Genetic Recombination and Genetic Engineering

Chapter 14
Genetic Recombination and
Genetic Engineering
The biochemistry and molecular
biology department of CMU

Section 1
DNA Recombination

DNA recombination
•
Homologous Recombination
•
Conjugation
•
Transformation
•
Transduction
•
Site-specific Recombination
•
Transposition

　
§1.1 homologous Recombination
•
Homologous recombination occurs between identical or nearly
identical sequences. It is also called general recombination.

DNA invading

(recA)
Branch
migration
(recA)
DNA
ligase
5´
3´
5´
3´
5´
3´
5´3´
5´ 3´
5´ 3´
5´3´
5´3´
5´ 3´
5´ 3´
5´3´
5´3´
5´
3´
5´ 3´
5´ 3´
5´3´
5´3´
3´5´
5´ 3´
5´3´

5´
3´
Holiday intermediate
5´ 3´
5´ 3´
5´3´
5´
3´
endonuclease
(recBCD)
endonuclease
(recBCD)

5´ 3´
5´ 3´
5´3´
5´
3´
5´
3´
5´
3´
5´
3´
5´3´
Holliday intermediate

5´
3´
5´

5´
5´
3´
3´
3´
5´
5´
5´
5´
3´
3´
3´
3´
5´
3´
5´
5´
5´
3´
3´
3´
5´
5´
5´
5´
3´
3´
3´
3´
5´

3´
5´
5´
5´
3´
3´
3´

endonuclease
(ruvC)

endonuclease
(ruvC)
DNA ligase
DNA ligase
patch
recombinant
splice
recombinant

•
Bacterial Conjugation has been defined as the transmission of
genetic information from a donor bacterium to a recipient cell
through cell-to-cell contact.
§1.2 Conjugation

　
Conjugation process

　

Conjugation process

　
Conjugation process

　
§1.3 Transformation

Introduction of an exogenous
DNA into a cell, causing the cell to
acquire a new phenotype.

　
DNA
Transformation

　
Transformation experiment of
Streptococcus pneumoniae

　
§1.4 Transduction
•
Transduction is the transfer of DNA fragments from one
bacterium to another bacterium by a bacteriophage.

　
Transduction

　

　

•
Site-specific recombination occurs at a
specific DNA sequence.
•
The first example was found in the
integration between λ DNA and E. coli
DNA.
§1.5 Site-specific Recombination

λDNA integration


P
1
H
1
P
2
hin
H
2
×è¶ô»ùÒò
DNA
P
1
H
1

hin
H
2
×è¶ô»ùÒò
H segment H
1
flagellin
H
2
flagellin
repressor
P
2
P
2
hix hix
Phase variation of Salmonella
typhimurium flagella
Hin
rH1
rH1



Recombination activating gene enzyme
(RAG1 and RAG2)
CACAGTG (12/23) ACAAAAACC
GTGTCAC TGTTTTTGG
RSS
Recombination signal sequence (RSS)