Notes taken during lecture

33 views3 pages
28 Jan 2011
School
Department
Course
LECTURE โ€“ January 27th
Extensions to Mendelian genetics
๎€Law of segregation still held โ€“ but geno-pheno relationship modified
๎€Pleitropy, epistasis, etc. โ€“ effects at one gene or MULTIPLE genes?
๎€Independent assortment come into play with dihybrid crosses
๎€Monohybrid crossing โ€“ equal segregation
Always recessive โ€“ always masked
Bateson did crossesโ€ฆ
๎€F1 โ€“ new phenotype โ€“ walnut
oWeird
oIncomplete dominance perhaps????
๎€Cannot self animals โ€“ but cross F1 male with F1 female
oExpect in F2 1:2:1 ratio of walnut, rose, and pea
๎€Single phenotype showed up โ€“ a fourth!!
oCannot be accounted for because Mendel has 3 phenotypes
oCannot break down into one to two to one ratio
๎€Saw numbers as nine to three to three to one ratio
oInstead of two genes influencing two different traits
oActually two genes influencing ONE phenotype
๎€Cf. pleiotropy โ€“ one gene with multiple phenotypes
oActually recover expected ratios โ€“ good
oWalnut โ€“ double heterozygote โ€“ since parents were inbred lines
oTwo genes contributing to one phenotype โ€“ but everything else fits with
Mendel
Crucial cross to understanding
๎€White crossed โ€“ blue offspring
๎€Crossed F1 โ€“ white and blue result
๎€To get blue, must have dominant phenotype at two genes
oAt least one big a and at least one big b
๎€Otherwise, end up being white
๎€These are mutants for the same phenotype โ€“ but mutants from different genes
oSame gene โ€“ cross white, get white
oDifferent gene โ€“ combining them in f1, get blue phenotype
๎€Think of it in genetic pathway
oKnock out function
oA gone โ€“ no colour โ€“ white phenotype
oB gone โ€“ no colour โ€“ white phenotype
oBoth knocked out โ€“ white phenotype
๎€Complementation โ€“ cross two mutants and recover the wild type in f1
oTo get blue โ€“ both genes must be functional
oRight hand โ€“ mutation in gene 2
oCrossing mutants
www.notesolution.com
Unlock document

This preview shows page 1 of the document.
Unlock all 3 pages and 3 million more documents.

Already have an account? Log in

Document Summary

Law of segregation still held but geno-pheno relationship modified. Independent assortment come into play with dihybrid crosses. cannot self animals but cross f1 male with f1 female: expect in f2 1:2:1 ratio of walnut, rose, and pea. single phenotype showed up a fourth: cannot be accounted for because mendel has 3 phenotypes, cannot break down into one to two to one ratio. saw numbers as nine to three to three to one ratio: instead of two genes influencing two different traits, actually two genes influencing one phenotype. cf. pleiotropy one gene with multiple phenotypes: actually recover expected ratios good, walnut double heterozygote since parents were inbred lines, two genes contributing to one phenotype but everything else fits with. crossed f1 white and blue result. To get blue, must have dominant phenotype at two genes: at least one big a and at least one big b.

Get access

Grade+20% OFF
$8 USD/m$10 USD/m
Billed $96 USD annually
Grade+
Homework Help
Study Guides
Textbook Solutions
Class Notes
Textbook Notes
Booster Class
40 Verified Answers
Class+
$8 USD/m
Billed $96 USD annually
Class+
Homework Help
Study Guides
Textbook Solutions
Class Notes
Textbook Notes
Booster Class
30 Verified Answers