Virus caq

🦠 Virus Created Tags Explain why viral RNA enter host cell nucleus For transcription where viral genome RNA is used as a template to synthesise the mRNA strands catalyses by viral RNA dependent RNA polymerase Which can be transported into cytosol as a template for translation of viral proteins which in turn acts as a template for replication of new viral RNA genome using host cells ribonucleotides and ATP which is abundant in nucleus How does new strains of virus arise Accumulation of mutation of the genome due to change in the ribonucleotide sequence known as antigenic drift caused by lack of proof reading ability of RNA-dependent RNA polymerase and high rate of replication of the virus giving rise to changes in the conformation of glycoproteins Formed when two or more strains infect the same host cell causing reassortment of different RNA segments to occur resulting in recombination of genetic material in a virion, giving rise to antigenic shift Why is HIV a retrovirus A retrovirus is a RNA virus that duplicate via reverse transcription in the host cell Using the RNA genome as a template, reverse transcriptase from the virus produce DNA from its RNA genome by complementary base pairing August 7 , 2025 1242 PM Virus 1

Why are viruses describe as obligate parasites An obligate parasite is an organism that cannot live independently of its host They require the host cell to complete their life cycle and reproduce Advantages of the lysogenic cycle Prophage can be replicated each time host cell/bacteria divides, allowing large number of viral particles to be assembled upon prophage induction Phage genome integrates itself into host cell/bacteria chromosome and becomes dormant as a prophage, allows prophage to survive for long periods when conditions for viral replication are unfavourable such as lack of nutrients When conditions change, prophage can be switched back to the lyric cycle and start reproducing again How does influenza enter a virus Haemagluttinin binds to sialic acid receptors on host cell membrane that are complementary in shape Virus is taken into host cell via receptor-mediated endocytosis Host cell membrane rearranges it cytoskeleton and extends in wards and invaginates and entire virus is enclosed within an endosome This endsosome will fuse with lysosome to form a phagolysosome, The resulting drop in pH causes Viral envelope to fusewith the membrane of the endosome To result in the release of nucleocapsid into the cytoplasm of the host cell and eventually viral RNA into cytosol How does influenza exist host cell Capsid proteins associate with ribonucleoprotein (viral proteins that associated with the Viral RNA near host plasma membrane Each new virus buds from host cell, Acquiring viral envelope from host plasma membrane which has neuraminidase and haemagglutin embedded Virus 2

Neuraminidiase cleaves sialic acid to release progeny virions from host cell surface Describe how different strains o