DNA Replication, Repair 3

Question 1

What is the protein complex that forms during Meiotic Recombination?

Answer 1

Spo 11 and Mre 11

5’ ends are cut

Nuclease processing

Rad51/RecA catalyze a exchange of

Release of invading strand/DNA synthesis and ligation or double Holliday Junction

Question 2

What enzyme processes Holliday Junctions?

Answer 2

Endonuclease RuvC with two outcomes

Crossing Over must be cut in opposite directions

Gene Conversion must be cut in same way

Question 3

Explain Branch Migration?

Answer 3

Process of migration in the Holliday Junction.

Invading strand creates a branch point.

Can increase/decrease heteroduplex DNA

Energy driven annealing favors more heteroduplex DNA/

Question 4

How do Gene Conversion occur?

Answer 4

Repair of mismatches mistakes during synthesis of heteroduplex.

One allele is lost due to this and the other is duplicated

Results in unequal amount of genetic material being passed.

Question 5

What are the types of Recombination?

Answer 5

DNA-only transpospsons

Retrovirus-like retro transposons

Nonretroviral retrotransposons

Question 6

What is the enzyme used by transposons?

Answer 6

They in-code their own transposase.

Question 7

What enzymes are used by Retroviaral-like retrotransposons?

Answer 7

Reverse transcriptase and Integrase

Question 8

What enzymes are used by Nonretroviral retrotransposons?

Answer 8

Reverse transcriptase and endonuclease

Question 9

Explain Retrovirus-like Transposons?

Answer 9

Not site specific

Integrase inserts

Question 10

Explain Nonretroviral Transposons?

Answer 10

Require reverse transcriptase

Need endonucleas to make cut at random

Turns RNA into DNA and then inserts

Requires other transposase

Question 11

Explain DNA Transposons?

Answer 11

Only moves as DNA

Responsible for antibiotic resistance.

Move in and out of DNA through cut-and-paste or replication transposition.

Transposome leads to central intermediate.

Attacks target/staggered break

Question 12

How does conservative Site specific recombination differ from transposition?

Answer 12

Need special sites on each DNA that serve as recognition sites for recombinase

Form high energy bond

Question 13

What is distinguishable about the “site” in site specific conservation/recombination?

Answer 13

Not always homologous to host cell.

Integration, Exicision, or Inversion

Depending how certain sequences are aligned.

Need special sequences in the donor chromosome

Form high energy bonds to complete.

Question 14

What occurs in doubled strand breaks during Meiosis.

Answer 14

Strand Invasion and Holliday Junction

Crossing may or may not occur