4.4 Bacteriophages Flashcards
What are bacteriophages typically known as?
phages
What are bacteriophages?
viruses that use bacteria as their hosts
What is transduction?
the genetic recombination of material in bacteria via phages
What is the most common bacteriophage?
bacteriophage T4
What does bacteriophage 4 use as its host?
E coli
What is the shape of the head of T4?
icosahedral head
Where is the DNA of T4 located and how many genes does it code for?
icosahedral head
150 genes
What does the tail structure of the T4 contain?
tube sheath that contains an inner spike and a base plate that contains several tail fibers
What helps the T4 virus bind to the bacteria cells surface?
base plate containing recognition signals
What happens once the T4 has bound itself to the host cell?
contraction of the outer sheath initiates the DNA in the head to be pushed through the cell membrane
What happens once the T4 DNA has entered the host cell?
host cell DNA is degraded and virus hijacks the cellular machinery to synthesize new viruses and assemble virions
How is the phage released from the host cell?
the host cell is lysed
What are virulent phages?
viruses that always lyse their bacterial hosts
What is a prophage?
virus that integrates its DNA into the bacterial chromosome
When are prophage viruses replicated within the bacterial cell?
when a stimulating event occurs; chemical or environmental stimuli
What are temperate phages?
viruses that are capable of either lysis or acting as a prophage
What determines how a temperate phage will act?
extra or intracellular conditions
How much bacteria in the ocean are destroyed by phages?
almost 40%
Why are humans, plants, and animals relatively safe from phages?
they grow and replicate by commandeering bacterial chromosomes
