The synthesis of new DNA from parental DNA involves which three steps?
Initiation, elongation, and termination
In order for DNA to replicate in a semi-conservative manner, what must occur?
1. The double stranded parent DNA molecule must be separated by breaking he hydrogen bonds between the nitrogenous bases.
2. Both parent strands of DNA must serve as a template fr the synthesis of the new strands
3.The parent strands of DNA must re-anneal after serving as a template for the synthesis of new
1 and 2
E. Coli chromosomes
adopt a υ-shaped conformation during replication!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Since the parental double helix must rotate 360 degrees to unwind each gyre of the helix, during the semi-conservative replication of the bacterial chromosome, some kind of "swivel" must exist. What do geneticists now know that the required swivel is?
A transient single-strand break produced by the action of topisomerase I
How many origins of replication are typically found in a bacterial or viral chromosome?
In the E. coli chromosome the origin of replication, called oriC, is characterized as being rich in
A-T base pairs
A replication bubble is
A localized region of DNA strand separated in which replication occurs in a bidirectional direction consisting of two replication forks
What purpose is served by DNA ligase?
To repair single-stranded discontinuities in double stranded DNA molecules by repairing a phosphodiester bond between phosphates in the backbone
Consider the DNA template to be used for the replication
Which of the following choices shows the correctly replicated new strand of DNA?
Consider the replicated strand of DNA
Which of the following choices shows the template strand of DNA used for replication?
A researcher is attempting to replicate DNA in vitro. He adds all of the components to the tube except Mg2+. What kind of result can he expect to observe?
The DNA will not replicate because DNA polymerase will not be active
The direction of DNA synthesis is
A researcher is attempting to replicate DNA in vitro. All necessary components are added, however, the DNA that is used does not have a free 3' hydroxyl. What kind of result is expected?
The DNA will not replicate because DNA polymerase can not add dNTPs to the existing DNA
Which of the following is a true function of DNA polymerase I?
2. 5'-->3' exonuclease
3. 3'-->5' exonuclease
2 and 3
Which DNA polymerase molecule acts as the replicase in E. coli?
DNA polymerase III
Which of the following characteristics is not commonality between prokaruotic and eukaryotic DNA polymerase?
They consist of a single polypeptide chain
Proofreading activities of E. coli DNA polymerase is carried out by
Polymerase I by the 3'-->5' exonuclease activity
Complementary strands of a DNA double helix have opposite chemical polarity but are synthesized in the same direction (replication fork movement). This is accounted for by
Using the 5'-->3' polymerase activity of Pol III to synthesize multiple short segments which are later covalently joined
DNA replication requires a free 3'-OH to initiate polymerase activity. This is accomplished by synthesizing
A temporary RNA primer removed by Pol I
During replication, the double helix undergoes torsional stress during strand separation and polymerase activity. Several proteins are employed to counter this stress and assist strand separation. Which of the following proteins involved with this process is defined incorrectly below?
Topoisomerase I: removes and introduces positive supercoils one at a time
Rolling circle replication
Is initiated by a single exxonucleolytic cleavage event
One similarity between prokaryotic and eukaryotic DNA replication is
Distinct leading and lagging strands
In eukaryotes, two DNA polymerases were found to be essential to leading and lagging strand synthesis of the SV40 virus. They are
Which of the following statements about telomerase are true:
1. It extends the 3' end of a linear chromosome one repeat at a time
2. It uses a built-in DNA to act as a template for synthesis of the telomeric repeat
3. Without telomerase, linear chromosomes would become progressively shorter.
1 and 3
Which subunit of the Pol III enzyme forms a ring-like structure around DNA, acting like PCNA in eukaryotes, in order to increase the enzyme's processitivity?
Before direct proof of DNA being the genetic material, indirect evidence suggesting DNA as the appropriate macromolecule (per the chapter in the book) included:
Gametes have 1/2 the amount of DNA as somatic cells
Molecular composition of DNA is the same in different cells of an organism, whereas RNA and protein contents vary.
A correlation between DNA content and the number of chromosome sets per cell.
DNA is more stable than RNA or protein.
All of the answers are correct
Infectious agent that contains small circular pieces of RNA that are not packaged in a protein coat are known as
Infectious agents that contain only altered forms of protein and no nucleic acid are known as
The pathogenic effects of prions are thought to result from
Aberrant forms of mammalian cellular proteins that convert more mammalian cellular proteins to aberrant forms, leading to a clumping of the proteins, eventually killing the cell
Which of the following is true regarding the structure of RNA?
Single stranded molecule and composed of nucleotides
Which of the following is not accurate according to Chargaff's rules?
A + T = C + G
Which type of chemical bond attaches deoxyribose molecules together to form the backbone of a DNA molecule?
Single strand of a double-stranded helix has the sequences
If the helix was in B-form, how many turns (360 degrees) would the helix make?
