1. Inheritance
Mendel – Found that alleles show up in
predictable patterns and that some alleles
show up more often than others
• Homozygous (Pure-Breeds) - both alleles
are the same (PP or pp)
• Heterozygous (Hybrids) - both alleles are
different (Pp)
• Carriers – heterozygotes for a recessive
trait

2. Homozygous
Pure-Breed Crosses result in:
100% chance dominant phenotype

3. Heterozygous
Hybrid Crosses result in:
75% chance dominant phenotype
25% chance recessive phenotype

4. Compare
What makes the difference between a 100%
chance of the dominant phenotype and only
17% chance of the dominant phenotype ?
Pure-Breed Crosses result in: Hybrid Crosses result in:
100% chance dominant phenotype 75% chance dominant phenotype
25% chance recessive phenotype

5. Generations
Parents: P1 generation
First Generation: First Filial (F1)
Second Generation: Second Filial (F2)
Third Generation: Third Filial (F3)

6. Chance of Inheritance
100% chance 75% chance 75% chance 0% chance

7. Alleles can be tracked through multiple
generations and probabilities determined
Parents: P1 generation
First Generation: First Filial (F1)
100% chance dominant phenotype
Second Generation: Second Filial (F2)
75% chance dominant phenotype
Third Generation: Third Filial (F3)
63% chance dominant phenotype

8. Inheritance
Alleles can be tracked through multiple
generations and probabilities determined
Parents: P1 generation
First Generation: First Filial (F1)
100% chance dominant phenotype
Second Generation: Second Filial
(F2)
75% chance dominant phenotype
Third Generation: Third Filial (F3)
63% chance dominant phenotype
100% chance 75% chance 75% chance 0% chance

9. Practice
• Video on making punnett squares
• In your notebook complete the Probability
(Long vs Short Big Toe) Lab.

10. Summary of Mendel’s Principles
Gregor Mendel’s work forms the basis of modern genetics:
• Genes are passed from parent to offspring
• Some forms of genes (alleles) are dominant while others are recessive
• Genes randomly segregate (independent assortment) when gametes are formed
• The alleles for different genes usually segregate independently of one another
Linked genes (genes that occur very close
to one another on a chromosome) are the
exception
Write these 4 ideas
from Mendel in your
notebook

12. DNA  Chromosomes
• From Chromosome to DNA
• How DNA is packaged animation
• Meiosis is how DNA is copied and
sepereted to make gametes (sperm and egg)
• Complete cornell notes for the Meiosis
video and glue onto page ___ of your
notebook
– What is the purpose of Meiosis and Mitosis?

13. • Complete the lab “Why don’t we look like
our siblings” and glue in your notebook

14. Solving Punnett Squares
If a round pea plant (AA) is crossed
with a wrinkled pea plant (aa), what
percent of the offspring will be:
• Round? Solve these
• Wrinkled?
If two heterozygous round pea
in your
plants are crossed, what percent of
the offspring will be: notebook.
• Round?
• Wrinkled?
If a heterozygous round pea plant is crossed
with a homozygous wrinkled pea plant, what
percent of the offspring will be:
• Round?
• Wrinkled?