Lyctic vs lysogenic Flashcards
Multiplication of Bacteriophages: Lytic cycle
Phage multiply rapidly and cause cell to burst (“lysis”)
- Phage causes death of the host cell
T-Even Bacteriophages: Steps of The Lytic Cycle
Attachment:
Penetration
Biosynthesis
Maturation
Release
Attachment
phage attaches by the tail fibers to the host cell
Penetration
phage lysozyme opens the cell wall; tail sheath contracts to force the tail core and DNA into the cell
Biosynthesis
production of phage DNA and proteins
Maturation
assembly of phage particles
Release:
phage lysozyme breaks the cell wall
Multiplication of Bacteriophages:Lysogenic cycle
Phage insert DNA into host’s DNA where it remains dormant for long time.
Phage conversion
Specialized transduction
Viral DNA ‘hiding’ in the host cell’s DNA is called a “
lysogen”
Lysogeny:The Silent Virus Infection
Temperate phages
Undergo adsorption and penetration
Do not undergo replication or release immediately
Viral DNA enters an inactive prophage state:
Inserted into bacterial chromosome
Copied during normal bacterial cell division
Lysogeny: a condition in which the host chromosome carries viral DNA
Induction:
virus in a lysogenic cell becomes activated and progresses directly into viral replication
Three results of lysogeny
- Lysogenic cells immune to re-infection by same phage
- Phage conversion: host cell has new properties
3.Specialized transduction
The Danger of Lysogeny in Human Disease
Occasionally phage genes in the bacterial chromosome cause the production of toxins or enzymes that cause pathology in the human.
when a bacterium acquires a new trait from its temperate phage
Lysogenic conversion
ex. Clostridium botulinum – botulinum toxin
