Recombination

Question 1

What is recombination?

Answer 1

Recombination is the physical exchange of DNA sequences between different molecules OR any exchange between (or integration of) one DNA molecule and another

Question 2

What are the three types of recombination?

Answer 2

Homologous recombination

Non-homologous recombination

Site-specific recombination

Question 3

What is homologous recombination?

Answer 3

The exchange of DNA from one DNA duplex to a second DNA duplex with very similar or identical sequence. It is used in DNA damage repair and meiosis

Question 4

What is the basic mechanism for homologous recombination?

Answered simply - read notes for more info

Answer 4

• Double strand breaks in one of a pair of homologous DNA duplexes
• Exonuclease degrades the 5’ ends of the cut DNA to produce 3’ single strand overhangs
• Strand invasion occurs
• DNA synthesis of 3’ end using undamaged strand of invaded DNA as template
• Displaced strand anneals (from original DSB)
• DNA synthesis to extend both 3’ ends
• Branch migration of displaced strand displaces 5’ end of original damaged DNA resulting in two interconnected molecules with nicks in each
• DNA ligase fixes the nicks
• DNA is cut and ligated to separate the two molecules