viruses

requiree a living host cell in order to muliply

they cant reproduce on their own

either DNA or RNA covered by a protien coat

inside living cells by using the synthesizing metabolic machinery of a cell to transfer the viral nucleic acid to other cells

range of cells/tissues viruses can infect

• by a receptor found on the cell surface
• viruses can only infect a specific type of tissue within a host cell

• by electron microscopy. 20 to 100nm
• cannot be seen under a microscope.

• antiviral protien
• alpha, beta, gamma

• a virus infected cell and migrate to uninfecceted cells taht then produce antivral protiens
• host cell specific

• attachment
• penetration
• biosynthesis
• maturation
• release

bateriophage attaches to cell wall

phage makes opening in cell and injects DNA

phage DNA directs synthesis of viral protien and nucleic acid

viral compnents are assembed into virons

host cell dies and virions are released into surrounding medium

• instead of biosynthesis maturation and relase
• nucleic acid is integrated into genome becomeing a prophage

inserted phage DNA O

• attachment- uses receptors on cell sufaces often using spikes on a virus
• penetration- whole virus enerts cell via endocytosis
• uncoating- virus capsid is removed
• biosynthesis- transcription produce virus enzymes, viral nucleic acid, and capsid protiens
• maturation- virus particles are assembled
• release- virus particles are exposed

• produce reverse transcriptase to make cDNA
• dna then directs synethesis of viral components
• attachment
• entry and uncoating
• RNA replication by RNA polymerase
• translation and synthesis of viral protiens
• maturation and release

• first identified in chickens
• genes derviced originally from host
• cancer causing process- transformation