BIOL1003 Lecture Notes - Lecture 12: Melanocortin 1 Receptor, Hbb, Tyrosinase
Genotype to phenotype
Genotype
Phenotype
Many biological macromolecules are polymers
Polymers are chains made up of repeats of a monomer unit bonded together
covalently (covalent bonds are strong bonds which arise from the sharing of
electrons between two atoms)
Polymer Monomer Bond connecting monomers
DNA Deoxyribonucleotide Phosphodiester bond
RNA Ribonucleotide Phosphodiester bond
Protein Amino acid Peptide bond
Information is digital- order of bases or amino acids
Genotype determines phenotype
Genotype: the genetic make-up of an organism
Phenotype: the set of detectable properties, or traits, of an organism
Beadle and Tatum’s experiment
1940s
Worked with the fungus, Neurospora, which is a prototroph, meaning that it can
synthesise all organic molecules required for growth from sugars and inorganic ions
Beadle and Tatum selected mutants that were auxotrophs, meaning they required
particular organic molecules to grow
Each auxotrophic mutant was tested to find out which organic molecules had to be
supplied to allow growth
Three arginine auxotrophs were found, and were crossed with each other to find out
if they all had the same mutation
Mutations in three different genes resulted in the same phenotype: a requirement
for the amino acid, arginine
Three genes, one phenotype?
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Document Summary
Polymers are chains made up of repeats of a monomer unit bonded together covalently (covalent bonds are strong bonds which arise from the sharing of electrons between two atoms) Information is digital- order of bases or amino acids. Genotype: the genetic make-up of an organism. Phenotype: the set of detectable properties, or traits, of an organism. Worked with the fungus, neurospora, which is a prototroph, meaning that it can synthesise all organic molecules required for growth from sugars and inorganic ions. Beadle and tatum selected mutants that were auxotrophs, meaning they required particular organic molecules to grow. Each auxotrophic mutant was tested to find out which organic molecules had to be supplied to allow growth. Three arginine auxotrophs were found, and were crossed with each other to find out if they all had the same mutation. Mutations in three different genes resulted in the same phenotype: a requirement for the amino acid, arginine.
