DNA repair Flashcards

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1
Q

What does photolyase do? What does it require to function? What organisms have it?

A

Breaks photodimers. It requires light to function and is found in bacteria, plants, fungi, and some animals

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2
Q

What does alkyltransferase do?

A

Removes alkyl groups and repairs damage from alkylating agents

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3
Q

What is the base excision repair pathway? What does it target?

A

It cuts a single base that doesn’t distort the double helix

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4
Q

What enzymes are used in the base excision repair pathway?

A

DNA N-glycosylases

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5
Q

What are the 4 steps in the base excision repair pathway?

A
  1. DNA glycosylase removes the damaged base by cutting the bond between it and the sugar
  2. AP endonuclease makes a cut 5’ to the removed base
  3. DNA is removed and replaced
  4. DNA ligase seals the break
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6
Q

What is the nucleotide excision repair pathway? What does it repair?

A

Removes a section of DNA around a damaged area. Targets photodimers, areas with lots of damaged bases, bulky DNA damage that blocks transcription

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7
Q

What enzymes are required for the nucleotide excision repair pathway? What signals them to come fix a problem?

A

Uvr proteins. Has transcription coupled repair, RNA polymerase signals Uvr proteins to come if it gets stick

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8
Q

What are the 5 steps in the nucleotide excision repair pathway?

A
  1. Transcription is blocked and the damage is recognized
  2. Multi protein complex is assembled
  3. Area around the damaged nucleotides is cut by Uvr C and removed by Uvr D
  4. DNA polymerase fills in the gap
  5. Sealed by DNA ligase
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9
Q

What are the proteins involved in mismatch repair? What are their functions?

A

MutS, MutH, and MutU
MutS recognizes a mismatched pair and recruits MutH. They cut out an area around the mismatch and MutU removes it and DNA polymerase fills in the gap

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10
Q

What would cause DNA to not be repaired?

A

There’s too much damage for the enzymes to keep up with

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