Plasmids and DNA transfer Flashcards
(29 cards)
describe virus structure
protein coat
single/double stranded DNA/RNA
describe how virus functions
only inside cells - not outsides
describe genomic organisation of parasitic eukarytoes of apicomplexa phylum
14 chromosomes, 1 apicoplast genome (similar to chloroplast), 1 mitochondrial genome
describe genomic organisation of bacteria
usually single circular chromosome - but can also be two circular chromosomes, or linear chromosomes, or one linear + one circular.
the smaller the genome, the more ______ in character an organism is
parasitic
do chromosomes contain genes essential for all conditions?
yes
do plasmids contain gens essential for all conditions? examples?
do plasmids replicate independently of host cell
no - however can regulate copy number, and resistance mechanisms etc
yes
can plasmids be circular or linear?
can chromosomes be circular or linear?
ye
Ye
what is copy number
average number of copies of a plasmid in a cell
how is copy number regulated
plasmids have genes that encode proteins which regulate the copy number
what are bacteriophages? describe their structure
viruses that infect bacteria
protein coat, genome, injecting apparatus
what are transposable elements?
mobile DNA that can move in and out of chromosome - insertion sequences, composite transposons, some bacteriophages
whats vartical transfer?
transfer of genetic material from parent to daughter - chromosomes, plasmid
what is horizonal transfer
transfer of genetic material from cell to unrelated cell - via transformation, conjugation, transduction,
describe transformation
competent bacteria take up DNA from environment
competency induced by chemicals/electroporation
why is plasmid DNA optimal in transformation
replicates independently
doesnt need to be taken up by chromosome
not easily degraded
describe conjucation process
pilus tip of F+ cell binds to receptor on surface of F- cell; pilus retracts to bring both cells together
conjugative bridge forms
plasmid nicked at origin of transfer, one strand goes to F- plasmid
DNA repairs itself
describe F factor
describe F plasmid
describe F+/F-
F factor = DNA encoding: sex pilus, origin of transfer, proteins required for DNA transfer
F plasmid contains F factor
F+ cell contains DNA with F factor; is the donor
F- cell contains DNA without F factor; is recipient
describe conjugation experiment
- E. coli require 5 amino acids to grow on a specific medium (doesn’t provide these aa’s). Strain A has genes encoding 2, strain B has 3. Therefore they can’t grow alone. Cultures of both strains combined, conjugation occurred, some growth occurred.
- When this experiment was replicated but strains A and B were separated by a filture, no growth occurred – hence via conjugation
describe transduction
transfer viva bacteriophages
two ways bacteriophages replicate?
lytic cycle
lysogenic cycle
describe lytic cycle
bacteriophage injects DNA into cell
bacteriophage, and DNA within them, replicates
cell lyses, releasing bacteriophages iwth DNA
describe lysogenic cycle
bacteriophage injects DNA
DNA integrates into chromosome
everything replicates
what happened in transduction experiment?
occurred even when there was a filter - bacteriophages could pass the filter.
