Presentation on theme: "INTRODUCTION TO LINKED GENES AND SEX LINKAGE H. Biology/ Ms. Kim."— Presentation transcript:
INTRODUCTION TO LINKED GENES AND SEX LINKAGE H. Biology/ Ms. Kim
Locating Genes on Chromosomes Genes – Are located on chromosomes – Code for protein that determines specific traits. Figure 15.1
Gene Linkage Linked genes – Usually inherited together because located near each other on the SAME chromosome Genes closer together on the same chromosome are more often inherited together Each chromosome – Has 100’s or 1000’s of genes Sex-linked genes exhibit unique patterns of inheritance; genes linked on the X or Y chromosome
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 Assortment Morgan discovered chromosomes are a group of linked genes Law of Independent Assortment was still true, but chromosomes assort independently, not genes.
Gene Linkage Genes located on the same chromosome will NOT sort independently They will be inherited together – Gene Linkage: Tendency of 2 alleles (for different traits) to be inherited together The closer the genes are, the more likely they are to be inherited together
Mendel’s Principle of Independent Assortment? Remember: this refers to genes on separate chromosomes Gene 1 Gene 2
What would cause genes on the same chromosome to be inherited separately? – Crossing over!