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Are viruses alive or
- –Are complex chemicals outside cells
- -Are living entities within live cells
Properties of viruses?
Obligated intracellular paracites; not composed of cells. Made of single nucleic acid (DNA or RNA) surround by protein coat. Multiply using cell synthetic machinery
Size of viruses?
- Diameter: 20-1000 nm
- lenght- up to 14,000 nm
Bacteriophages are what?
A bacterial virus; also called phages.
What is the viral protein coat called?
Protein subunits of the capsid are?
What is a virion?
complete, fully developed, infectious viral particle.
Viral nucleic acid (the genome) can be?
- DNA or RNA (never both)
- Non-segmented or segmented
- Double stranded/singled stranded
- - Long or curved rods/threads
- e.g. TMV, rabies virus, etc
Icosahedron structure (many sided)
Surrounds the capsid and derived from cellular membranes.
- have complex structures.
- ex. T-even phages, and poxviruses
Animal Viruses can be grown?
Lab animals, embryonated eggs and cell cultures
Cytopathic effect (CPE) is?
A visable effect on a host cell, caused by a virus that may result in host cell damage or death.
Primary Cell Line?
Cells with finite lifespan, cultured directly upon removal from animal
Continuous Cell Line?
Immoratalized cells; grow indefinitely in culture.
What are the steps in Viral Multiplication?
- 1) Attachment
- 2) Penetration
- 3) Uncoating
- 4) Biosynthesis
- 5) Maturation
- 6) Release
- Lytic and Lysogenic cylces are present depending on virus type.
- - only lytic cylce in T even phages
- - Both cycles in lambda phages
Ends with lysis and death of host cell
Phage DNA becomes inserted in host cell genome as prophage
The transfer of DNA from one cell to another by a bacteriphage.
Animal Virus Multiplication?
- DNA Viruses- multiply the nuclues; host enzyme transcribes viral DNA to give mRNA
- RNA Viruses- multiply in cytoplams
Why is viral cause of cancer difficult ot diagnose?
Viruses are difficult to see and many infect cell withoust causing caner. Cancer are not contagious and may not develop until long after viral infection is established
Viruses that cause cancers
What happens to cells when they are affected with cancer?
Loss of contact inhibiton, chromosome changes, tumor specific transplantation antigens, and T- antigens
Reamins for long period of time w/o disease. Infectious virus appear suddenly but usually not fatal.
occurs over long period of time. Infectious virus gradually builds up. Usually fatal.
are caused by infectious proteins called prions. Noraml cellular proin proteins is changed bye an abnormal scrapie protein.
Plant disease cause by naked RNA