Biosynthetic pathways - Experiment 1 Flashcards
What is the one gene - one enzyme hypothesis?
A single gene encodes the information for a single enzyme
Why doesn’t the pathway work very well if the reactants are simply mixed into a cell?
Enzymes are needed to catalyze the reactions so they occur fast enough
What is a gene?
A sequence of DNA that encodes a protein
What are alleles?
Different forms of the same gene caused by variations in the DNA
What are prototrophs?
A strain with no mutations in any of the genes encoding the enzymes, so the entire pathway is functional. All alleles are wild-type
What are auxotrophs?
A strain with a mutation in one or more enzymes, so the pathway is non-functional
How can a mutant allele possibly affect the protein produced?
Can either stop it from being produced or can produce an abnormal protein that isn’t functional
How can we determine if a strain is prototrophic or auxotrophic?
Plate it on minimal media. If it grows, it is a prototroph, if it doesn’t it is an auxotroph
What is present in minimal media?
The minimum amount of nutrients so that functional biochemical pathways are required for growth. Contains only the precursors for the pathways
What is present in complete media?
The end products of biochemical pathways as well as being enriched with lots of vitamins and minerals that help with growth
How can we determine if a strain is auxotrophic or if it isn’t viable?
Plate it on complete media. If it grows, it is an auxotroph, if it doesn’t it isn’t viable
How can an auxotrophic strain be rescued?
By supplementing the minimal media with the end product or with an intermediate product downstream of the blocked step
Why can’t the enzymes in the pathway be used as supplements?
They would denature in the process of making the plate
Why might a strain grow on complete media but not the plate supplemented with the end product of a particular pathway?
The strain has a mutation in a different pathway
