1. Mendelian Genetics

2. Gregor Mendel “The Father of Genetics” Austrian Monk and Mathematician
in the 1800’s
Even though he had no
understanding of DNA as genetic
material, he was able to correctly predict how traits were passed between generations.

3. Mendel’s Experiments Crossed pea plants
Cross - a mating of two organisms
*Each flower in the pic represents an entire pea plant

4. Experiment Explanation
P Generation
Purple flower plant x white flower plant
F1 Generation
All plants had purple flowers
The trait for white seemed to disappear
F1 Generation allowed to self fertilize
F2 Generation
Produced plants with purple flowers and plants with white flowers
Result – the trait for white had not disappeared…it had been hidden/masked

6. Understanding the Vocabulary

7. Allele
Alternative form that a single gene may have for a particular trait
Each parent gives 1 allele
Example: the gene for eye color has several alleles (or forms) like an allele for blue eyes, and allele for brown eyes, etc.

8. Genotype
The actual alleles you inherit from your parents (1 from mom and 1 from dad).
Usually expressed as letters.
Ex. XX or XY

9. Phenotype
The observable characteristic or outward expression of an allele pair
Physical appearance
Ex. XY is the Genotype; its phenotype is male.

10. Dominant Trait
The allele that is expressed (it has dominance over another)
Expressed as a capital letter
Ex. B=brown, b=blue. Bb genotype, its phenotype is brown.

11. Recessive Trait
An allele that is hidden or not expressed unless there are 2 recessive genes
Written as a lower case letter
Ex. bb=blue eyes

12. Homozygous 2 of the same alleles for a given trait (purebred)
Ex. BB (homozygous dominant) or
bb (homozygous recessive)

13. Heterozygous
2 different alleles for a given trait
Ex. Bb

14. How Mendel’s Pea Plants Helped us Understand Genetics
Ted-ed
How Mendel’s Pea Plants Helped us Understand Genetics

15. Vocab Review
A bug with the genotype L L is __________________ for leg genes Homozygous heterozygous
A bug with the genotype e e is __________________ for eye genes. Pure hybrid
A bug with the genotype A a is __________________ for antenna genes Pure hybrid

17. Monohybrid Cross
A cross that examines the inheritance of 1 specific trait.
Punnett Squares
A grid system for predicting the possible genotypes and phenotypes of offspring.

18. Examples!
Use a white board to conquer Punnett Squares!

19. FYI
Pea plants with purple flowers are dominant to pea plants with white flowers
Use “P” to represent the flowers in your Punnett Square

20. Homozygous x Homozygous
Cross a homozygous dominant purple flower plant with a homozygous recessive white flower plant

21. Heterozygous x Heterozygous
Cross a heterozygous purple flower plant with a heterozygous purple flower plant.

22. Heterozygous x Homozygous
Cross a homozygous recessive plant (white flowers) with a heterozygous plant (purple flowers).

24. Find a partner and 2 pennies!
Baby Lab
Find a partner and 2 pennies!

25. Vocab Review
What has to be true about the parents that show a DOMINANT allele for a trait, but have a baby that shows the RECESSIVE trait?
A. both parents are HOMOZYGOUS for the trait
B. both parents are HETEROZYGOUS for the trait
C. both parents are PURE for the trait
D. IMPOSSIBLE; Dominant looking parents can’t have a recessive looking offspring
B – Both parents are heterozygous!