BIOL 1107 CH 16 Review
Given a template strand of 3'-ATGCTTGGACA-5' and a partially-made complementary strand containing only 5'-TAC-3', what would be the sequence of the new strand of DNA (including the 5'-TAC-3') if the only additional nucleotides available to DNA polymerase were those containing the bases G, A, and C?
5'-TACGAACC-3'
In analyzing the number of different bases in a DNADNA sample, which result would be consistent with the base-pairing rules?
A+G=C+T
Duplication of chromosomes occurs during S phase of the cell cycle. Duplication requires the separation of complementary DNA strands to allow for DNA replication. Which of the following statements best explains how weak hydrogen bonds function better in this situation than stronger bonds would?
Complementary DNA strands are separated or "unzipped" for the replication process. Weak hydrogen bonds between complementary strands are easily disrupted during DNA replication because they are not high-energy chemical bonds.
A DNA molecule consists of two antiparallel strands of polynucleotides. Each strand is composed of nucleotides bound to each other along the sugar-phosphate backbone. Drag "True" or "False" to the end of each statement.
Complementary base pairing relies on the number of hydrogen bonds that each base can make. True In a single nucleotide, the phosphate group is attached to the 5' carbon of the sugar unit. True The -OH group on the 3' carbon of the sugar unit is the attachment site for the nitrogenous base. False The antiparallel arrangement of double-stranded DNA is due to the phosphate group being bonded to the 3' carbon on one strand and the 5' carbon on the complementary strand. False The phosphate attached to the 5' carbon of a given nucleotide links to the 3' -OH of the adjacent nucleotide. True
Which of these is responsible for catalyzing the formation of an RNA primer?
D
The radioactive isotope 32P labels the T2 phage's _____.
DNA
What are chromosomes made of?
DNA and proteins
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 role of DNA polymerase during DNA synthesis?
DNA polymerase is the enzyme that catalyzes the addition of a nucleotide onto the 3' end of a growing DNA strand.
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.
What is the basis for the difference in how the leading and lagging strands of DNADNA molecules are synthesized?
DNADNA polymerase can join new nucleotides only to the 3′3′ end of a pre-existing strand, and the strands are antiparallel.
DNA replication is said to be semiconservative. Which of the following statements correctly explains what this means?
Each new double helix consists of one old and one new strand.
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. Rank the primers in the order they were produced. If two primers were produced at the same time, overlap them.
Earliest: A,H B,G C,F Latest: D,E
Who conducted the X-ray diffraction studies that were key to the discovery of the structure of DNA?
Franklin
Who demonstrated that DNA is the genetic material of the T2 phage?
Hershey and Chase
The synthesis of a new strand begins with the synthesis of a(n) _____.
RNA primer complementary to a preexisting DNA strand
Addition of a nucleotide onto a DNA strand is an endergonic reaction. What provides the energy to drive the reaction?
Release of pyrophosphate from the incoming nucleotide, and then hydrolysis of the pyrophosphate to inorganic phosphate
Various types of chemical bonds or interactions maintain the three-dimensional (3D) structure of large biological molecules like DNA. Not all types of bonds or interactions are shown in all diagrams. The types of bonds or interactions shown depend on the emphasis of the particular diagram. Which of the following diagrams most clearly shows the overall 3D shape and atomic composition of DNA?
Space Filling model
Which of the following diagrams most clearly shows the details of the bonds between nitrogenous bases of complementary nucleotide pairs?
Structural Diagram
In DNA replication in bacteria, the enzyme DNA polymerase III (abbreviated DNA pol III) adds nucleotides to a template strand of DNA. But DNA pol III cannot start a new strand from scratch. Instead, a primer must pair with the template strand, and DNA pol III then adds nucleotides to the primer, complementary to the template strand. Each of the four images below shows a strand of template DNA (dark blue) with an RNA primer (red) to which DNA pol III will add nucleotides. In which image will adenine (A) be the next nucleotide to be added to the primer?
T, CG, GC, CG, A
Drag the terms on the left to the appropriate blanks on the right to complete the sentences.
The bonds or interactions that hold together adjacent nucleotides in the sugar-phosphate backbone of DNA are covalent bonds. The bonds or interactions that hold together complementary bases from opposite strands of DNA are hydrogen bonds. The bonds or interactions between stacked nucleotide units that help hold the DNA molecule together are van der Waals interactions.
