18:bacteriophage Flashcards
What does phage replication require in a host?
energy production and nutrient acquisition
particle building blocks
protein synthesis
What Is step one of the lytic phage rep cycle?
phage attaches to host via receptors that bind bacterial surface molecules
attachment is specific, phage can bind to LPS, ompF, toiC, flagellar motor
to inject genome, phage must get through capsular polysaccharide by encoding a protein that degrades it
What Is step two of the lytic phage rep cycle?
phage deliver genome to host
phage T4 attaches to bacterium and uses pilus to inject DNA
genome is under pressure in capsized which drives the translocation into the host
What Is step three of the lytic phage rep cycle?
phage genome circularizes
What Is step four of the lytic phage rep cycle?
host cell machinery translates genome->phage proteins
phage genes encoded by host RNA polymerase
What are early genes
DNase degrades host genomic DNA, early genes transcribed and translated to protein, phage DNA undergoes rolling circle replication to make concatemer
What are late genes
capsid proteins self assemble to form empty particles
DNA packaging machine loads particle with replicated genome
make holins and lysins(holiness export lysin, lysin degrades cell wall)
What is lysogen?
a temperate phage can integrate its genome into the host genome to form a prophage, integrates via lambda phage integrate at atto site
What is generalized transduction?
can transfer any gene from donor to recipient
can be lysogenic or lytic
causes transducing particle,
What is speacilized transduction?
unique to lysogen bc requires lytic reactivation
phage integrates into host, stress induces lytic activation, host chromosome incorporated into phage particle
causes gene transfer
How do phages impact human health?
toxins and accessory genes
What is abhorrent excision?
exorcism error that results in host incorporation into phage
What is a specialized transducing particle?
host chromosome and prophage exported together
What is a transducing particle?
a genome with integrated phage genome that is excited, does not cause infection but may result in an aa change
What is a concatemer
multiple genomes rolled into one that can separate at a later time
