Virus Reproduction

1. Virus Reproduction

2. Lytic Life Cycle • 3 stages that include penetration, biosynthesis and lysis

3. Penetration • The lytic cycle begins when the virus attaches its tail fibers onto the surface of a bacterium, and injects its DNA into the cell. There is only a chance that the virus will come in contact with the right type of the host cell. In most cases, the virus will not completely enter the cell at all, but rather just their DNA. This process is known as infection as the virus is infecting the host cell. • If host is a bacteria, then the virus is a bacteriophage.

4. Biosynthesis • The virus' nucleic acid uses the host cell’s machinery to make large amounts of viral components. • Differences between DNA and RNA (retrovirus) • 1. Viral nucleic acids take control of the host cell and controls the host DNA, protein production and activity. • 2. Virus nucleic acids begins to be produced • 3. Virus structural proteins begin to be assembled (head and tail)

5. Lysis • New viruses are assemble from part made by the host cell • Virus produces an enzyme to break down cell wall, if needed • The cell eventually becomes filled with viruses (typically 100-200) and liquid, and bursts, or lyses; thus giving the lytic cycle its name. • The new viruses are then free to infect other cells.

7. Lysogenic Life Cycle • Penetration occurs the same • The virus nucleic acid is then combined with the host cell’s DNA and is then hidden for days, months or even years. • The virus DNA is then replicated and passed on anytime the host cell replicates • Each new daughter host cell is then infected with the virus DNA. The virus DNA is now called a prophage. • The prophage can exit the host DNA and enter the lytic life cycle at any time, this is usually caused by radiation or chemicals.

9. Virus Proteins • The proteins on the surface of viruses bind to the surface of the host cell. • These virus surface proteins can create new and different viruses

10. Virus Transmission • http://virustransmission.com/