Genetic variation of viruses 10

Previous exams & Formative:

1- Mutations that can multiply under some conditions but not under other conditions are: a. Plaque-size mutants b. Conditional-lethal mutants c. Host-range mutants d. Drug-resistant mutants

2- Mutation that induce changes in diameter of the zone of viral lysis in infected cell monolayers are: a. Plaque-size mutants b. Conditional-lethal mutants c. Host-range mutants d. Drug-resistant mutants

3- A sudden change in the sequence of DNA or RNA is called: a. Change b. Alteration c. Mutation d. Transduction

Extra:

1- A mutation is defined as: a. A change in the cells structure b. Anything that changes in an embryo c. Any change in the physical features of a human d. A change in the DNA sequence

2- The mutation results in the replacement of an amino acid codon by a termination (stop) codon called: a. Host-dependent mutants: b. Enzyme-deficient mutants c. Hot mutants d. None of the above

3- When a single nucleotide base pair is substituted, the type of mutation occurs is: a. random mutation b. point mutation c. inversion d. mispairing

4- The mutations that are valuable in determining the function of the viral gene is called: a. Substitution b. Frameshift mutation c. Conditional lethal mutation d. Point mutation

5- Mechanism of virus interference includes all of the following except: a. Blocking its receptors or by destroying its receptors. b. The cell enzymes necessary for viral growth are under the direction of the1st virus. c. The 1st virus stimulates the infected cell to produce an inhibitor (interferon) that prevents the replication of the 2nd virus d. Phenotypic mixing

6- Between two chromosomes the exchange of gene is called as: a. Interaction b. Mutation c. Recombination d. Point mutation

7- Drug-resistant mutants are: a. The mutation usually affects an enzyme that is inhibited by the antiviral drug. b. mutants occur when a whole segment of the viral genome is lost. c. Mutations here induce changes in the diameter of the zone of viral lysis seen in infected cell monolayers. d. All of the above

8- In the virus growth cycle; transmission of the virus particle or the nucleic acid from the surface of the infected cell to the interior of the cells is known as: a. Penetration b. Recognition c. Assembly d. None of the above

9- When Two viruses enter the same cell, replicate independently and produce their own characteristic type of infection, this is known as: a. Dual infection b. Recombination c. Reassortment d. Complementation

Previous exams & Formative:

1- Genetic reassortment occurs in: a. Viruses with segmented genome b. Defective viruses c. Viroids d. Prions

2- Exaltation means: a. One virus enhances the growth of the other virus b. No sense mutation c. Genetic reassortment of virus genome d. Point mutation in the genome a. DNA b. RNA c. DNA or RNA d. DNA and RNA

3- Which of the following is the genome of the virus?

Extra:

1- In some mixed infection one virus may enhance the growth of the second virus occurs in: a. Dual infection b. Exaltation c. Recombination d. Reassortment

2- Two viruses can enter the same cell, replicate independently and produce their own characteristic type of infection in: a. Dual infection b. Exaltation c. Recombination d. Reassortment

3- Which the This mechanism applies only to viruses with segmented genomes: a. Exaltation b. Dual Infection c. Recombination d. Reassortment

4- Which This is the way in which defective tumor causing retroviruses propagate and spread in nature: a. Exaltation b. Reassortment c. Interference d. Complementation

5- In the process of assembly of progeny virions, hybrid capsids constituted by subunits coded by the two different viruses may be generated is: a. Phenotypic mixing b. Pseudotype formation c. All of the above d. None of the above

6- Phenotypic masking is a: a. The genetic process resulting in pseudotype formation b. The genetic process resulting in Phenotypic mixing c. All of the above d. None of the above

7- Antigenic drift of viruses is caused by Select one: a. Recombination b. Reassortment c. Mutation d. Mutation and reassortment

8- All of the following are Mechanisms of viral interference except: a. One virus may inhibit the ability of the 2nd to adsorb to the cell, either by blocking its receptors or by destroying its receptors b. The cell metabolites or enzymes necessary for viral growth are taken by or are under the direction of the 1st virus c. The 1st virus may stimulate the infected cell to produce an inhibitor (interferon) that prevents the replication of the 2nd virus d. None of the above

9- In Interference the first virus is called: a. Activated virus b. Suppressed virus c. Interfering virus d. None of the above

10- In Interference the second virus is called: a. Activated virus b. Suppressed virus c. Interfering virus d. None of the above