Viruses For EOC Review

IV.Preventing Bacterial Disease 1. Vaccine- A preparation of a weakened or killed pathogen, such as a bacterium or virus. Body produces antibodies. 2. Antibiotics- compounds that block the growth and reproduction of bacteria. 1. A substance, such as penicillin, that is capable of destroying or weakening certain microorganisms, especially bacteria or fungi, that cause infections or infectious diseases. Antibiotics are usually produced by or synthesized from other microorganisms, such as molds.

V.Viruses 1. Structure a) Composed of Nucleic Acids  DNA or RNA– not both b) Surrounded by a capsid (protein coat) c) Fibers/ Proteins for attachment to host cell d) Can be seen with electron microscope only

V.Viruses d) Varies greatly in size & can only be seen with electron microscope

V.Viruses 2. Reproduction- Must infect a host in order to reproduce a) Attach to host cell b) Insert DNA or RNA c) Use machinery and resources of host cell to produce more virus copies d) Highly specific  Virus types only can infect certain hosts  Ex: bacteriophage only can infect bacteria

VI.Types of Virus Replication 1. Lytic Cycle a) Infection/ attachment Injects DNA or RNA into host b) Growth Virus DNA shuts down normal cell activities to make copies of itself c) Replication Uses resources of host to make copies d) Cell lysis Infected host cell bursts and releases new virus copies to that will infect other cells

What is happening in each step?

VI.Types of Virus Replication 2. Lysogenic Cycle a) Virus integrates DNA into host Virus remains inactive Does not lyse host cell immediately b) Prophage- viral DNA embedded into host DNA c) When conditions change virus can switch to lytic infection

Are viruses alive??