Gene Linkage & Human Genetics PDF

“Happiness does not lie in happiness but in the achievement of it.” Fyodor Dostoevsky  Chapter 9 Section 9.17 & 9.19: Gene Linkages Learning Objectives ▪ Today you will learn to: ▪ Discuss how some traits can tend to be inherited together. ▪ Discover wha...

“Happiness does not lie in happiness but in the achievement of it.” Fyodor Dostoevsky  Chapter 9 Section 9.17 & 9.19: Gene Linkages Learning Objectives ▪ Today you will learn to: ▪ Discuss how some traits can tend to be inherited together. ▪ Discover what gene maps are and how they are produced. Unit Organizer Genetics is about The Inheritance including Unique of Traits according to to inheritance which can be Gregor predicted using determine patterns Mendel Probability Traits & Punnett Squares like in Phenotypes Genotypes Monohybrid crosses Dihybrid crosses Mendel ▪ It’s easy to see how genes on different chromosomes assort independently ▪ What about genes on the same chromosome? ▪ Would they inherit together? ▪ YES!  Applying Mendel’s Principles ▪ Thomas Hunt Morgan used Mendel’s work on fruit flies: ▪ Scientific name- Drosophila melanogaster ▪ Why? ▪ Small ▪ Easy to keep ▪ Able to produce large numbers in a short period of time ▪ Have few chromosomes Gene Linkage ▪ Thomas Hunt Morgan answered the question ▪ Working with fruit flies he found that genes on the same chromosome generally were inherited together ▪ But not always, because of crossing over! Gene Linkage Morgan discovered: ▪ Almost all of the traits Mendel studied happened to be on different chromosomes ▪ A chromosome is basically a group of linked genes ▪ The chromosomes assorted independently, not the individual genes ▪ Genes within a linkage groups inherited together.  Human Gene Linkage ▪ For example: ▪ Ear malformations in infants almost always coincide with kidney abnormalities. ▪ When chromosomal damage occurs it usually affects both ear and kidney formation. ▪ The genes are linked and tend to be inherited closely together and separate infrequently. Gene Maps ▪ Two genes on the same chromosome can be separated through crossing over, only if they are far enough apart ▪ The farther apart the genes are on the chromosome the more likely they will separate ▪ This is how genes were mapped for The Human Genome Project Section of chromosome carrying linked genes 17% 9% 9.5% Recombination frequencies Section Review 1. Discuss how some traits can tend to be inherited together. 2. What are gene maps, and how are they produced? How is crossing over involved?