Question

1. Upon virus break-up in a host cell, in order for the virus to complete its life cycle, negative polarity RNA molecules must be...

2.The two major tasks that a typical virus must complete upon infecting its host are: 3. When naked DNA is injected into humans, most of the DNA: 4. what happens briefly in the life cycle of the typical togavirus?

Answer 1

1.) Upon virus break-up in a hostcell , in order for the virus to complete its life cycle, negative polarity RNA molecules must be converted to positive polarity RNA molecule by an RNA dependent RNA polymerase because negative polarity molecule is not infectious by itself but a positive sense RNA virus can infect directly.There is a need to infect host cell as virus can't complete its life cycle without infecting cell. So it must be converted into positive polarity molecule.

2.)The two major tasks that a typical virus must complete upon infecting its host are-

(a) It must enter into the host cell.

(b) It must suppress the gene expression of host cell.

4.) The Togaviridae family of Togavirus belong to group IV of the Baltimore classification of viruses. Its genome is linear, non-segmented, single-stranded, positive sense RNA that is 10,000–12,000 nucleotides long.

Entry into the host cell is achieved by attachment and endocytosis by the host cell.After attachment and entry into the cell virus starts replication and gene expression in the cytoplasm of host.Its replication follows the positive stranded RNA virus replication model. Its DNA Suppresses the gene expression of host DNA. It transcripts by the same transcription model(Positive stranded RNA virus transcription model).Translation of RNA takes place by virul infection and suppression of termination. Newly formed protiens assembles at the cell surface where the virus buds from the cell, acquiring the envelope. After that virus breaks the host cell and infects new cell.