Section 11-3Exploring Mendelian Genetics

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????

Mendel Performed ATwo Factor Cross

He Crossed

Round/Yellow RRYYWith Wrinkled/Green rryy

This Provided The F1 Hybrids That He Needed.

To make a Punnet square of a cross with two traits first figure out the possible gametes.

RRYY All gametes would be RYrryy All gametes would be ry

All Hybrids would be RrYy

9 : 3 : 3 : 1

Expected ratio for independent assortment phenotypes

.

556556 Seeds ProducedSeeds Produced

315 Round/Yellow315 Round/Yellow FF11 Parental ParentalPhenotypesPhenotypes32 Wrinkled/Green32 Wrinkled/Green

PlusPlus

209 Unique Phenotypes209 Unique Phenotypes Can Only FormCan Only Form

ViaVia

9:3:3:19:3:3:1 IndependentIndependent

AssortmentAssortment

The Alleles For Seed Shape And Color Segregated

IndependentlyINDEPENDENT ASSORTMENT did occur.

Therefore These Alleles DO NOT

Influence Each Others Inheritance

The Principle Of Independent Assortment States That

Genes For Different TraitsCan Segregate

Independently During The Formation Of Gametes.

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.

2. Where Two or More Forms Of The Alleles Exist,

Some Forms Of The Allele Many Be

DominantAnd Others May Be

Recessive.

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.

5. Alleles Contained In Different Genes Usually Segregate Independently Of One Another

Key Concept:Some Alleles Are Neither Dominant Nor Recessive, And Many Traits Are Controlled By Multiple Alleles or Genes.

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)

Both Alleles Completely ExpressedRed Hair Cattle Crossed With White Haired Cattle Produce

Roan (Pink Brown) Cattle That Have Both Colored

Hairs.(Both Alleles Expressed Independently)

RED WHITE

ROAN

A Gene Is Controlled By >2 Alleles. Individuals Can Only Have 2 Alleles Populations Can Have More Than Two

Rabbit Fur Color Blood Types Eye Color

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