Transcript 11-5 Linkage & Gene Maps

Chapter 11
Introduction To Genetics
Section 11-5
Linkage & Gene Maps
FOOTHILL HIGH SCHOOL SCIENCE DEPARTMENT
Gene Linkage
Thomas Hunt Morgan
1910 Using Fruit Flies
– Discovered Linkage
• Some Genes Are Inherited
Together Counter To Mendel's
Principle Of Independent
Assortment
• Turns Out, It Is The
Chromosomes That Sort
Independently, Not Individual
Genes.
FOOTHILL HIGH SCHOOL SCIENCE DEPARTMENT
Gene Linkage
• Why Did Mendel Miss This?
– Six Of The Seven Genes He Studied Were
On Different Chromosomes.
– The Two That Were On The Same
Chromosome Were So Far Apart That They
Also Assorted Independently.
FOOTHILL HIGH SCHOOL SCIENCE DEPARTMENT
Gene Maps
Are Two Genes On The Same
Chromosome Linked Forever?
No!
They Can Separate If
Crossing Over Occurs In Meiosis
This Produces New Combinations Of
Alleles And Creates Genetic
Diversity
FOOTHILL HIGH SCHOOL SCIENCE DEPARTMENT
Gene Linkage
• Sturtevant, 1911
– Morgan’s Student
– Realized The Farther Away
Genes Were From Each
Other, The More Likely They
Would Be Separated If
Crossover Occurred
– This Allows Gene Mapping
FOOTHILL HIGH SCHOOL SCIENCE DEPARTMENT
Gene Map - Linkage
FOOTHILL HIGH SCHOOL SCIENCE DEPARTMENT