BIOL 3333 1st Edition Lecture13Outline of Last Lecture T.H MorganGene OrderRecombinationAssortmentRFAscomycetesCurrent LectureIn an AB x ab cross, parental ditype:AB AB or ab ab - for PD the same combination is found in spores as it is in parentsIn an AB x ab cross, non parental ditype:- Ab Ab or aB aB - alleles have nonparental combinations in sporesIn an AB ab cross, tetra type or TT: AB, Ab, aB, ab - all possible combinations - both parental and nonparental are present in sporesIn an AB x ab cross, how do we know if the A and B loci are linked?- if they’re linked the parental ditypes should be MUCH greater than the nonparental ditypes?PD>>NPD How do we produce a NPD if genes are linked?- a double strand crossover is the only way for this to happen- this is a rare eventIn an AB x ab cross, how do we know if the genes are NOT linked?- the parental ditypes should be appoximately equal to the non parental ditypesPD = NPD How do we determine the distance between the gene and the centromere?- its the percentage of total ASCI showing second division segregation pattern divided by 2 To determine the distance between A and B:Mitotic Crossing-Over:- crossing over can also be detected during mitosis- its frequency is often 10,000 fold less than observed during meiosisThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.Curt Stern:- A demonstation of somatic cell grossing over during development- He studdied the X linked genes yellow and singed- Stern found that y+ sn/y+ sn x y sn+/Y males yields singed females and yellow males What causes a mosaic pattern?- chromosomal nondisjunction or chromosomal loss during mitosisWhat kind of frequency does Mitotic Recombination occur?- at a low frequency Why is it difficult to establish linkage relationships by traditional approaches in human pedigrees?- low number of progeny- it is difficult to set up a “testcross” situationWhat can be used to establish linkage from recombination data?- population studies and probability based on the likelihood of linkageWhat can complementation analysis and somatic cell hybridization used to do?- find linkage to human chromosomes Lod Score:- a statistical analysis for determining the probability of obtaining a particular pedigree at some specific recombination frequency relative to obtaining the same pedigree and assuming independent