1. Bell Ringer: (5 min.)

2. Section 11-3: Exploring Mendelian Genetics

3. Independent Assortment
Mendel wanted to know:
Does the segregation of one pair of alleles affect that of another?
For example: Does the allele for seed color effect the shape of the seed?
1. To find this Mendel created a two factor cross and followed two different genes as they passed from one generation to the next.

4. The Two Factor Cross: F1
Crossed true breeding plants for round (RR) yellow (YY)peas
2. Genotype (RRYY)
With true breeding plants for wrinkled (rr) green (yy) peas
2. Genotype (rryy)
And proceeded to observe the offspring

5. The Two Factor Cross: F1 ry RY
RrYy

6. The F1 Results: 3. This shows that the dominant alleles are present:
Phenotype:
Heterozygous
Round Yellow Seeds
Genotype:
RrYy
4. Does this result show if genes segregate independently?
Nope

7. The Two Factor Cross: F2
5. Mendel took the F1 generation (heterozygous) and crossed them.
He wanted to see if the two traits would separate independently of one another or if dominant would stick with dominant and recessive stay with recessive.
Was very curious of the possible outcomes.

8. 10. The Two Factor Cross: F2 RY Ry rY ry

9. The F2 Results: 6. & 8. There was a total of 556 seeds produced:
Round Yellow: 315
Round Green: 105
Wrinkled Yellow: 104
Wrinkled Green: 32
7. There were seeds that displayed combinations not found in the parents (RRYY and rryy)
Did Independent assortment occur?
YES!

10. Let’s Look at the Numbers Again:
9. Count up the Phenotypes, what is the ratio?
9:3:3:1
Round Yellow: 9
RRYY, RrYy
Round Green: 3
RRyy, Rryy
Wrinkled Yellow: 3
rrYY, rrYy
Wrinkled Green: 1
rryy

11. 11. Independent Assortment
The alleles for a given trait segregate independently of one another and do not influence each other’s inheritance.

12. 12. A Summary of Mendel’s Principles
The inheritance of biological characteristics is determined by genes that are passed down from parents to their offspring
13. Two or more forms of a trait may exist (ex: Dominant and Recessive)
The copies of genes are segregated from each other when gametes are formed
The alleles for different genes usually segregate independently from one another

13. Beyond Dominant and Recessive
14. There are some alleles that are neither dominant or recessive, and many traits:
Genetics tends to be a bit more complicated than that:
The majority of genes have more than two alleles, and important traits are controlled by many different genes.

14. 15. Incomplete Dominance
Cases in which one allele is not dominant over the other
The heterozygous phenotype is somewhere between the two homozygous phenotypes
Ex:
Strawberry Blonde
4 ‘o Clock Plants

15. 15. Codominance Both alleles contribute to the phenotype Ex:
Both alleles will be shown in the offspring
Ex:
Erminette Animals
Black feathers is
codominant with white
Offspring show both colors
Humans
Proteins synthesis

16. 15. Multipe Alleles Genes that have more than two possible alleles
This does not mean that an individual can have more than two alleles for a gene
It means that there could be more than two possibilities in a population
Ex:
Rabbit fur color
Blood Types in humans

17. Multiple Alleles

18. 15. Polygenic Traits Traits that are controlled by two or more genes
Many traits are produced by the interaction of several genes
Ex:
Human Skin Color
4 genes control skin color
Human Eye Color

19. Applying Mendel’s Principles
Thomas Morgan- Geneticist that worked with Fruit Flies to test Mendel’s Principles of Segregation
16. Chose Fruit Flies because:
Small in size
Easy to take care of in a lab setting
Capable of producing large numbers of offspring very quickly
17. The conclusion:
Mendel’s Principles apply to not just pea plants, but other organisms as well

20. Genetics and the Environment
18. Genes are not the only factor for determining characteristics of an organism
The Environment plays a role as well
Ex: Sunflower Height is determined by the genes, but this will change depending on factors such as climate, water availability, and soil composition

21. X Exit Slip bbCc Bbcc Katy Perry Wolverine Hair Color: -B: Black
-b: Blue
Claws:
-C: No Claws
-c: Claws
bbCc
Bbcc

22. Solve the Cross:
Bbcc
bbCc