Lab 26, lab 30.1 Flashcards
Bacteriophage infection pathways
lysis and lysogeny
growing phages
plaques and cloudy vs clear
(PFU)/ml meaning
Plaque- forming units
Titer=
of plaques * 1 / dilution factor
Viruses are:
unicellular, obligate intercellular parasites
Viruses contain:
DNA or RNA which is their genetic material
Genetic material is enclosed in a protein coat called
capsid
the capsid may also contain a ____ or a ____
tail or a body through which genetic material is injected into the host.
At the end of a virus there are tail fibers present which have the ability to attach to specific sites which are called
receptors
Receptors are generally
proteins or glycoproteins
viruses that infect bacteria are called
bacteriophage or simple phage ( phagein; to eat)
phage which affects e.coli is called
coliphages
Lytic phage:
causes lysis of the cell:
1. takes over the replicative machinery of the cell
2. uses those components to make a new phage -> mature phages
3. cell resources have been depleted
4. host cell burst
5. phage particles are released to infect bacterial cells
lysogeny
Mostly follow the lysis cycle
Some do not form stable relationships with the host cell
phage incorporates into the genome of the host at a specific site
Bacteriophage infections can be visualized by the
formation of plaques
plaques are;
zones of clearing in bacterial lawns
Lytic phages produce _____ plaques
why?
clear
due to the killing of the cells in the zone
lysogenic phages give ____ plaques
why?
cloudy
growth of lysogens within the zone
Plaques can be used to;
count the number of bacteriophage
the number of bacteriophage in a sample is known as
titer
Starch is a _____ _____ produced by _____
a complex carbohydrate , plants
amylases:
enzymes which break down amylose and amylopectin to maltose, glucose and dextrins
An indicator used is
iodine
Eaten starch-clear area- no more starch
iodine will not turn the area black
starch has not been metabolized
iodine will turn black
