1. Introduction to Genetics
Complete Dominance

2. Golden Doodle A Brief History
In the past, people did not understand how traits were inherited, but there were many guesses based on things that could be observed.
Golden Doodle

3. Who was Gregor Mendel?
He was known as the “FATHER OF GENETICS”
He discovered how traits were inherited
GENETICS – study of heredity (the passing of traits from parents to offspring)

4. Mendel’s Peas
Mendel did his study on pea plants which have many traits.

5. Some traits are dominant over others.
Dominant: an allele that is expressed whenever it is present.
It masks the effects of any other allele of that gene
represented with a capital letter (eg. T = tall allele in pea)
Alleles: the different forms of a gene
Tall x Short = all tall offspring (hybrids)
*Tall is the dominant trait

6. Some traits are recessive
Short is recessive in pea plants.
Recessive: an allele that is not expressed when a dominant allele for the gene is also present
represented with a lower-case letter
(eg. t – short allele in pea)
Individuals have two alleles -
Ex. TT or tt or Tt

7. Explaining the Cross
When a parent makes sperm or eggs, their genes separate        
The GAMETES (egg or sperm) contain either a T allele (tall) or a t allele (short)

8. GENOTYPE  -  the set of alleles for a trait
eg. TT, Tt, tt
 PHENOTYPE   - what it looks like, outward appearance
eg.tall, dimples, freckles

9. Homozygous: same alleles
Eg. TT or tt
Heterozygous: different alleles
Eg. Tt (capital always comes first)

10. Punnett Squares Punnett Squares:
Ex. A TT (tall) plant is crossed with a tt (short) plant. What are the genotypes and phenotypes possible?

11. Ex. A brown eyes heterozygous father is crossed with a blue eyes homozygous mother. Brown eyes are dominant to blue eyes.
Brown eyes = Bb
Blue eyes = bb
What is the percentage/probability of the offspring being blue eyed?
2 blue eyes offspring = 1 = 50 %
4 offspring total

12. What does this letter actually represent?
What is the diagram shown below called?
What does this letter actually represent?

13. Check for understanding
1.  A one-eyed purple people eater is crossed with a two eyed purple people eater.  All of their offspring have two eyes.   Which trait is dominant?

14. 2. If you use the letter E for this gene
2.  If you use the letter E for this gene.   What is the genotype of the offspring if the parents were EE x ee
    
3.  If you crossed the offspring with each other?  How many of the new offspring would you expect to have two eyes?
EE = two eyes
Ee = two eyes
ee = one eye