Multiplication of Bacteriophages

ends with lysis and death of host cell

1. Attachment: attachment site on virus fuses with receptor on bacterial cell

2. Penetration: Bacteriophage DNA injected into bacterium

tail releases enzyme which breaks down portion of cell wall--phage lysozyme

capsid remains outside

3. Biosynthesis: once bacteriophage DNA reaches cytoplasm of host cell, biosynthesis of viral nucleic acid and proteins occur

eclipse period: when infection virions are not present

4. Maturation: bacteriophage DNA and capsids are assembled into complete virions

5. Release: virions released from host cell

does not cause lysis and death of host cell

phage remains inactive

1. penetration into E. coli cell

2. linear phage DNA forms a circle

3a. circle can multiply and transcribe

4a. new phages produced and lysis occurs

3b. circle can recombine and become part of bacterial DNA

phage is now called prophage

every time bacterial DNA replicates so does the phage DNA

4b. replicates the prophage DNA...prophage remains latent w/in the progeny cells

5. popping out of phage DNA and lytic cycle is started

Important Results

1. cells are immune to reinfection

2. phage conversion: host cell may exhibit new properties

Corynebacterium diptheriae

Clostridium botulinum

Vibrio cholerae

3. specialized transduction: phage DNA and Bacterium DNA both in capsid