Chapter 16 Genetic Variation Flashcards
how does asexual reproduction limit genetic mixing?
- no meiosis
- no gamete fusion
gene transfer that occures replication from parent cell to daughter cell
vertical gene transfer
gene transfer that is passed from one cell to another (doesnt involve replication)
Horizontal gene transfer
what are the mechanisms to aquire changes in genes for microbes?
- mutations
- Horizontal gene transfer between cells
mutation caused by error in replication or spontaneous chemical change is
Spontaneous mutation
mutation caused by a UV, Chemical, Radation exposure
Induced mutation
list the outword effects of changing the DNA sequence all the way to the phenotype
1) Change in DNA
2) Change in Codon
3) Change in amino acid
4) Change in Polypeptide
5) Change in phenotype
List possible ways of aquiring DNA in Horizontal gene(mechanisms)
1) conjugation
2) transformation
3) transduction
Horizontal gene transfer mechanism:
use physical contact to transfer DNA from one cell to anothe
conjugation
Horizontal gt mechanism:
pick up DNA from cell’s environment
Transformation
Horizontal gt mechanism:
infection by a lysogenic bacteriophage that carries DNA from previous host
transduction
in conjugation the cell produces a___ that makes connection with recipient cell.
pilus
in order for conjugation to occur ___ needs to be present on the ___ plasmid
- transfer and mobility genes example: tra/mob
- F plasmid
steps in conjugation (write these out)
1) cell makes contact with the pillus
2) the pillus shortens(making connection more stable
3) proteins form relaxisome/ bind DNA at origin of transfer
4) relaxisom cut 1 strand of DNA
5) relaxisom interacts with protein on pillus, pushing strand into opening
6) as the DNA enters the F factor DNA is replicated to form double stranded F factor.
structure that cuts single strand on F-plasmid
relaxisome
The F factor integrates with chromosome
high frequency of recombination (HFR)
where does the relaxisome make contact on plasmid?
origin of transfer
if the donor cell is and HFR strain is the whole chromosme likely to transfer ?
no
if the donor is an HFR is the recipient lickley to gain conjugation ability?
no
cells with mechanism to pick up DNA are called
naturally competent
in transformation, if the bacteria picks up a whole plasmid is it likely to be a stable or unseccessful transformation
- stable
- because the plasmid can replicate on its own
Bacteriophage type that infect and kill, do not transfer bacterial DNA
Lytic
Bacteriophage reproductive type
-viral DNA integrates with host DNA, may carry bacterial genes
Temperate
Bacteriophage reproductive cycle: viral DNA integrates with host DNA
Lysogenic cycle
the major turning point that differs between the lytic and lysogenic cycle
- lytic cycle- goes directly to synthesising new phages
- Lysogenic cycle- viral DNA is integrated into host chromosome first
in the lysogenic cycle,
what causes the dormant integrated viral DNA to be cut out and begin synthesis of bacterial phages (lytic cycle)
exposure to stress
