Replicação na presença de erros

Recombination at the Molecular Level

• Breakage and joining also directed by enzymes.

• Homologous recombination occurs during synapsis in meiosis I, general recombination in bacteria, and viral genetic exchange.

• Molecular mechanism proposed by Holliday and Whitehouse (1964).

• Depends on complementary base pairing.

RecA protein-mediated DNA synapsisRec A has multiple DNA binding sites, hence can hold a single strand and a double helix together

Rec A is also a DNA-dependent ATPase

RecombinationalDNA

repair

Site-specificrecombination

Integração ou excisão de um bacteriofago

Replicative transposition – the element moves a copy of itself to a new site via a DNA intermediate

Conservative transposition – the element itself moves from the donor site into the target site

Retrotransposition – the element makes na RNA copy of itself which is reversed transcribed into a DNA which is then inserted

When IS elements get it together:composite transposons

Two IS elements flank an antibiotic resistance gene

Tn10 (E.coli)