1. Mendel’s Laws Apply to Genes on Separate Chromosomes
Mendel’s Genetics
Mendel’s Laws Apply to Genes on Separate Chromosomes

2. Where are our genes?
Chromosomes are made of DNA and contain genes that have different versions or alleles. Combinations of genes make up our traits or characteristics.

3. 3 Laws Mendel Studied about our Genes
Law of Segregation
Law of Dominance
Law of Independent Assortment

4. Law of Segregation Gametes get one copy of each homologous chromosome
What would happen if you got less or more than one?

5. Segregation of Sex Chromosomes
Males are XY and Females are XX
All eggs contain an X
Sperm either contain an X or Y
SRY gene on Y
Chromosome makes you
Form testes and appear
male

6. Probability can be shown with a Punnett Square
Probability is a prediction based on what is known.
Actual results can deviate from what is expected.
Probability resets each time.
A couple has 5 girls and are pregnant again. What is the probability that their 6th kid is a boy?

7. Karyotype Chart organizing chromosomes in developing embryo.
Cells taken from placenta in process called amniocentesis
See if you can determine:
Sex
Health

8. Normal Female
Normal Male
Trisomy 21 (Down’s Syndrome)
Turner’s Syndrome

9. More Necessary Vocabulary
Genotype: Combination of alleles (Letters)
Homozygous: Both letters represent same allele (aa, AA)
Phenotype:
How and organism looks.
Heterozygous: Hybrid, or both alleles (Aa)

10. Law of Dominance
Dominant (capital letters) traits overpower recessive traits (lowercase letters).
Dominant traits are NOT more common! Example: Polydactly

11. Punnett Square: Shows outcome of mating between to individuals
Let’s use Mendel’s Peas to Practice! Dominant Traits are shown first

12. Easy
A smooth pea whose genotype for seed shape WW is crossed with a seed that is wrinkled ww.
Will their offspring be wrinkled or smooth?
What will be the % of the genotypes of their offspring?

13. Two tall pea plants were crossed and they ended up with the following results:
75% tall offspring; 25% short offspring.
What are the genotypes of the parents?
Medium

14. Hard
Two pea plants are crossed and 80 seeds are produced. Of those 80 seeds, 46 produce purple flowers and 34 produce white flowers.
Use a Punnett Square to show if this is possible.
What are the genotypes and phenotypes of the parents?

15. Mendel’s Law of Independent Assortment
Homologous chromosomes line up randomly during meiosis and therefore many different gene combinations can be produced.

16. Back to Mendel’s Peas
A pea homozygous recessive (wrinkly green) for the traits shape and color is crossed with a homozygous dominant (smooth yellow) plant
What will the F1 (first generation) look like?
What will the second generation look like?

17. First..Find the parental genotypes
First Generation
Homozygous Dominant
Homozygous Recessive

18. Second FOIL for gametes
First Generation
Parent 1: SSYY
Parent 2: ssyy

19. Make a 16 box Punnett Square, one parent on each side, two letters on top of each box, 4 letters inside each box!

20. Analyze Data
What are the expected portions of each phenotype?

21. Generation 2
Parent 1:
Parent 2:

22. Foil for Gametes
Parent 1: F O I L
Parent 2:

23. Punnett Square…2 letters above each box, 4 letters in each box

24. Analyze for independent assortment of phenotypes

25. Corn Activity
You will determine if your baby corn, belongs to the parent corn!
The Punnett Square is hypothesis showing probability, you must determine if the actual results match the expected results!