Recap questions chapter 7b

1. Recap questions chapter 7b • What is autoimmunity? • You are blood type O- what blood type can you receive? • What blood type is the universal donor? • What must be given to transplant patients following their operation? Explain why.

2. Higher Human Biology Viruses Chapter 8

3. Viruses Learning Intentions: - What are viruses? - What is viral structure? - How do viruses reproduce? - What is a retrovirus?

4. What are viruses? • Living micro-organism (just!) • Only living characteristic is the fact that they reproduce • Form crystalline structures which is typical of non-living things • Obligate parasites because they need another living cell (host) in order to reproduce. • Host cell is destroyed therefore viruses always associated with disease • Viruses target specific cells - poliomyelitis virus targets nerve cells - hepatitis virus targets liver cells • Smaller than bacteria

5. What is the structure of a virus? • Viruses are not cells • Contain a nucleic acid (DNA or RNA) that carries the info required for multiplication • Surrounded by protein coat (capsid) • Many different types Herpes Simplex Virus The Cold Sore

6. Bacteriophage Virus

10. How do viruses reproduce? See cut out • A virus is inactive outside the host and can be dormant for a long time outside and inside the host cell • It depends on the host for: - nucleotides to make viral nucleic acids - amino acids to make viral protein - ATP for energy

11. History and Prevention of Viruses Small Pox Virus Small Pox blisters Cow Pox Virus Cow Pox blisters

12. History and Prevention of Viruses cont’d • Edward Jenner discovered that those who had suffered from cow pox were immune to small pox • This was the start of artificially acquired active immunity • Polio vaccine was the first to be used - contained dead virus at first - improved by using attenuated virus (nucleic acid destroyed by heat/chemical treatment) • Small pox now totally eradicated • Polio almost total eradication

13. What is a retrovirus? (The virus that is not so fashionable!) • Virus that contains RNA • Uses reverse transcription in order to produce viral RNA within host cell • Retrovirus contains enzyme reverse transcriptase which is injected into host cell along with the RNA • Virus escapes host by budding • Example Human Immunodeficiency Virus (HIV)

14. Human Immunodeficiency Virus

16. Lambda phage