-functional. What result will this have on damaged DNA?
The damaged DNA will be recognized, but no cut will be made to the damaged segment.
A mutation has occurred that prevents UvrA and UvrB from forming a complex. What result will this have on damaged DNA?
The damaged DNA will not be recognized.
The DNA structure proposed by Watson and Crick involves
a sugar phosphate backbone a helical structure two grooves (major and minor)
Telomerase is unique because it contains
an RNA molecule
Nucleotides contain a sugar, a phosphate, and a nitrogenous .
base
This model of DNA replication suggests that newly synthesized strands of DNA have mixtures of parental and newly synthesized strands of DNA:
dispersive
The level of DNA structure that resembles a spiral staircase is the
double helix
The genetic material in bacteria is
double-stranded DNA.
Cells cannot escape exposure to mutagens, but they have evolved systems that enable them to repair all of the damage.
false
Error correcting mechanisms during DNA replication cause cells to accumulate errors at a higher rate, which leads to higher levels of deleterious or lethal mutations.
false
Select all of the following that are components of a nucleotide.
sugar phosphate group nitrogenous base
Chargaff's rule indicates that the amount of A in a sample is equal to the amount of and the amount of C in a sample is equal to the amount of .
t g
List the three phases of DNA replication:
termination elongation initiation
Griffith's experiments were important because they showed
that the genetic material could be passed from one cell to another
In addition to errors that occur during DNA replication, cells are constantly exposed to agents that can damage DNA, such as UV light, X-rays, and chemicals in the environment.
true
