Question

Viruses- Bacteriology

-Describe the characteristics of viruses.

-Explain receptors for bacterial viruses (bacteriophage).

-How do bacteria prevent the invasion of foreign nucleic acids?

-What is reverse transcriptase and which viruses use it?

-What type of nucleic acids is in many important human disease-causing viruses?

-List the possible consequences of viral infection of an animal cell?

-Differentiate between animal and bacterial viruses.

-Describe both lytic and lysogenic cycles.

-Explain the potential advantages of lysogeny versus lysis for a temperate virus

Answer 1

1.CHARACTERISTICS OF VIRUSES :-

1. They are recognised as responsible for a number of dreadful disease in human and plant.

2. They are obligate intracellular parasite .

3. Viruses are nucleo protein filterable agent as a nature of inert .

4. They are crystallisable and non living out side the body of host.

5. They contain a protein coat known as capsid.

6. They contain dna or rna simultaneously in the virion some variouses have spikes .

7 viruses are non livinv they are not made up of cell they do not have organells or cytoplasm they do not carry out metabolic process such as metabolish and homeostasis .

2. RECEPTORS FOR BACTERIAL VIRUSUS THATS BACTERIOPHAGE ARE :-

1. Bacterio phages they attached to specific receptor on the surface of bacteria this must include LIPOPOLYSACCHARIDE, TEICHOIC ACIDS ,PROTEINS ,SOMETIME FLAGELLA

So the host of bacterio phage recognised by attaching to specific cell surface receptors then by inject their dna or rna into the bacterium of cell .

3. PREVENSION FROM FOREIGN NUCEIC ACIDS:- So there is an adeptative immunsystem called crispr-cas through the in corporation small pices of dna from the infacting phage into bacterial genome.

When cells invading virus exposed to chemical they protect througb their dna receipe and inserting the wrong ammino acid into new protein .

4. REVERSE TRANSCRIPTASE:-

Ig is a bacially enzyme which generate complimentary dna from an rna template template this is known as reversed transcription viruses such as retro virus and retrotransposons there cdna integrated into the host genome from which host cells transcription helps the to make new RNA copies

There are several viruses that can use the resverse transcriptase which are named as HTVL this is human t-limpotroic virus that is type 1 and 2 and human immuno deficiency virus

A reverse transcripted enzyme thatwork on backward reaction from RNA to DNA .

QUESTION .7 . BACTERIAL AND ANIMAL VIRUSES DIFFERENCE :-

The main difference between them is that bacteria are the living cell that reproduce indenpendently that of virus are non living that require first cells for their replication.

Bactetia are much larger than viruses. Viruses need help of living cell in order to reproduce.

Bacteria infects eukaryotic. Viruses are pathogens infect prokaryotic and eukaryotic.

Q.8. LYTIC AND LYSOGENIC CYCLE :- The lytic cycle involves the reproduction of viruses using host cells for manufacturing of more viruses. Later viruses burst out of cells.

Lysogenic cycle they involves incorporation of viral genome into host cell genome.