bacterial genetics. gram-positive bacteria transform dna using a transformasome complex. figure 9.1
TRANSCRIPT
Bacterial genetics
• Gram-positive bacteria transform DNA using a transformasome complex.
Figure 9.1
Gene Transfer by Conjugation• Conjugation is the transfer of DNA from one
bacterium to another, following cell-to-cell contact.
- It is typically initiated by a special pilus protruding from the donor cell.
Figure 9.2
Figure 9.3
Figure 9.4
• An integrated F-factor can excise from the chromosome.
• - Aberrant excision results in an F factor′ or F ′plasmid, which carries chromosomal genes.
Figure 9.5
Hfr leu+ thr+pro+lac+bio+Sms XF- leu- thr-pro-lac-bio-SmR
What medium should we use to obtain1. leu+ transconjugants2. pro+ transconjugants3. lac+ transconjugants
Hfr leu+ thr+pro+lac+bio+Sms XF- leu- thr-pro-lac-bio-SmR
1. leu+ transconjugants2. pro+ transconjugants3. lac+ transconjugants
What are the map positions of leu, pro, and lac?
time No.of colonies on medium1 2 3
0 0 0 0
5 0 0 0
10 8 0 0
15 28 6 1
20 48 16 6
25 68 26 11
0
1020
3040
50
6070
80
1 2 3 4 5 6
time
no
.co
lon
ies
Figure 9.7
Generalized Transduction
Figure 9.9
Figure 9.8 Specialized Transduction
Figure 9.14
Generalized Recombination
Figure 9.15
Figure 9.30
• IS elements transfer by one of 2 mechanisms:• - Replicative or nonreplicative transposition
Mobile Genetic Elements
Figure 9.31