Gene Interruption Flashcards
Describe a metabolic pathway
Multistep process that either synthesizes (ex. amino acids, sugars) or degrades a complex molecule (ex. cellular respiration breaks down sugars)
What is an anabolic pathway?
A metabolic pathway that synthesizes complex molecules with the sequential action of genes and enzyme catalysts
What is a catabolic pathway?
A metabolic pathway that breaks down complex molecules through the sequential action of genes and enzymes as catalysts
Describe how metabolic pathways work
Genes work together in sequential order to produce a final product
if all the genes in a pathway are functional, they will produce enzymes to convert a compound to another compound in a step process
ex. Met 2 codes for enzyme homoserine transacetylase to convert homoserine to cysteine
then Met B codes for cystothionine gamma synthetase to convert cysteine to cystathionine… etc.
What happens if a gene in the pathway is not functional?
the gene will not be able to code for the enzyme that will convert the current compound to the next compound
What is Neurospora?
A haploid fungus
Model organism
Why is Neurospora a model organism?
It is a simple organism that is easy to study
mates quickly
mycelium is multinucleate (haploid)
if two different fungi have different mating types and come into contact, they can fuse to create a diploid cell that will undergo meiosis to recombine and produce new haploid offspring
they synthesize everything they need to grow
Describe prototroph
An organism that has the wild type phenotype and no mutations and can grow on minimal plating (has everything it needs)
Describe auxotroph
An organism that has a mutation in a gene required to synthesize an essential molecule
cannot grow on minimal medium
What does minimal medium usually contain?
minerals, water, a carbon source (glucose usually)
How are the genes involved in the synthesis of a particular amino acid studied?
Geneticists screen for mutants by looking for auxotrophs
What kind of medium will an auxotroph be able to grow on?
Minimal medium + the essential molecule they cannot produce
How do geneticists screen for mutants?
take prototrophic neurospora and radiate with mutagens (ex. X ray) to create mutations
plate these on complete medium to allow both prototrophs and auxotrophs to grow
transfer to minimal medium to determine which are auxotrophs (will not grow)
auxotrophs transferred to minimal media + different amino acids to identify the pathway
mutant strains that required methionine to grow are methionine auxotrophs
Describe a complementation test
a test to cross mutants to determine the number of genes involved in the mutation
What happens if you give a mutant a compound that is made in the metabolic pathway after the step where the pathway is blocked?
the mutant can make the end product
What happens if you give a mutant a compound that is made in the metabolic pathway before the step where the pathway is blocked?
The mutant will not be able to make the product
What are the steps of identifying genes involved in determining petal colours in peas (for example)?
expose plants to mutagens to create mutations
look at offspring to identify and isolate mutants in gene for petal colour = peas with non-wild type phenotype
T or F: many phenotypes are controlled by more than one gene
true
How do you identify if the mutation occurs in the same gene or in different genes?
- complementation test
2. analyze double mutants
how do you get the double mutants?
by crossing mutants from the complementation test