Linked Genes and Gene Mapping pick up packet

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Linked Genes and Gene Mapping **pick up packet off front table

Linked Genes and Gene Mapping **pick up packet off front table

Mendel • Law of independent assortment- during meiosis pairs line up on plate independent

Mendel • Law of independent assortment- during meiosis pairs line up on plate independent of pair above. – AND genes are on separate chromosomes What if they weren’t on diff Chromosomes? What would we See in the offspring?

Linked Genes • 2 or more genes found on same chromosome • Inherited together

Linked Genes • 2 or more genes found on same chromosome • Inherited together frequently Given 2 chromosome options… Which scenario would give you more Frequent linked inheritance? WHY?

WHY? • Genes close together often travel together • Less chance for “close genes”

WHY? • Genes close together often travel together • Less chance for “close genes” to be split during crossing over

How to determine if genes are really linked? • KEY: Look at recombinants in

How to determine if genes are really linked? • KEY: Look at recombinants in offspring of cross • EX: In fruit flies, tan body color is dominant to black and normal wing shape is dominant to vestigal wings. A hybrid male is crossed with a black vestigal winged female.

Calculate Recombination Frequency • Formula • < 50% = _________ • > 50% =

Calculate Recombination Frequency • Formula • < 50% = _________ • > 50% = _________ • 100% = _________

Gene Mapping • 1% recombo frequency = 1 MPU (c. M) • Example: –

Gene Mapping • 1% recombo frequency = 1 MPU (c. M) • Example: – Recombination frequency of genes A and C is 17% while the frequency of genes A and B is 7%. Map the chromosome AND identify how far apart genes B and C are located.

Linkage Practice

Linkage Practice

A Wild type fruit fly (heterozygous for gray body and normal wings) is mated

A Wild type fruit fly (heterozygous for gray body and normal wings) is mated with a black fly with vestigial wings. OFFSPRING: 778 - wild type 785 - black-vestigial 158 - black- normal wings 162 - gray body-vestigial wings What is the recombination frequency between these genes? Are they linked? Why/Why not?

A Wild type fruit fly (heterozygous for gray body and red eyes) is mated

A Wild type fruit fly (heterozygous for gray body and red eyes) is mated with a black fly with purple eyes. OFFSPRING: 721 - gray body/red eyes 751 - black body/purple eyes 49 - gray body/purple eyes 45 - black body/red-eyes What is the recombination frequency between these genes? Are they linked? Why/Why not?

Determine the sequence of genes along a chromosome based on the following recombination frequencies:

Determine the sequence of genes along a chromosome based on the following recombination frequencies: A-B = 8 map units A-C = 28 map units A-D = 25 map units B-C = 20 map units B-D = 33 map units

Determine the sequence of genes along a chromosome based on the following recombination frequencies:

Determine the sequence of genes along a chromosome based on the following recombination frequencies: A-C = 20 map units A-D = 10 map units B-C = 15 map units B-D = 5 map units