DOH133 Lecture Notes - Lecture 1: Prophage, Animal Virus, Chromosome
List 5 differences between viruses and bacteria
1. Bacteria have ribosomes, viruses do not
2. Bacteria have a cell wall, viruses have a protein coat
3. Bacteria are larger (1000nm), Viruses (20-400nm)
4. Bacteria are unicellular, Viruses no cell
5. Bacteria are living organisms, viruses alternate between living and non-living
Give the name of a Viral Species
Human Herpes Virus
Family = -Viridae – Herpesviridae
Genus = -Virus – Herpesvirus
Species = common name – Human Herpes Virus
List three techniques used to identify viruses
1. Cytopathic effects
- The visible effects of viruses on host cells Can be cytocydal or non-cytocidal
effects
2. Serological tests
- Detect antibodies against viruses in a patient
3. Nucleic acid amplification
- Detection by PCR amplification with a specific DNA probe; possibly after
RT-PCR for RNA viruses
Describe how bacteriophage are cultured
A bacterial lawn is spread on an agar plate with bacteria that are infected with virus. The
clear spots in the lawn are called plaques. A plaque is a bacterial colony that has been
infected and lysed (broken- open) by its viral infection. Interestingly, the way that
bacteriophage can kill bacteria makes them an alternative to antibiotics.
Describe the lytic cycle of T-even bacteriophages
1. Attachment: Phage attaches by tail fibres to host cell
2. Penetration: phage-encoded lysozyme opens cell wall; tail sheath contracts to force
tail core
and DNA into cell
3. Biosynthesis: Production of phage DNA and proteins
4. Maturation: Assembly of phage particles
5. Release: Phage encoded lysozyme breaks cell wall
Document Summary
Species = common name human herpes virus. List three techniques used to identify viruses: cytopathic effects. The visible effects of viruses on host cells can be cytocydal or non-cytocidal effects: serological tests. Detect antibodies against viruses in a patient: nucleic acid amplification. Detection by pcr amplification with a specific dna probe; possibly after. A bacterial lawn is spread on an agar plate with bacteria that are infected with virus. The clear spots in the lawn are called plaques. A plaque is a bacterial colony that has been infected and lysed (broken- open) by its viral infection. Interestingly, the way that bacteriophage can kill bacteria makes them an alternative to antibiotics. Animal viruses differ from phage"s in their mechanism of entering the host cell. Also, once the virus is inside, the synthesis and assembly of the new viral components are somewhat different, partly because of the differences between prokaryotic cells and eukaryotic cells.
