麻省理工大学：遗传学（Genetics）讲稿_lecture8

TETRAD ANALYSIS IN FUNGI Image removed to due to copyright considerations THE PRODUCTS OF A SINGLE MEIOSIS ARE PACKAGED IN A SAC(ASCUS)

TETRAD ANALYSIS IN FUNGI Image removed to due to copyright considerations. THE PRODUCTS OF A SINGLE MEIOSIS ARE PACKAGED IN A SAC (ASCUS)

THE PRODUCTS OF A SINGLE MEIOSIS Haploid Diploid A A IVision Meiosis Image removed to due to copyright considerations a

A A a a THE PRODUCTS OF A SINGLE MEIOSIS A a Haploid Diploid 1st division Meiosis X a A A a a A Image removed to due to copyright considerations. A a a A

Mendel 1. Segregation: Equal numbers of a and a .The phenotype resulting from a mutation in a single gene will segregate exactly 2A: 2a o Question in Tetradspeak Does the phenotype segregate2: 2? Yes. a and a are alleles of a single gene

Mendel 1. Segregation: Equal numbers of A and a •The phenotype resulting from a mutation in a single gene will segregate exactly 2A : 2a. •Question in Tetradspeak: Does the phenotype segregate2:2? Yes. A and a are alleles of a single gene

HOW DO WE KNOW WHETHER TWO GENES ARE LINKED? B b BB or a Non-Parental Dit ype PD a (a B

HOW DO WE KNOW WHETHER TWO GENES ARE LINKED ? X a b A B A A a a B B b b A B A B a b a b B B b A b A a a or A b A b a B a B Parental Ditype (PD) Non-Parental Ditype (NPD)

How do you determine linkage? You cross ab x ab and find in 100 tetrads 48 PD 52 NPD Are a and b linked

How do you determine linkage? You cross AB x ab and find in 100 tetrads: 48 PD 52 NPD Are A and B linked?

Mendel 1. Segregation equal numbers of a and a .The phenotype resulting from a mutation in a single gene will segregate exactly 2A: 2a Question in Tetradspeak Does the phenotype segregate 2: 2? Yes. a and a are alleles of a single gene 2. Independent Assortment (linkage): AB X ab .Tetradspeak: Are PD=NPD N Two genes are unlinked Two genes are linked

Mendel 1. Segregation: Equal numbers of A and a •The phenotype resulting from a mutation in a single gene will segregate exactly 2A : 2a. •Question in Tetradspeak: Does the phenotype segregate 2:2? Yes. A and a are alleles of a single gene. 2. Independent Assortment (linkage): AB x ab •Tetradspeak: Are PD = NPD Yes No Two genes are unlinked Two genes are linked

Independent assortment (linkage): AB X ab Tetradspeak: Are pd= npd Two genes are unlinked Two genes are linked

Independent Assortment (linkage): AB x ab •Tetradspeak: Are PD = NPD Two genes are unlinked Two genes are linked

Complete linkage of Two genes C AB AB AB Parental ditype AB AB AB AB

Complete Linkage of Two Genes AB X ab AB AB ab ab AB AB ab ab Parental ditype AB AB ab ab

The products of a Single Crossover A B Ⅹ A B AB Parental b Ab Recombinant ab recombinant Parental TETRATYPE

The Products of a Single Crossover A B a b X A B AB Parental A B Ab Recombinant a b aB Recombinant a b ab Parental X TETRATYPE

2. Independent assortment (linkage): AB X ab .Tetradspeak: Are PD= NPD Yes No Two genes are unlinked Two genes are linked TETRATYPE? NO 1% linked Map Distance =1/2TT centimorgans TOTAL

2. Independent Assortment (linkage): AB x ab •Tetradspeak: Are PD = NPD Yes No Two genes are unlinked Two genes are linked TETRATYPE? Yes NO 100% linked Map Distance = 1/2 TT centiMorgans TOTAL