Assignment 5
Why is DNA replication essential for a cell?
An organism must copy its DNA to pass genetic information to its offspring.
Bacteria typically contain multiple chromosomes. True False
False
What is the function of topoisomerase?
Relieving strain in the DNA ahead of the replication fork.
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.
What determines the nucleotide sequence of the newly synthesized strand during DNA replication?
The nucleotide sequence of the template strand.
The Ames test involves exposure of a histidine requiring strain of Salmonella typhimurium. After the test, mutants grow on a medium that is histidine-free. These mutants are an example of pyrimidine dimer formation point mutation site-direct mutagenesis back mutation
back mutation
What kind of chemical bond is found between paired bases of the DNA double helix? hydrogen covalent phosphate ionic sulfhydryl
hydrogen
All of the following are associated with nucleic acid structure EXCEPT uracil. ribose. phosphate. ionic bonds. hydrogen bonds.
ionic bonds
The sequence of the DNA "backbone is
phosphate-sugar-phosphate-sugar
Which of the following synthesizes short segments of RNA? DNA polymerase III ligase DNA polymerase I primase helicase
primase
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? side groups of nitrogenous bases sequence of bases different five-carbon sugars phosphate-sugar backbones complementary pairing of bases
sequence of bases
What is the function of DNA polymerase III?
to add nucleotides to the end of a growing DNA strand
Which of the following characteristics of a chromosome would identify it as a prokaryotic chromosome rather than a eukaryotic chromosome? It is a circular molecule. It contains double-stranded DNA. It contains histones. It contains A, C, G, and T.
It is a circular molecule.
DNA is synthesized through a process known as _____.
Semiconservative replication
Which of the following sets of materials are required by both eukaryotes and prokaryotes for replication? nucleosome loosening, 4 dNTPs, 4 rNTPs topoisomerases, telomerase, polymerases ligase, primers, nucleases double-stranded DNA, 4 kinds of dNTPs, primers, origins G-C rich regions, polymerases, chromosome nicks
double-stranded DNA, 4 kinds of dNTPs, primers, origins
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.
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%
In DNA replication, which nucleotides would pair up with the following nucleotides? A C G
A ---- T C ---- G G ---- C
Which enzyme breaks the hydrogen bonds during replication? Replication fork Stabilizing proteins DNA helicase ATP
DNA Helicase
Which enzyme catalyzes the elongation of a DNA strand in the 5' →♦ 3' direction? DNA ligase DNA polymerase III topoisomerase primase helicase
DNA Polymerase III
What characteristic of DNA allows two connected DNA polymerases to synthesize both the leading and lagging strands? DNA is flexible. DNA is double-stranded. DNA has a helical shape. DNA is antiparallel.
DNA is flexible
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 overall conclusion of the Hershey-Chase experiment was that DNA was responsible for heredity proteins and DNA were responsible for heredity the ratio of Adenine to thymine was always the same phage DNA was similar to bacterial DNA
DNA was responsible for heredity
What was the significance of Frederick Griffith's experiments with Streptococcus pneumoniae?
He showed that the DNA from strain S cells could transform strain R cells.
Which of the following separates the DNA strands during replication? helicase primase DNA polymerase I DNA polymerase III ligase
Helicase
In which direction does the replication fork move?
It moves ahead of the newly synthesized DNA.
Replication in prokaryotes differs from replication in eukaryotes for which of these reasons? The prokaryotic chromosome has histones, whereas eukaryotic chromosomes do not. Prokaryotes have telomeres, and eukaryotes do not. Prokaryotes produce Okazaki fragments during DNA replication, but eukaryotes do not. Prokaryotic chromosomes have a single origin of replication, whereas eukaryotic chromosomes have many. The rate of elongation during DNA replication is slower in prokaryotes than in eukaryotes.
Prokaryotic chromosomes have a single origin or replication, whereas eukaryotic chromosomes have many.
What ensures that the single strands of DNA do not come back together? ATP DNA helicase Stabilizing proteins The replication fork
Stabilizing proteins
How do stabilizing proteins work on the DNA? They bind to the single-stranded DNA. They bind to the double-stranded DNA. They form the replication fork. They use ATP to break the hydrogen bonds
They bind to single-stranded DNA.
What is the function of connector proteins?
They link the leading strand DNA polymerase and the lagging strand DNA polymerase together.
The structure of DNA explains both its ability to encode genetic information and the way in which it is copied during cell reproduction. True False
True
What are the products of semiconservative replication for a double-stranded DNA molecule?
Two double-stranded DNA molecules, each consisting of one parental strand and one daughter strand.
Which of the following is found at the 5 end of a DNA strand? a hydrogen bond a hydroxyl group histones a phosphate group a methyl group
a phosphate group
Which of the following covalently connects segments of DNA? helicase DNA polymerase III DNA polymerase I primase ligase
ligase
The Ames test proves that a chemical is carcinogenic in humans. mutagenic in humans. carcinogenic. mutagenic in Salmonella. carcinogenic in Salmonella
mutagenic in Salmonella.
Which of the following can be determined directly from X-ray diffraction photographs of crystallized DNA? the rate of replication the frequency of A vs. T nucleotides the bond angles of the subunits the sequence of nucleotides the diameter of the helix
the diameter of the helix
The leading strand and the lagging strand 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.
______________________ is the overall direction of two ____________________ strands of DNA relative to one another so that the _________________ run opposite of each other.
