Transcript 11-3 Exploring Mendelian Genetics

Section 11-3
Exploring 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 A
Two Factor Cross

He Crossed
Round/Yellow

With
Wrinkled/Green
RRYY
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 RY
rryy All gametes would be ry
All Hybrids would
be RrYy
9:3:3:1
Expected
ratio for
independent
assortment
phenotypes
.
556 Seeds Produced
315 Round/Yellow
F1 Parental
Phenotypes
32 Wrinkled/Green
Plus
209 Unique Phenotypes Can Only Form
Via
Independent
9:3:3:1
Assortment
The Alleles For Seed Shape And
Color Segregated Independently
INDEPENDENT ASSORTMENT did occur.
Therefore These Alleles
DO NOT
Influence Each Others
Inheritance
The Principle Of Independent
Assortment States That
Genes For Different Traits
Can 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
Dominant
And 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 Expressed
Red 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
