1. Module 1Section 1.4VirusesAS Biology

2. Specification

3. There are many differentkinds of viruses The two you need toknow a bit of detail aboutare PHAGE and HIV(HumanImmunodeficiency Virus) You do not need to knowlife cycles! (so you canrelax)

4. Bacteriophage A bacteriophage (shortened to phage) is a virusthat infects and replicates within a particularspecies of bacteria They infect the bacteria by injecting their genome(which is either DNA or RNA based) into thecytoplasm of the bacterial cell This genome is then assimilated by the host, andthe viral genome is transcribed, viral proteins aremade and more virus particles are made

5. Bacteriophage StructureThe most well known isT4 BACTERIOPHAGEContains a DNAgenome bounded by aprotein coatUnder a microscopethey look like littlespaceships

6. HIV HIV, human immunodeficiency virus, is a diseasethe targets the immune system of the host Once the immune system is depleted enough andsecondary infections start to develop, peopleinfected with HIV are then said to have AIDS(Acquired ImmunoDeficiency Syndrome) There is currently no cure forHIV, however, combination drug treatments meanthat sufferers can lead full and normal lives

7. HIV StructureConsists of an RNAgenome bounded by aprotein coat andglycoprotein containinglipid bilayerA retrovirus; means ithas an RNA genomeSo it has the enzymeREVERSETRANSCRIPTASEpresent to allow DNA

8. The phage viral life cycle(simplified) You need to learn the very basicsfor how phage and HIV replicatewithin the host bacterial cell Phage invades the bacteria inwhich they replicate their geneticmaterial The host cell is hijacked toproduce viral particles that willform new viruses These new viruses leave the cell

9. The HIV virus attaches to T-helper cells where the virusincorporates its DNA into thecells genome This is done by REVERSETRANSCRIBING the viralRNA This leads to production ofnew viral particles and adestruction of white bloodThe HIV viral life cycle (simplified)