Viruses Where do they fit?

What are Viruses? bacteria and viruses cause many diseases for all kingdoms; however, bacteria are classified as living while viruses are not. Why?? – viruses: have no cellular structure, cytoplasm, organelles, or cell membrane, and they do not carry out respiration or other life processes. they consist of strands of DNA/RNA surrounded by a protective protein coat called a capsid

there are 160 major groups which differ in size and shape ( Fig page 122 ) viruses do multiply but not on their own. They infect other cells and depend on the metabolism of the ‘host’ cell to multiply the viral information refer to the Life Cycle of the “T4" virus ( Fig.4.21 page 123 )

Viral Reproduction There are 2 well identified routes that a viral unit can enter a cell and reproduce. There are 2 well identified routes that a viral unit can enter a cell and reproduce. Entry Entry 1. A capsid can bind to a specific region of the host cell and inject the viral DNA/RNA into the cell. 1. A capsid can bind to a specific region of the host cell and inject the viral DNA/RNA into the cell. 2. A enveloped virus will bind to the host cells’ membrane and be taken into the cell as a vacuole. 2. A enveloped virus will bind to the host cells’ membrane and be taken into the cell as a vacuole.

Types of Reproduction Lytic Cycle : Lytic Cycle : virus injects its’ viral DNA/RNA into the host virus injects its’ viral DNA/RNA into the host virus takes over the cells’ metabolism and reproductive organelles creating viral DNA/RNA and capsids and assembling them together virus takes over the cells’ metabolism and reproductive organelles creating viral DNA/RNA and capsids and assembling them together the host cell eventually bursts open releasing hundreds of newly created viruses to spread, killing the original host. the host cell eventually bursts open releasing hundreds of newly created viruses to spread, killing the original host. Reproduction movie Reproduction movie Reproduction movie Reproduction movie

Retrovirus and Provirus (HIV) Retrovirus – a retrovirus is a virus that does not kill the host immediately (if ever) Retrovirus – a retrovirus is a virus that does not kill the host immediately (if ever) The virus contains reverse transcriptase (enzyme) which converts RNA (viral) into DNA that replicates as the cell carries out it’s normal cellular division. The virus contains reverse transcriptase (enzyme) which converts RNA (viral) into DNA that replicates as the cell carries out it’s normal cellular division. Provirus – splices into the hosts’ genome (DNA), lying in wait, being passed on to daughter cells during normal cellular division. An unknown trigger causes the viral DNA to come out of the host’s DNA and then go through the lytic cycle. Provirus – splices into the hosts’ genome (DNA), lying in wait, being passed on to daughter cells during normal cellular division. An unknown trigger causes the viral DNA to come out of the host’s DNA and then go through the lytic cycle.

Viruses and Biotechnology Viruses can be very helpful in producing numerous copies of a desired gene. Viruses can be very helpful in producing numerous copies of a desired gene. A ‘gene’ can be spliced into the viral DNA (recombinant DNA) and allowed to then infect a cell to create the desired gene product. A ‘gene’ can be spliced into the viral DNA (recombinant DNA) and allowed to then infect a cell to create the desired gene product. HIV HIV HIV