Warm Up Monday, March 18, 2013 Which process copies a strand of DNA (DNA to DNA)?

Virus Notes

Objectives 1)List the major components of a virus. 2) List the steps involved in virus replication. 3) Describe a real world scenario in which viruses have had a negative impact on human lives.

Viruses NOT living organisms Infects host cells Inject their genetic material into host Needs host in order to replicate

Parasites = depend entirely upon another living organism to survive, harming organism in process Viruses = parasites Take advantage of hosts respiration, nutrition, & all other functions

Virus Genetics Composed of DNA or RNA core –Surrounded by protein coat Simplest: few genes Most complex: >100 genes

Capsid = Protein coat that surrounds DNA/RNA Enable virus to enter host cell –Bind to receptors on surface of cell –“Trick” cell into letting it in –Once inside, viral genes expressed

Cold Viruses

Flu Virus

Viruses Specific Bind to specific proteins on host cell’s surface Why does it matter? –Infect specific cells –Infect specific organisms Example: –HIV infects humans –Parvovirus infects dogs, wolves, & foxes

Bacteriophage = virus that infects a bacterial cell Structure: 1)Head = contains DNA 2)Neck 3)Collar 4)Sheath 5)Tail Fiber 6)Base Plate

Lytic Infection 1.Virus enters cell 2.Virus copies itself 3.Cell bursts

Lytic Cycle 5 Stages: 1)Attachment (a) - virus attaches itself to host cell 2)Injection (a & b) - virus inserts its genetic material into host cell 3)Integration (c) - genetic material tells the cell what to do 4)Replication (d) - host cell builds parts of virus Assembly (d) - cell assembles replicated parts into progeny viruses 5) Lysis (e)- cell breaks open & ea. replicated virus can infect other cells

Lysogenic Cycle Latent period extends cycle Viral DNA becomes part of host chromosome for a time

Lysogenic Infection 1.Virus enters (a-1) 2.Integration: Virus integrates viral DNA w/ host cell DNA (a-2) 3.Viral DNA is replicated (when host cell replicates DNA) (a-3) 4.Host cell completes mitosis & makes other cells infected w/ virus (a-4) ***Difference: Host cell does NOT burst!!! (b)***

Prophage Viral DNA that’s embedded in the host’s chromosome (DNA)

Retrovirus = contain RNA as the hereditary material in place of the more common DNA Genetic information copied backward –RNA to DNA (usually other way) May remain dormant & wait for right conditions to become active –Dormant = not active (like sleeping)

Retrovirus Example: –virus that causes AIDS –(acquired immune deficiency syndrome)

Viral Diseases CanNOT be treated w/ antibiotices Must PREVENT infection –Vaccinations –Stopping spread

Other Viral Diseases Chicken Pox –Symptoms: fever and weakness, red, itchy rash –Spread By: contact w/ rash –Prevention: Vaccine

Other Viral Diseases Measles –Symptoms: High fever, sore throat, cough, rash, sneezing, swollen eyelids, whiter spots on cheek lining –Spread By: Droplet inhalation –Prevention: Vaccine

Other Viral Diseases West Nile –Symptoms: Fever, headache, body ache- –Spread By: Bite from an infected mosquito –Prevention: Mosquito repellant, avoid going outside at dawn & dusk, avoid standing water

AVID Thinking Strategies WANTED Virus Poster (2 colors) Include: –The words “WANTED” at the top –Virus name –Drawing of virus or picture that depicts aspect of virus life cycle (Ex: mosquito for west nile) –Symptoms that are seen in infected host –How virus spread –Prevention/Treatment

Warm Up Tuesday, March 19, 2013 Which process creates a strand of RNA (DNA to RNA)?

Germ Warfare Reading & Summaries