Download Bacteriophage - Mrs. Yu`s Science Classes

Bacteriophage
Yvonne Lin AP Bio 2
a.k.a. Phages
Bacterial VIRUS
Attacks, infects, and replicates
within bacteria
Discovered by Frederick Twort
(Great Britain, 1915)
Species specific – named after
the group or species it infects
Structure of
Bacteriophage
Can be simple or complex
Size and shape vary
Basic features – capsid (head) +
tail
Capsid – made up of proteins that
protect DNA or RNA
Tail – hollow tube, nucleic acid
passes through to infect host cell
Lysogenic Cycle
Phage attaches to
host cell
Lytic cycle
Host cell reproduces
until triggered
Phage inserts DNA
into host cell
Phage DNA mixes
with host cell DNA
Lytic Cycle
Phage attaches to host cell
New phages attack
neighboring cells
Phage inserts its DNA into
host cell
Cell membrane breaks and
releases the new phages
Phage DNA takes over host
cell
Phage DNA starts to make
new phages in host cell
Applications
Phage therapy – treat bacterial infections that are resistant to
antibiotics by destroying them
Phage typing – identify pathogenic bacteria
Kill specific bacteria found in food (eg. Cheese)
Lambda phage
 Enterobacteria phage λ (coliphage λ)
 Infects bacteria Escherichia coli (E. coli)
 Most studied in genetic researches
 Used as a vector for the cloning of recombinant
DNA
Thank you for
listening
Sources:
http://textbookofbacteriology.net/phage.html
http://phages.org/bacteriophage/
http://www.cellsalive.com/phage.htm