Mutations and DNA Repair — Flashcards

Flashcard 1: Mitochondrial DNA has a _____ mutation rate than that of nuclear DNA

Answer: higher (higher/lower)

Flashcard 2: _____ radiation results in the formation of double-stranded breaks in DNA and hydroxyl free radicals which damage DNA

Answer: Ionizing

Flashcard 3: Which DNA polymerases are primarily responsible for DNA repair in prokaryotes and eukaryotes?

Answer: Prokaryotes: **DNA polymerase I** Eukaryotes: **DNA polymerase β**

Extra: In prokaryotes, DNA polymerase I is involved in DNA repair and primer removal (due to its 5'→3' exonuclease activity). In eukaryotes, DNA polymerase β is the primary polymerase involved in DNA repair (specifically base excision repair).

Flashcard 4: What is the direction of DNA repair?_____

Answer: 5' to 3'

Flashcard 5: Which base excision repair enzymes are responsible for filling and sealing the gap from the excised bases? _____ (filling) and DNA ligase III (sealing)

Answer: DNA polymerase β

Flashcard 6: Xanthine is converted to _____ by xanthine oxidase

Answer: uric acid

Flashcard 7: Hypoxanthine is converted to _____ via xanthine oxidase

Answer: xanthine

Flashcard 8: Guanosine is converted to _____ via the enzyme purine nucleoside phosphorylase (purine salvage)

Answer: guanine

Flashcard 9: microRNA often leads to the _____ of target mRNA, thus causing decreased translation into protein

Answer: silencing/inactivation

Flashcard 10: One co-transcriptional modification is the addition of a _____ at the 5' end

Answer: 7-methylguanosine cap