1. Genetics

2. What do Bart, Lisa & Maggie all have in common?
Why?

3. Traits can be… DOMINANT recessive More likely to be seen
Dominant overpowers the recessive traits.
recessive
Less likely to be seen
Can sometimes be
“hidden” within your genes. or

4. Most of these characters are the same species.
But how are they different?

5. We inherit our traits from our parents
Alleles
every trait is decided by two alleles (one from Mom, and one from Dad)
They can be dominant or recessive
We get 23 chromosomes from Mom and 23 from Dad.
This equals 46 chromosomes.
Genes – the instructions for traits
We represent these alleles with letters.
Brown hair- dominant allele - B
Blond hair- recessive allele - b

6. Alleles Examples Curly hair – Dominant – C
Straight hair – recessive – c
Dimples – Dominant – D
No dimples – recessive – d

7. Phenotype The appearance of the organism. PHENO is like PHOTO
What you would be able to see in a photo?
spotted coat, short hair, long hair, floppy ears short ears
brown hair, curly hair, brown eyes, freckles, dimples, face shape

8. Genotype The genetic makeup of an organism.
This is not visible, but inside their genes (DNA).
Tongue rolling – dominant allele – T
Not able to roll tongue- recessive - t
Can roll tongue – TT, Tt
Cannot roll tongue - tt

9. PUNNETT SQUARES First, make a box with 4 squares inside it
Second, put both parents Alleles in the right spot.
Mom, Rr, can roll tongue
Dad, rr, can’t roll tongue
R r r

10. PUNNETT SQUARES Rr rr rr Rr Bring down each letter
Bring over each letter
This will make 4 possible combinations
R r r Rr rr rr Rr

11. PUNNETT SQUARES Rr rr rr Rr What are the possible Genotypes?
What are the possible phenotypes?
Give a ratio for each
R r r Rr rr rr Rr

12. Mutations