Question

1. Which of the following criteria is not part of the ICTV classification system?
a. genome composition d. envelope
b. particle size e. spike proteins
c. Capsid symmetry f. host range

2. A viral Capsid is comprised of
a. nucleis acids c. carbohydrates
b. proteins d. lipopolysaccharides

3. fill in the blanks
In the Baltimore classification system, there are __________ classes of DNA viruses and __________ classes of RNA viruses (enter a number for each blank)

4. Plus strand RNA is
a. the mRNA c. the template strand
b. the coding strand d. the complement of the mRNA

5. fill in the blank
Reverse Transcriptase is an enzyme that catalyzes ____________ production from a ___________ template.

Answer 1

Q1) Which of the following criteria is not a part of the ICTV classification system-

Answer- E- Spike protein.

Explanation- ICTV is the International Committee For Taxonomy of Viruses , the classification is based on these cateogories they are- i) Structure of capsid, ii) Presence or absence of envelop iii) Size of virion iv) Type of host and v) Genome composition. spike protein is not considered as a criteria for ICTV classification.

Q2) A viral capsid comprised of-

Answer- B- Proteins.

Explanation- A viral capsid is made up of proteins,It contains several oligomeric structural subunits made of proteins called protomers.

Q3) FIll in the blanks - In the Baltimoore classification system there are _________ classes of DNA viruses and ______ classes of RNA viruses (Enter a number in each blank).

Answer- 3 classes of DNA virus and 4 classes of RNA virus.

Explanation - According to Baltimore system of virus classification viruses are placed under seven groups, based on a combination of their nucleic acid (DNA or RNA), strandedness (single-stranded or double-stranded), Sense (+ or - ), and their method of replication.

Classes of DNA viruses are

i) Double stranded (d.s.) DNA virus ( Adenoviruses, Herpesviruses).

ii) s.s.DNA virus (+ sense) virus . (Parvoviruses)

iii) d.s..DNA RT virus.DNA with RNA intermediate in life-cycle ( Hepadnaviruses)

Classes of RNA virus :-

i)  dsRNA viruses (e.g. Reoviruses).

ii) (+)ssRNA viruses (+ strand or sense) RNA virus ( Picornaviruses, Togaviruses).

iii)  (?)ssRNA viruses (? strand or antisense) RNA ( Orthomyxoviruses, Rhabdoviruses)

iv)  ssRNA-RT viruses (+ strand or sense) RNA with DNA intermediate in life-cycle ( Retroviruses)

Q4) Plus strand RNA is -

Answer-A - m-RNA

Explanation- Viral genome having +ve configuration, act directly as mRNA.it can be directly translated into the required viral protein. so viral genome considered as viral mRNA .

Q5) Fill in the blanks-

Reverse transcriptase is an enzyme that catalyzes ___cDNA_____ production from a __RNA______ template.

Explanation- It is used to generate complementary DNA (c DNA) from an RNA template, the process is called reverse transcription. It is mostly found in retroviruses .