Kategorier: Alle - attachment - release

av Jenny Doriot 16 år siden

1500

Multiplication of Bacteriophages

Bacteriophages, viruses that infect bacteria, follow two primary cycles during their multiplication: the lytic and lysogenic cycles. In the lytic cycle, the process begins with the attachment of the bacteriophage to the bacterial cell, followed by the penetration where the phage DNA is injected into the host.

Multiplication of Bacteriophages

Multiplication of Bacteriophages

Lysogenic Cycle

Important Results
3. specialized transduction: phage DNA and Bacterium DNA both in capsid
2. phage conversion: host cell may exhibit new properties

Vibrio cholerae

Clostridium botulinum

Corynebacterium diptheriae

1. cells are immune to reinfection
5. popping out of phage DNA and lytic cycle is started
4b. replicates the prophage DNA...prophage remains latent w/in the progeny cells
3b. circle can recombine and become part of bacterial DNA
every time bacterial DNA replicates so does the phage DNA
phage is now called prophage
4a. new phages produced and lysis occurs
3a. circle can multiply and transcribe
2. linear phage DNA forms a circle
1. penetration into E. coli cell
phage remains inactive
does not cause lysis and death of host cell

Lytic Cycle

5. Release: virions released from host cell
4. Maturation: bacteriophage DNA and capsids are assembled into complete virions
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
2. Penetration: Bacteriophage DNA injected into bacterium
capsid remains outside
tail releases enzyme which breaks down portion of cell wall--phage lysozyme
1. Attachment: attachment site on virus fuses with receptor on bacterial cell
ends with lysis and death of host cell