G4 Flashcards
What is a prototroph
wildtype organism can grow on minimal medium
what is an auxotroph
biochemical mutant cant be grown on minimal medium
What is filtration enrichment
used on filamentous fungi etc
grow on minmal medium normal spores grow sending out mycelial networks so prototrophs are held b filter however autotrophs pass through and can be grown
what is pleitropic
when behaviours show multiple characteristics
what is killing enrichment
cells grown on lqd medium with antibiotic/antifungal which kills growing organism prototrophs grow faster than non growin auxotroph, dead organisms centrifuged to wash antibiotics then plated on solid medium
How do you obtain specific types of auxotrophs
minimal medium so all prototrophs grow quickly then filtered by killing enrichment, surviving organisms plated on minimal medium and argigine, so only remaining prototroph and arg- auxtrophs will grow, but no other auxotroph, isolate and test each individual growing colony on minimal medium and arginine
how can mutants be used to determine biochemical pathways
test each mutant for growth on a minimal medium plus each in turn of a range of possible precursors of e.g. tryptophan.
compound excreted bby each mutant is the one immediately before the block thus can be determined where a mutant is blocked from waht it secretes.
What is complementation?
when two strains of an organism with different homozygous recessive mutations that produce the same mutant phenotype produce offspring with the wild-type phenotype when mated or crossed.
Complementation occurs if mutations are in different genes.
each strain’s genome supplies the wild-type allele to “complement” the mutated allele of the other strain’s genome.
what is the cis/trans test for functional allelism?
most specific test for allelism - tests whether two recessive mutations are in the same genetic unit of function, the cistron. = complementation test
how is complementation carried out
by mating haploid a and alpha cells.
what phenotype do two non alelleic mutants give?
a wild type phenotype in trans because in both one has a wild type copy of each gene
what phenotype do two alllelic mutants give
mutant phenotype in trans because both copies of the gene are defective
Where can partial complementtion be seen
when dimeric or multimeric enxymes have 2 pps with deffects in different regions but can show partial through protein protein interaction.
what is tumour suppressor p53
guardian of genome
dna damaging agents activate and increase p53 levels, over expression of p53 induces arrest at g1 and g2/m and apoptosis - found on chromosome 17
how does p53 promote breast cancer suppression
repressed SHP-1 expression and induces trkA phosphorylation
