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Example Questions
Example Question #21 : Understanding Viruses And Prions
Which of the following is true of a bacteriophage?
It always contain a circular DNA plasmid
It can infect only plants or fungi
It contains its own ribosomes
It is engulfed entirely by the host cell
Only its DNA enters the host cell
Only its DNA enters the host cell
A bacteriophage is a virus which attacks bacteria and consists of a head, tail, and tail fibers all made of protein. The head contains genetic material (usually linear DNA) which is injected into the host bacterium upon infection. The protein parts do not enter the bacterium, and it does not have any ribosomes or organelles of its own.
Example Question #959 : Ap Biology
Some vaccines are developed through attenuation of the actual viral organism. Attenuation occurs through giving the pathogen a nutrient rich environment to replicate in thus mutation occurs in virulence factors normally adapted by the virus for survival.
Which of these is a reason attenuation of the West Nile Virus for a suitable human vaccine has not occurred as yet?
A chicken can develop the symptoms and an immune response to the West Nile Virus thus putting the virus back into competition to remain virulent
A horse can develop the symptoms and an immune response to the West Nile Virus thus putting the virus back into competition to remain virulent
Neuronal cell culture techniques have been unsuccessful in surviving replication of the virus
All of these
Human blood cell lines can are a target of the West Nile Virus thus putting the virus back into competition to remain virulent
All of these
The three main media of attenuating a virus are infecting birds, horses, or cultured cell lines. West Nile Virus is an interesting virus in that host and susceptible organisms happen to be birds, horses, and humans. This virus also does not seem to replicate in other animal reservoirs such as lizards. It does not replicate in mosquitos. Moreover, recent attempts to culture a neuronal cell line to replicate the virus have been unsuccessful due to the extended length of life cycle of neuronal cells.
Example Question #22 : Understanding Viruses And Prions
What novel enzyme to retroviruses employ to convert their RNA genomes into DNA?
Reverse translatase
DNA synthase
DNA polymerase
Reverse transcriptase
RNA replicase
Reverse transcriptase
Retroviruses employ the enzyme reverse transcriptase to convert their RAN genomes into DNA.
Example Question #22 : Understanding Viruses And Prions
Which of the following describes the enzyme reverse transcriptase?
An RNA dependent DNA polymerase
A DNA dependent RNA polymerase
An RNA dependent RNA polymerase
A DNA dependent DNA polymerase
An RNA dependent protein polymerase
An RNA dependent DNA polymerase
Reverse transcriptase binds RNA and catalyzes the formation of a complementary DNA molecule. Since it needs an RNA template to work, this enzyme is RNA dependent. Since it forms a DNA molecule, this enzyme is a DNA polymerase. Recall the chemical difference between DNA and RNA - DNA lacks a hydroxide group at the 3' position of the ribose sugar, which makes it deoxyribose.
Example Question #23 : Understanding Viruses And Prions
Which of the following do retroviruses and bacteriophages have in common?
They can both enter the lysogenic cycle
The both have only RNA genomes
They both only infect prokaryotes
The both use reverse transcriptase
They can both enter the lytic cycle
They can both enter the lysogenic cycle
The lysogenic cycle occurs when a virus incorporates its DNA into the host genome. It stays inside the host genome, getting replicated along with the host until conditions are right when it excises itself and beings the process of hijacking the cell to make more virus. Both retroviruses and bacteriophages can undergo this process.
Example Question #24 : Understanding Viruses And Prions
Prions represent misfolded versions of what biological macromolecule?
Carbohydrates
Nucleic acids
Proteins
Vitamins
Lipids
Proteins
Prions are proteins that are folded in alternate conformations. The molecules can then produce a disease state by catalyzing the misfolding of additional proteins in the cell. Note that vitamins are not one of the four classical biological macromolecules.
Example Question #25 : Understanding Viruses And Prions
Viral genomes may consists of which of the following nucleic acids?
I. Double-stranded DNA
II. Single-stranded DNA
III. Double-stranded RNA
IV. Single-stranded RNA
I, II, and III
II, III, and IV
I and II
I, II, III, and IV
I and IV
I, II, III, and IV
The nucleic acids that make up viral genomes are very diverse. Viral genome can consist of both double and single stranded DNA as well as double and single stranded RNA.
Example Question #26 : Understanding Viruses And Prions
Reverse transcriptase is __________.
produced by viruses and is used to inhibit normal DNA transcription
produced by the infected cell and used to inhibit viral transcription
produced by viruses and used by the infected cell to transcribe viral RNAs that will be translated by the cell into viral proteins
produced by viruses and used by the cell to transcribe viral DNA that will be inserted into the genome of the infected cell
produced by the infected cell and used to transcribe RNAs that will be translated by the cell into antibodies against viruses
produced by viruses and used by the cell to transcribe viral DNA that will be inserted into the genome of the infected cell
Reverse transcriptase is a viral enzyme used by some viruses to transcribe double-stranded DNA from their single-stranded RNA, which is the exact opposite of the normal transcription process of the cell. The double-stranded viral DNA is then able to integrate into the double-stranded DNA of the infected cell’s genome so that whenever the cell divides, all of its daughter cells will carry the viral DNA. This viral DNA can eventually be transcribed by the cell’s own enzymes to produce viral RNA. Some of the viral RNA will be translated into viral proteins, and new viruses will be assembled from these products.
Example Question #27 : Understanding Viruses And Prions
Which of the following is not true about viruses?
In the lytic cycle, the new viruses break out from the cell, killing its host.
In the lysogenic cycle, the virus replicates its genome and kills its host.
In the lysogenic cycle, the viral genome is embodied into the bacterial chromosome through genetic recombination.
Some viruses only use the lytic cycle.
In the lysogenic cycle, the virus replicates its genome without killing its host.
In the lysogenic cycle, the virus replicates its genome and kills its host.
In the lysogenic cycle, a virus replicates its genome but does not kill the host. The host lives and reproduces normally, and the daughter cells can inherit the prophage (the bacterial circular chromosome and the bacteriophage genome)
Example Question #28 : Understanding Viruses And Prions
Which of the following is characteristic of viruses?
Cell wall made of chitin
Membrane bound organelles (e.g., Golgi apparatus)
Thick peptidoglycan cell wall
Lipid bilayer outer membrane
A protein coat
A protein coat
Viruses are unique organisms in that they have a relatively simple cell structure. They have an outer protein coat, which sets them apart from other organisms. Peptidoglycan is found in bacteria, lipid bilayer is found in eukaryotic cells, and chitin is found in fungi. Membrane-bound orangelles are found in more complex cells, such as eukaryotic cells, and are not unique to viruses.
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