DNA extracted from a bacterium was identified as having a guanine content of 14%. From this information determine the percentage of A.
Under wound DNA is said to exhibit:
Functional DNA molecules in cells typically exhibit:
Prokaryotic chromosome structure:
Has 50 to 100 domains or loops, each of which is independently negatively supercoiled
Which class of proteins is associated with DNA in chromatin?
Histones and Non-histone chromosomal proteins
Three levels of condensation are required to package metaphase chromosomes. In order of complexity, lowest to highest, they are:
Supercoiling into nucleosomes, chromatin fiber condensation, scaffold formation
Satellite DNA is:
The function associated with telomeres are to
Facilitate replication of chromosomes without the loss of termini
While discussing the structure of DNA with your classmates you notice that your study partner has drawn a DNA molecule that looks like the following.
What is incorrect about this drawing?
Hydrogen base pairing of nucleotides is incorrect
What were the teo major pieces of evidence that led to the deduction of DNA structure by Watson and Crick?
A-T and C-G basepairing and X-ray diffraction
Which of the following statements is false with regards to bacteria as a model organism for genetic study?
Genetic variability is difficult to detect
Which of the following statements is true with regards to viruses?
1. Viruses can only reproduce by infecting living cells.
2. Viruses can be considered both living and non-living depending on the state they are in
3. Viruses that infect bacterial cells are known as bacteriophages
1, 2, 3
Which of the following is a true statement bout the phage T4?
1. It is a temperate phage
2. It is a virulent phage
3. It can infect a bacterium E. coli
2 and 3
Temperate and virulent phages differ in that
Virulent phages kill the host cell and temperate phages can kill the host cell or live in a symbiotic state with the host cell
T4 contains a modified DNA base. Which base is modified and for what purpose?
Cytosine; to protect phage DNA from phage encoded DNAse
In a lysogenic pathway, the viral DNA is:
1. Inserted into the host chromosome
2. Replication with the host chromosome
3. Integrated by site specific recombination
1, 2, 3
When bacteriophage λ integrates into the bacterial chromosome, it does so at:
An attB site in the host chromosome using a lambda-encoded integrase
The lambda phage can cause lysis in a bacterium when:
1. The lambda DNA is spontaneously excised from the host chromosome
2. The lambda DNA is induced to excise from the host chromosome
3. The lambda DNA excises from the host chromosome and moves back into the phage
1 and 2
In a mixed infection of T4 of genotype h+r X hr+ (where h is the mutant that produces clear plaques and r is h mutant that produces sharp edges) on a mixture of E. coli B and B2 cells, wild type recombinats form:
Turbid plaques with fuzzy edges
Gene transfer in bacteria is:
Unidirectional- from donor cells to recipient cells
1. Autonomously replicating
3. Extrachromosomal DNA
1, 2, 3
Which of the following is true regarding bacteria?
Bacteria reproduce by simple fission
Bacteria are monoploid and multinucleate
Bacteria do not undergo mitosis
Bacteria do not undergo meiosis
All of these are true
Wild type bacteria that can synthesize all necessary metabolites are know as
A mutant of E. coli is designated Str and arg-. Which of the following best describes this genotype?
antibiotic resistant, prototrophic
With rare exceptions, after gene transfer occurs through conjugation or transduction in bacteria, the recipient cells become:
Recombination between bacteria occurs between:
The main chromosome of the recipient and a fragment of the donor.
While conducting research you notice that when DNAse is added to the medium, genetic exchange no longer occurs in your bacteria. What can you conclude about the method of genetic exchange that was occurring?
Transformation was taking place before the addition of DNAse
Cells that are capable of DNA uptake are known as
In F factor mating, which of the following statements is incorrect?
Recombination can occur between IS in the F factor and chromosome to generate F' cells
Is carried out using interrupted mating experiment
Which form of replication mediates the transfer of chromosomes from Hfr cells to F- cells?
Rolling circle replication
Which of the following statements is not correct about specialized transduction?
It requires precise excision of the integrated prophage to transfer chromosomal markers
A Hfr strain is produced by:
The integration of the F factor into a bacterial chromosome
Mammalian DNA polymerases are different than bacterial enzymes. Which of the following is not true about mammalian enzymes?
Alpha, beta, gamma, delta, and epsilon are the subunits of larger enzyme complexes
Which of the following does not characterize a t-loop:
The number of repeats in this region is highly conserved within and between species.
Is nucleosome free with a specific motif of 110 nucleotides
Because of ______, the error rates in DNA replication are as low as one error per 10,000 to 100,000 nucleotides.
Draw a replication bubble. You are to include the following
1. All the enzymes necessary for this process to occur in E. coli
2. The specific roles and abilities of each of the enzymes listed above
3. All orientations for the DNA strands, RNA primers and origins.
4. All accessory proteins necessary for successful replication.
5. Craw the typical E. coli origin (oriC) and the essential components of this structure.