Genes and Proteins Flashcards
Minimal Media (MM)
Carbon source
Energy source
Salts
Complete Media (CM)
Amino acids
Sugars
Lipids
Nucleotides
Strains
Cells/organisms within a species that has a unique genotype and phenotype
Phototroph
Wild type
Genes all +
Grows on CM and MM
Auxotroph
Mutant type
One gene is -
Grows on CM
What did Srb and Horowitz Discover?
Biochemical pathway analysis
What is the one-gene-one-enzyme hypothesis?
One gene encodes only for one enzyme
Steps of the Srb and Horowitz Experiment
- Exposed WT cells to UV radiation (1 mutation per cell)
- Collected cells with random DNA damage (mutant strains)
- Collected mutant strains unable to make the amino acid arginine
- Grew the arg- strains on ornithine, citrulline, and arginine
Conclusions from the Srb and Horowitz Experiment
WT cells can make arginine with this pathway
ornithine -> citrulline -> arginine
Mutant cells can’t make arginine because one of the steps are blocked
Each enzyme is made by one gene
The Purpose of Biochemical Pathway Analysis
To determine how a cell/organism synthesizes an organic molecule
Each mutant strain has a single mutation
Results of a WT Appearance
The nutrient applied has rescued the mutant so the nutrient is after the blocked step
Results of a Mutant Appearance
The nutrient applied has not rescued the mutant so the nutrient is before the blocked step
Positive Controls
If the experiment worked these will be positive
Negative Controls
If the experiment worked these will be negative
Experimental Results
We have to do the experiment to find out what these are
