DNA Polymorphism

Locus
1. anonymous locus
  1. DNA locus without any apparent function
    1. make up 98.5% of genome
      1. Most mutations occur here
2. designated location anywhere on a chromosome, single nucleotide or stretch of many nucleotides
3. Gene:
  1. coding locus: produce either a protein or functional RNA
4. change in DNA sequence can occur at any locus
  1. called: DNA Polymorphisms
    1. becomes a mutation when phenotype is affected
      1. 3 regions of genome that allow polymorphs to become mutations
        Regulatory sequences important for transcription
        Northern Blotting
        detect changes in RNA
        terminator
        Destroys termination site - longer product
        Promoter
        Prevent transcription machinary from binding
        Bind more strongly to promoter, enhance transcript rates
        PPEs and enhancers in Eukaryotes
        RNA Poly Bind more strongly or not at all
        Coding regions
        codon changes
        SNP
        silent or Synonymous mutaiton
        codon codes for same aa
        Missense (conservative)
        codon codes for chemically similar amino acid (transition)
        Missense (nonconservative)
        codon codes for chemically dissimilar aa (transmutation)
        Nonsense
        Premature stop codon
        SSLP
        Indel
        Framshift mutations
        insertion of nucleotide
        deletion of nucleotide
        Western Blotting
        detect changes in protein
        Intron Boundaries (eukaryotes only))
        All introns must be removed before translation
        Western Blotting
        protein
        Northern Blotting
        RNA
        GU-AG rule
        exon---AG /splice/ GU---intron--AG /splice/ GU---exon
        Mutations
        New Splice site formed (GC/A/G becomes GT)
        Splice site eliminated (GT becomes GC/A/G)
      2. Gene structure
        Prokaryotic gene
        Promoter
        -35: TTGACAT
        -10: TATAAT
        Attach sigma-70 and RNA polymerase enzyme that begins transctipion
        +1
        Transcription start site
        Shine-Dalgarno Sequence
        ribosome ids this site to find start codon for translation
        gene
        start codon
        start translation
        stop codon
        stop translation
        Transcription Terminator
        Rho-dependent
        intrinsic (hairpin)
        Eukaryotic gene
        Promoter
        -30 TATA box
        bound by RNA polymerase and GTFs
        PPEs
        upstream of promoter
        help make enhancesome for transcription
        +1
        Transcription start site
        gene
        start codon
        start translation
        stop codon
        stop translation
        Transcription Terminator
        Polyadenylation signal
5. Polymorphic
  1. 2 or more different DNA sequences at a DNA locus
3 types of DNA polymorphisms
1. Single Nucleotide Polymorphisms (SNPs)
  1. replacing 1 nucleotide with another
  2. 2 types of SNPs
    1. transitions
      1. diameter of double helix not changed
        repair mechs less likely triggered
      2. purine to purine: A->G or G->A
      3. pyrimidine to pyrimidine: C->T or T->C
    2. transversions
      1. changes diameter
        likely to trigger repair
      2. purine to pyrimidine (vice versa)
  3. 3 Causes of SNPs
    1. Replication error
      1. DNA pol adds incorrect base = mismatched base pair
      2. 1:10^10
    2. Tautomerization of base
      1. tautomeric forms of purines and pyrimidines allow them to base pair with wrong partner
        Cause SNP in one daughter strand after DNA replication
    3. Spontaneous/Induced Lexions
      1. Mutagen
      2. replacing a base in DNA
      3. altering base so it mispairs
      4. damage base so no pairing
2. Simple Sequence Length Polymorphisms (SSLPs)
  1. repetitive sequence of nucleotides
  2. # of repeats can vary from person to person
    1. which allele at the loci = DNA fingerprint
      1. Each person is unique
        Basis of CODIS system
  3. 3 types of SSLPs
    1. microsatellites
      1. repeated sequence of 2-3 nts
    2. short tandem repeats (STRs)
      1. repeating sequence of 4-6 nts
    3. variable number tandem repeats (VNTR)
      1. dozens of nts repeated
  4. Cuases of SSLPs
    1. Slippage
      1. Insertion
        Daughter strand slips during replication
      2. Delection
        Template strand slips during replication
      3. Observed in second round of replication
3. Large-scale chromosomal changes
  1. Copy Number Variants (CNV)
    1. whole chrom or gene
  2. Relocation of genetic material
    1. Translocation
      1. segment from another chromosome
    2. Inversion
  3. Gain of Genetic material
    1. extra chromosomes
    2. Duplication
    3. Increase copy number
  4. Loss of genetic material
    1. Deletion
    2. Missing Chromosome
    3. decrease copy number

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DNA Polymorphism

Beschreibung

Zusammenfassung der Ressource

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