140-S08-Mar17

140-S08-Mar17 - Reading on inversions and their genetic...

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Unformatted text preview: Reading on inversions and their genetic consequences pp501-503 genetic mosaics: pp152-4 (Mitotic recombination…and cancer) I’ve asked to reserve a room from 7-9pm Wednesday, April 9, for a review session in connection with the midterm on Monday, April 14. I’ll announce where the session will be held as soon as I know myself. p518 (“Aneuploid Mosaics…”) pp731-2 (“What cells…”) I'll be holding office hours (once) during spring break and at a special time: Wed, March 26, 11a-12N Female +/+ Male mutagenize X +/+ + / + + / + a + / b + / F1 + / + + / + a + / + / + a + / F2 a / a +/+ X it would help if we could keep track of chromosomes and eliminate extraneous animals so that we don't have to rely on random inter se matings for the F2 cross: In connection with genetic screens & selections: Herman Muller gave fly workers Balancer chromosomes for this purpose (early ‘30s - '40s): (a) a chromosome you can distinguish from the others. dominant marker mutant alleles ( B ar, C url y , S tu b ble) (b) a chromosome that will not recombine with others crossover suppressors (multiple inversions) (c) a chromosome that cannot become homozygous recessive lethal or sterile alleles …not only to facilitate mutant screens (and selections) but also to faciliate the maintenance of the deleterious alleles recovered in such screens and selections. Three key features : p503: Fig. 14.17 (read about inversions and their genetic consequences on pp501-503) Balancer chromosomes: (2) use them to “ maintain ” deleterious recessive alleles of interest + / + let / + let / let & & let / + X let / + Problem without balancer: …hence parents must have carried let and some siblings do Must rely on matings with the let carriers to maintain the let allele. Balancer chromosomes: (2) use them to “ maintain ” deleterious recessive alleles of interest Problem without balancer: + / + let / + let / let & & + / + let / + & let / + X let / + + / + X let / + + / + + / + + / + X + / + let / + let / let & & let / + X let / + Three possible random sib matings: …but with a balancer chromosome: let / Bal-A- let -A + Dom let Inv-B- let-A- / Bal let-A- / Bal X let-A- / let-A- lethal let-A- / Bal O.K. Bal / Bal lethal Balanced lethal condition progeny just like parents by default let / Bal , = Balancer chromosomes: (2) used them to “ maintain ” deleterious recessive alleles of interest What about an X-linked recessive lethal? lethal let-A- / Bal O.K. female Bal / Bal sterile female Balanced condition lethal or sterile recessive female-specific sterile / Y let-A- / Y lethal male Bal / Y O.K. male let-A- / Bal let-A- / Y X or Bal / Y female male (1) use them to follow chromosomes in mutant screens...
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This note was uploaded on 08/01/2008 for the course MCB 140 taught by Professor Urnov during the Spring '08 term at Berkeley.

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140-S08-Mar17 - Reading on inversions and their genetic...

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