Molicular Biology
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Molicular Biology

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Molicular Biology Molicular Biology Presentation Transcript

  • Types of Molecules
    • DNA: code for genetic information
    • RNA
      • mRNA intermediates in protein synthesis
      • rRNA carry out protein synthesis
      • tRNA translate info on mRNA into a.a.
    • Gene
    www.freelivedoctor.com
  • Nucleotide Components
    • Bases + sugar + phosphate
    • Bases
      • purine
        • adenine
        • guanine
      • pyrimidines
        • thymine
        • cytosine
        • uracil
    www.freelivedoctor.com
  • Bases www.freelivedoctor.com
  • Nucleotide Components
    • Sugars
      • ribose
      • Deoxyribose
      • Rings numbered using primes
        • C1 = 1’ etc
    • PO 4 3-
    www.freelivedoctor.com
  • Nucleotide Structure
    • Base-sugar-phosphate
    • Base attached to C1 of sugar
    • Phosphate attached to C5 of sugar
    • Usually nucleotides are triphosphates, but can be mono or di
    www.freelivedoctor.com
  • Nucleic Acid, a polymer of nucleotides www.freelivedoctor.com
  • Nucleic Acids
    • Polymer of nucleotides
    • Phosphodiester linkage
      • 3’ of one sugar to 5’ of other
      • vectorial
    • Sequence read 5’ -  3’
    • Previous slide is C-A-A
    • Next slide (a cartoon drawing) is A-T-G-C
    www.freelivedoctor.com
  • Phosphodiester Bond www.freelivedoctor.com
  • Chain elongation
    • 3’ hydroxyl on chain has unshared pair on oxygen
      • attacks phosphorus on first phosphate of new nucleotide
      • Nucleophilic attack
    • Driven by hydrolysis of PPi
    www.freelivedoctor.com
  • Chain elongation www.freelivedoctor.com
  • Base pairs
      • Bases are planar
        • sp 2 hybridization
        • Bases nonpolar
      • In Nucleic acids, there is base pairing
      • Complementarity
        • Purines always base-pair with pyrimidines
          • Cytosine hydrogen bonds with guanine
          • Thymine hydrogen bonds with adenine or uracil
        • Due to distancing and proximity of unshared pairs and hydrogens
    www.freelivedoctor.com
  • GC base pair www.freelivedoctor.com
  • AT base Pair www.freelivedoctor.com
  • A-U base Pair (RNA) www.freelivedoctor.com
  • Base Pairs (Cartoon drawing) www.freelivedoctor.com
  • DNA structure
    • Double helix
    www.freelivedoctor.com
  • DNA structure
    • B-DNA is most common
    • Antiparallel
    • bases inside
      • Hydrophobic
      • Perpendicular to helix
    • stands complementary
      • Very important for information transfer
      • Each strand a template for the other.
    • right handed
    • major and minor groove
    www.freelivedoctor.com
  • Other forms of DNA
    • Z - DNA left handed; structure not fully understood
    • A- DNA; tighter helix
    www.freelivedoctor.com
  • DNA Types B- DNA (most common) www.freelivedoctor.com
  • A-DNA (supercoiled) www.freelivedoctor.com
  • Z-DNA www.freelivedoctor.com
  • Look down Axis www.freelivedoctor.com
  • Sequence dependent structures
    • palindromes
    • hairpins
    • inverted repeats
    • mirror repeats
    www.freelivedoctor.com
  • RNA
    • codes for protein
    • no consistent secondary structure
    • single stranded
    • Ribose instead of deoxyribose
    • Thymine (T) replaced by Uracil
    www.freelivedoctor.com
  • RNA www.freelivedoctor.com
  • Transfer RNA www.freelivedoctor.com
  • Instability of RNA
    • RNA unstable due to reactivity of 2’ hydroxyl on ribose
    • Very labile
    • DNA extremely stable
    www.freelivedoctor.com
  • Nucleic Acid Chemistry
    • Denaturation
      • unzip by heating
      • reannealing
      • CoT curves: more GC=higher temp
    • Uses of DNA to find sequences
      • probes
      • forensic
    www.freelivedoctor.com
  • DNA probes
    • Take DNA from crime scene
    • DNA from suspect, random other person etc
    • See what matches
    www.freelivedoctor.com
  • Nucleic Acid Chemistry
    • Mutations
      • changes in sequence/structure
      • nonenzymatic changes
        • thymine dimers
        • deamination
        • oxidative damage
    www.freelivedoctor.com
  • Nucleic Acid Chemistry
    • Sequencing
    • PCR
    • Southern Blotting
    • Probes
    www.freelivedoctor.com
  • DNA sequencing, Sanger dideoxy method
    • 4 samples
    • Each gets template and nucleotides
      • One dideoxy nucleotide
      • Has no 3’ OH so chain can’t elongate
    • Sample 1
      • ddTTP…stops at T
    • Sample 2
      • ddATP…stops at A
    • Sample 3
      • ddCTP…stops at C
    • Sample 4
      • ddGTP…stops at G
    • Run on Gel
      • Read from bottom up
    www.freelivedoctor.com
  • Sample Sanger Gel www.freelivedoctor.com