FOOTHILL HIGH SCHOOL SCIENCE DEPARTMENT Chapter 11 Introduction To Genetics Section 11-3 Exploring Mendelian Genetics

FOOTHILL HIGH SCHOOL SCIENCE DEPARTMENT Gregor Mendel Wanted To Know If: Segregation Was Truly Independent or Does The Segregation Of One Pair Of Alleles Affect The Segregation Of Another Pair Of Alleles????

FOOTHILL HIGH SCHOOL SCIENCE DEPARTMENT Independent Assortment Mendel Performed A Two Factor Cross –He Crossed Round/Yellow RRYY –With Wrinkled/Green rryy This Provided The F 1 Hybrids That He Needed.

FOOTHILL HIGH SCHOOL SCIENCE DEPARTMENT Independent Assortment F1 Hybrid RrYy

FOOTHILL HIGH SCHOOL SCIENCE DEPARTMENT

Independent Assortment 9 : 3 : 3 : 199 : 39 : 3 : 3

FOOTHILL HIGH SCHOOL SCIENCE DEPARTMENT Two Factor Cross F 2 All F 1 Plants Were Heterozygous or Hybrid In The F 2 Cross Would 1.The Dominant Alleles Stay Together 2.Or Would They Segregate Independently So Any Combination Of Alleles Would Be Possible??????

FOOTHILL HIGH SCHOOL SCIENCE DEPARTMENT Two Factor Cross F 2 Results 556 Seeds Produced 315 Round/Yellow F 1 Parental Phenotypes 32 Wrinkled/Green Plus 209 Unique Phenotypes Can Only Form Via 9:3:3:1Independent Assortment

FOOTHILL HIGH SCHOOL SCIENCE DEPARTMENT Two Factor Cross F 2 Results The Alleles For Seed Shape And Color Segregated Independently INDEPENDENT ASSORTMENT did occur. Therefore These Alleles DO NOT Influence Each Others Inheritance

FOOTHILL HIGH SCHOOL SCIENCE DEPARTMENT Key Concept The Principle Of Independent Assortment States That Genes For Different Traits Can Segregate Independently During The Formation Of Gametes.

FOOTHILL HIGH SCHOOL SCIENCE DEPARTMENT Summary of Mendel’s Principles 1.Inheritance of Biological Characteristics Is Determined By Individual Units Known As Genes. In Organisms That Reproduce Sexually, Genes Are Passed From Parents To Their Offspring.

FOOTHILL HIGH SCHOOL SCIENCE DEPARTMENT Summary of Mendel’s Principles 2.Where Two or More Forms Of The Alleles Exist, Some Forms Of The Allele Many Be Dominant And Others May Be Recessive.

FOOTHILL HIGH SCHOOL SCIENCE DEPARTMENT Summary of Mendel’s Principles 3.In Most Sexually Reproducing Organisms, Each Adult Has Two Alleles In Each Gene – One From Each Parent 4.These Alleles Are Segregated From Each Other When Gametes Are Formed.

FOOTHILL HIGH SCHOOL SCIENCE DEPARTMENT Summary of Mendel’s Principles 5.Alleles Contained In Different Genes Usually Segregate Independently Of One Another

FOOTHILL HIGH SCHOOL SCIENCE DEPARTMENT Beyond Dominant & Recessive Alleles Key Concept: Some Alleles Are Neither Dominant Nor Recessive, And Many Traits Are Controlled By Multiple Alleles or Genes.

FOOTHILL HIGH SCHOOL SCIENCE DEPARTMENT Incomplete Dominance Red Flower Crossed With White Flower Results In Pink Flower. In Incomplete Dominance The Heterozygous Phenotype Is Between The Homozygous Phenotypes. ( Both Alleles Expressed In One Cell)

FOOTHILL HIGH SCHOOL SCIENCE DEPARTMENT

Codominance Both Alleles Completely ExpressedBoth Alleles Completely Expressed Red Hair Cattle Crossed With White Haired Cattle Produce Roan (Pink Brown) Cattle That Have Both Colored Hairs. (Both Alleles Expressed Independently)

FOOTHILL HIGH SCHOOL SCIENCE DEPARTMENT Codominance REDWHITE ROAN

FOOTHILL HIGH SCHOOL SCIENCE DEPARTMENT Multiple Alleles A Gene Is Controlled By >2 Alleles.A Gene Is Controlled By >2 Alleles. –Individuals Can Only Have 2 Alleles –Populations Can Have More Than Two Rabbit Fur ColorRabbit Fur Color Blood TypesBlood Types Eye ColorEye Color

FOOTHILL HIGH SCHOOL SCIENCE DEPARTMENT Multiple Alleles

FOOTHILL HIGH SCHOOL SCIENCE DEPARTMENT Multiple Alleles

FOOTHILL HIGH SCHOOL SCIENCE DEPARTMENT Multiple Alleles

FOOTHILL HIGH SCHOOL SCIENCE DEPARTMENT Polygenic Traits Phenotypes Produced By The Interaction Of Several Genes.Phenotypes Produced By The Interaction Of Several Genes. –Human Skin Color Is Controlled By More Than 4 Different Genes. –Eye Color is Controlled By At Least 3 Genes

FOOTHILL HIGH SCHOOL SCIENCE DEPARTMENT Applying Mendel’s Principles Thomas Hunt Morgan – early 1900’s –Drosophila melanogaster Easy To RaiseEasy To Raise Produces Numerous Offspring Every 14 DaysProduces Numerous Offspring Every 14 Days Large ChromosomesLarge Chromosomes Susceptible To MutagensSusceptible To Mutagens