Antiparallel; complementary; 5' to 3' orientations
Which is the largest among the followings? Nucleotide Nitrogenous base Phosphate Carbon
Nucleotide
Stages in which the lagging strand is synthesized:
1. DNA polymerase begins synthesizing the lagging strand by adding nucleotides to a short segment of RNA. 2. After each strand of the lagging strand is complete, it is released from the DNA polymerase. 3. A different DNA polymerase replaces the RNA segments with DNA. 4. DNA ligase seals the gaps between the pieces, and eventually forms a continuous strand.
A DNA strand with the sequence 3' GTGAACTGC 5' is complementary to the sequence
5' GCACTTCAC 3'
Which of the following is true of DNA replication? The preexisting strand is read in the 5' _ 3' direction. The new strand is made in the 3' _ 5' direction. An RNA primer is needed to begin DNA synthesis. All of the above are true of DNA replication. More than one, but not all, are true of DNA replication.
An RNA primer is needed to being DNA synthesis.
The higher order structure of DNA shows symmetry, whereas the higher order structures of most proteins do not. Why isn't protein shape more regular like DNA? DNA has one main function in cells whereas proteins have many. The many different amino acid R groups on proteins confer many different shapes. Some S amino acids cause proteins to bend; others cause protein to flatten. All of the above
All of the above.
Which of the following are terms associated with Okazaki fragments? Discontinuous DNA ligase Lagging strand Lagging strand, DNA ligase, and discontinuous
Lagging strand, DNA ligase, and discontinuous
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? No proofreading will occur. Replication will require a DNA template from another source. The DNA will supercoil. Replication will occur via RNA polymerase alone. No replication fork will be formed.
No replication fork will be formed.
In a healthy cell, the rate of DNA repair is equal to the rate of DNA mutation. When the rate of repair lags behind the rate of mutation, what is a possible fate of the cell?
The cell can be transformed into a cancerous cell
Chargaff'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.
An Okazaki fragment has which of the following arrangements? 3' RNA nucleotides, DNA nucleotides 5' DNA polymerase I, DNA polymerase III primase, polymerase, ligase 5' DNA to 3' 5' RNA nucleotide, DNA nucleotide 3'
5' RNA nucleotide, DNA nucleotide 3'
In an analysis of the nucleotide composition of DNA, which of the following will be found? G + C = T + A A = G and C = T A = C A + C = G + T
A + C = G + T
Which of the following best describes the addition of nucleotides to a growing DNA chain? A nucleoside diphosphate is added to the 3' end of the DNA, releasing a molecule of phosphate. A nucleoside triphosphate is added to the 3' end of the DNA, releasing a molecule of pyrophosphate. A nucleoside triphosphate is added to the 5' end of the DNA, releasing a molecule of pyrophosphate. A nucleoside monophosphate is added to the 5' end of the DNA. A nucleoside diphosphate is added to the 5' end of the DNA, releasing a molecule of phosphate.
A nucleoside diphosphate is added to the 3' end of the DNA, releasing a molecule of phosphate.
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.
The molecule that seals the gaps between the pieces of DNA in the lagging strand is RNA. the leading strand. DNA ligase. DNA polymerase. the replication fork.
DNA ligase
Which statement about DNA replication is FALSE? DNA ligase adds nucleotides to the lagging strand. The two strands of parental DNA are separated during DNA replication. DNA polymerase builds a new strand by adding DNA nucleotides one at a time. Because the two strands of parental DNA run in opposite directions, the new strands must be made in different ways. The lagging strand is made of a series of pieces that must be joined together to make a continuous strand.
DNA ligase adds nucleotides to the lagging strand.
Which of the following build(s) new strands of DNA? The origins of replication DNA polymerases The lagging strand The leading strand Parental DNA
DNA polymerase Correct; DNA polymerases build new strands of DNA by adding DNA nucleotides one at a time.
Which of the following removes the RNA nucleotides from the primer and adds equivalent DNA nucleotides to the 3' end of Okazaki fragments? ligase DNA polymerase I primase DNA polymerase III helicase
DNA polymerase I
What is the function of the parental DNA in replication?
It serves as the template for DNA replication.
Which DNA strand is synthesized continuously? Lagging strand Neither the leading nor the lagging strand is synthesized continuously. The leading and lagging strands are both synthesized continuously. Leading strand
Leading strand.
You briefly expose bacteria undergoing DNA replication to radioactively labeled nucleotides. When you centrifuge the DNA isolated from the bacteria, the DNA separates into two classes. One class of labeled DNA includes very large molecules (thousands or even millions of nucleotides long), and the other includes short stretches of DNA (several hundred to a few thousand nucleotides in length). These two classes of DNA probably represent
Leading strands and Okazaki fragments
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.
Which of the following help to hold the DNA strands apart while they are being replicated? single-strand binding proteins primase exonuclease ligase DNA polymerase
Single-stranded binding proteins
During DNA replication, which nucleotide will bind to an A nucleotide in the parental DNA? T A C G U
T
Which statement about DNA replication is CORRECT? DNA ligase helps assemble the leading strand. The lagging strand is one of the strands of parental DNA. The leading strand is one of the strands of parental DNA. The lagging strand is built continuously. The leading strand is built continuously, and the lagging strand is built in pieces.
The leading strand is build continuously, and the lagging strand is built in pieces.
Why is the DNA synthesis of the lagging strand considered discontinuous?
The synthesis is moving in the opposite direction from the replication fork.
The enzyme telomerase solves the problem of replication at the ends of linear chromosomes by which method?
adding numerous short DNA sequences such as TTAGGG, which form a hairpin turn