DNA is a double-stranded molecule made up of complementary, antiparallel strands. Based on what you know about complementary base pairing, fill in the rest of the details in the figure.
Top left is OH the rest is correct on picture
A hydroxyl is present at the 3' end of the growing DNA strand. What is at the 5' end?
a phosphate group
The DNA double helix is composed of two strands of DNA; each strand is a polymer of DNA nucleotides. Each nucleotide consists of a sugar, a phosphate group, and one of four nitrogenous bases. The structure and orientation of the two strands are important to understanding DNA replication. Drag the labels to their appropriate locations on the diagram below. Targets of Group 1 can be used more than once.
a) 5' end b) hydrogen bond c) 3' end d) deoxyribose sugar e)nitrogenous base f)phosphate group g)3' end h)5' end
The diagram below shows a bacterial replication fork and its principal proteins. Drag the labels to their appropriate locations in the diagram to describe the name or function of each structure.
a. Breaks hydrogen bonds, unwinding DNA double helix .b. Synthesizes RNA primers on leading and lagging strands. c. Replaces RNA primers with DNA nucleotides. d. Catalyzes phosphodiester bond formation, joining DNA fragments. e. Lagging strand f. Leading strand g. Relaxes supercoiled DNA .h. Coats single-stranded DNA. i. Synthesizes DNA 5' to 3' on leading and lagging strands.
The elongation of the leading strand during DNADNA synthesis
depends on the action of DNADNA polymerase.
After DNA replication is completed, _____.
each new DNA double helix consists of one old DNA strand and one new DNA strand
The first step in the replication of DNA is catalyzed by _____.
helicase
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
In nucleotide excision repair, damaged DNA is excised by what enzyme(s)?
nuclease
E. coli cells grown on 15N15N medium are transferred to 14N14N medium and allowed to grow for two more generations (two rounds of DNADNA replication). DNADNA extracted from these cells is centrifuged. What density distribution of DNADNA would you expect in this experiment?
one low-density and one intermediate-density band
This is an image of a _____.
phage
The action of helicase creates _____.
replication forks and replication bubbles
What materials does DNA polymerase require in order to synthesize a complete strand of DNA?
single-stranded DNA template 3'-OH end of the new DNA strand all four deoxyribonucleotides triphosphates (containing A, C, T, or G)
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
Hershey and Chase used _____ to radioactively label the T2 phage's proteins.
35S
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. Drag the labels to their appropriate locations in the flowchart below, indicating the sequence of events in the production of fragment B. (Note that pol I stands for DNA polymerase I, and pol III stands for DNA polymerase III.)
1 Pol III binds to 3' end of primer B 2 Pol III moves 5' to 3' 3 Pol I Binds to 5' end primer A 4 Pol I replaces primer A with DNA 5 DNA ligase links fragments A and B
Complete the following vocabulary exercise related to DNA replication. Match the words in the left-hand column with the appropriate blank in the sentences in the right-hand column.
1. The enzyme that can replicate DNA is called DNA polymerase. 2. During DNA replication, an open section of DNA, in which a DNA polymerase can replicate DNA, is called a replication fork. 3. Okazaki fragments are the short sections of DNA that are synthesized on the lagging strand of the replicating DNA. 4. After replication is complete, the new DNAs, called daughter DNA, are identical to each other. 5. The new DNA strand that grows continuously in the 5' to 3' direction is called the leading strand.
As 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. Sort the phrases into the appropriate bins depending on which protein they describe.
helicase - breaks H-bonds between bases; binds at the replication fork topoisomerase - breaks covalent bonds in DNA backbone; binds ahead of the replication fork single-strand binding - prevents H-bonds between bases; binds after the replication fork
In a nucleosome, the DNADNA is wrapped around
histones
Which of the following is true of DNA during interphase?
it exists as chromatin and is less condensed than mitotic chromosomes
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. Drag each phrase to the appropriate bin depending on whether it describes the synthesis of the leading strand, the synthesis of the lagging strand, or the synthesis of both strands.
leading strand: daughter strand elongates toward replication fork, only one primer needed, made continuously lagging strand: made in segments, daughter strand elongates away from replication fork, multiple primers needed both strands: synthesized 5' to 3'
Short segments of newly synthesized DNA are joined into a continuous strand by _____.
ligase
