Presentation on theme: "INTRODUCTION TO LINKED GENES AND SEX LINKAGE H. Biology/ Ms. Kim"— Presentation transcript:
1 INTRODUCTION TO LINKED GENES AND SEX LINKAGE H. Biology/ Ms. Kim
2 Locating Genes on Chromosomes Are located on chromosomesCode for protein that determines specific traits.Figure 15.1
3 Gene Linkage Linked genes Usually inherited together because located near each other on the SAME chromosomeGenes closer together on the same chromosome are more often inherited togetherEach chromosomeHas 100’s or 1000’s of genesSex-linked genes exhibit unique patterns of inheritance; genes linked on the X or Y chromosome
4 What is gene linkage?Thomas Hunt Morgan (1910) noticed that eye color in fruit flies and wing size always seemed to be inherited together in offspring.This seemed to go against Mendel’s Law of Independent AssortmentMorgan discovered chromosomes are a group of linked genesLaw of Independent Assortment was still true, but chromosomes assort independently, not genes.
5 Gene LinkageGenes located on the same chromosome will NOT sort independentlyThey will be inherited togetherGene Linkage:Tendency of 2 alleles (for different traits) to be inherited togetherThe closer the genes are, the more likely they are to be inherited togetherProbability that two genes will be inherited together is related to the distance between them
6 Mendel’s Principle of Independent Assortment? Remember: this refers to genes on separate chromosomesGene 1Gene 2
7 What would cause genes on the same chromosome to be inherited separately? Crossing over!
8 What is gene mapping?Location of Gene on a chromosome is it’s LOCUS