Section 4 Flashcards
Transitions vs Transversions
-Point mutations
Purines= A,G (single ring) Pyramidines= C,T,U (double ring)
-Transitions= Py–>Py or Pr–>Pr
-Transversions= Py–>Pr or vice versa
-Transitions= more frequent even though transversions= more probable
Missense Mutation
- Nonsynonymous mutation
- Diff AA
- Neutral, detrimental, or beneficial
Nonsense Mutation
- Stop codon
- Detrimental
Silent Mutation
- Synonymous Mutations= same AA
- No effect usually
Spontaneous mutations
-Abnormalities by biological process
Strand Slippage
-Spontaneous Mutation
-DNA pol temporarily dissociates during replication and stem loop forms
Ex: ALS GGGGCC
Germline Mutation
- Occurs in egg or sperm
- Passes to offspring
Somatic Mutation
- Occurs in somatic cell
- Passed w/in organism (mosaicism), but not from parent to offspring
Mismatch Repair
- Corrects misincorperation of bases after replication
- Detects bulge in helix and fixes based on parent strand’s methylation
Base Excision Repair
- Corrects single damages nucleotides
- Ex: AP sites
Nucleotide Excision Repair
- Corrects thymine-thymine dimers
- Repair of UV damage
Repair in CRISPR
- Homologous Recombination
- –Exonuclease trims back DSB
- –Sister chromatid atcs as template to repair damaged strand
- Non-homologous endjoining
- –Exonuclease trims back DSB
- –Ligase seals back together (deletion results)
Depurination
- Removal of purine base from deoxyribose
- -Creates apurinic site
- DNA pol places adenine opposite if not repaired b4 next replication
Deamination
- Loss of NH2 GROUP
- Affects mthylated CpG islands
- Changes C-G to A-T
Restriction Enzymes
-Nucleases that cut put DNA at specific recognition sequences