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INTRODUCTION TO LINKED GENES AND SEX LINKAGE H. Biology/ Ms. Kim.

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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 Genes – Are located on chromosomes – Code 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 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

4 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.

5 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

6 Mendel’s Principle of Independent Assortment? Remember: this refers to genes on separate chromosomes Gene 1 Gene 2

7 What would cause genes on the same chromosome to be inherited separately? – Crossing over!

8 Location of Gene on a chromosome is it’s LOCUS


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