Horizontal Transfer Flashcards
(24 cards)
what induces chromosomal rearrangements?
radiation exposure
how will two identical genomes appear in a dotplot?
single diagonal line
what is a consensus sequence?
most recurring base at each position
what is sequence alignment?
the distance/divergence between sequences
how are phylogenetic trees constructed?
aligning the sequence of conserved genes
observing presence/absence of traits
what is multi locus sequence typing?
multigene tree obtained by combining multiple housekeeping genes in a tree
what applications does multi locus sequence typing MLST have?
clinical microbiology - differentiate between pathogen strains
to track virulent strains distribution
what does genome fingerprinting allow?
the detection of polymorphism across species
how is genome fingerprinting carried out?
- ribotyping
- rep PCR
- AFLP
What is ribotyping?
a restriction digest of total genomic DNA - generates fragments separated by gel electrophoresis
band hybridisation generates a fingerprint
what is rep PCR?
primers on conserved repeats to amplify DNA between these repeats
what is AFLP?
digestion of genomic DNA and PCR amplification
what are the advantages and disadvantages of whole genome sequencing?
costly and time consuming but highest level of resolution
what are the steps in gene transfer in bacteria?
- transformation
- conjugation
- transduction
what is transformation in the context of gene transfer?
DNA released from one cell taken up by another cell
most species not capable
what species are capable of transformation?
bacillus subtilis, strep pneumonia
how can transformation be forced?
heat or electric shock
how does conjugation occur in gene transfer?
DNA synthesized by rolling circle replication
contact established
single strand nick by tral in plasmid
second DNA strand synthesised in donor cells and recipient cells
what is the nicking enzyme in conjugation and what encodes it?
Tral - tra operon
what is tral?
nicking enzyme in conjugation. also a helicase that unwinds DNA for transfer
what is transduction in gene transfer?
DNA transfer mediated by a virus eg bacteriophage
what is generalised transduction?
any gene on donor chromosome can be transferred
what is the difference between the lytic and the lysogenic cycle?
lytic results in lysis of infected cell
lysogenic integrates the viral DNA into host genome
what is specialised transduction?
transfer is selective and only restricted to small region of the bacterial chromosome
