Molecular Genetics

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Heritable traits that can be assayed (markers) are of many different kinds:

• Visible (physical appearance): height, shape, color, growth rate, etc.
• Auxotrophic (growth requirements). For microorganisms such as baker's yeast, though some markers are visual markers affecting colony color or morphology, many are auxotrophic markers. Search here for terms such as 3-letter amino acid abbreviations for loci whose mutation causes a requirement for that amino acid for growth.
• Antibiotic sensitivities and resistances.
• Conditional: nutrition (auxotrophy); temperature ( ts mutants); light; developmental; etc.
• Molecular.

Characteristics of several biomolecules can serve as markers on the genetic chromosome.

• Antigenic
  • Blood group antigens are carbohydrates.
  • Histocompatibllity antigens are proteins. Discovered via tissue transplantation, MHC loci are polymorphic.
• Enzymatic
  • Isoenzymes are proteins.
• DNA-based
  • RFLP's (restriction fragment length polymorphisms)
  • RAPD's (random amplified polymorphic DNA)
  • AFLP's (amplified fragment length polymorphisms)
  • Microsatellite repeats--VNTR's
  • SSCP's (single strand conformation polymorphism)
  • SNP's (single nucleotide polymorphism)

• Uses
  • Genetic
  • Biomedical
  • Forensic