1. Bellwork: 4/2 Put your phone up  Week 4/1 - 4/5
Have you ever done Punnett squares before?
What is a gene? Allele?
Give an example of a gene & its possible alleles.

2. Today:
Bellwork
Part 2 Notes

3. Materials
Unit Book

4. This Week: Mon/Wed*: Meiosis Model & Video Tuesday: Part 2 Notes
Thurs/Fri*: Mendelian Traits Activity & Video

5. Next Week: Monday: PS Practice & Assign Project
Tues/Wed: Quiz, Sample Project, Pt. 3 Notes
Thursday: Dihybrid Practice & Pt. 4 Notes
Friday: Blood Type Practice & Pt. 5 Notes

6. Homework
Meiosis Poster due…
4th & 6th – Thursday
5th & 7th - Friday

7. Unit VI: Mendelian Genetics

8. Part II: Monohybrid Crosses

9. Objective ?s
What patterns of inheritance are observed across generations?
How do the combination of chromosomes received from each of our parents affect our body’s appearance and function?

10. Vocab Gene – a nucleotide sequence of DNA that encodes a protein
Example: Height
Allele – alternative forms of a gene (each individual has two alleles)
Example: Tall, short…

11. Vocab Dominant – overpowering trait Recessive – weaker trait
when dominant alleles are present, the organism will always exhibit that trait
Recessive – weaker trait
organisms will only exhibit recessive traits when the dominant allele is NOT present

12. Vocab
Dominant – CAPITAL LETTER
Recessive – lowercase letter

13. Vocab Homozygous – having identical alleles for the trait
Homozygous Dominant = TT
Homozygous Recessive = tt
Heterozygous – having two different alleles for the trait Tt

14. Vocab
Phenotype – an organism’s expressed physical traits – the one you observe
Example: tall
Genotype – an organisms genetic makeup; the combination of alleles in the homologous chromosomes
Example: height – TT, Tt, tt

15. Heredity Pre- Mendelian
Blending theory – heredity material from each parent blends in the offspring
Once blended, it is inseparable (cannot return to traits of parents
Example: red flowers crossed with white flowers create pink flowers

16. Gregor Mendel Austrian Monk
Studied science & mathematics at University of Vienna
While doing his genetic research he was a substitute natural science teacher at a local high school
Developed 2 laws of inheritance
Biological organism: garden peas

17. Think!
Why would Mendel choose to study peas?

18. Why Garden Peas? Detectable traits Easy to grow Short life cycle
Mendel chose seven features to examine
Easy to grow
Short life cycle

19. Why Garden Peas? Mating easy to control
Flowers contain both male & female reproductive organs
Allowed for both…
Self-fertilization – pollen fertilizes egg from same plant
Cross-pollination – pollen fertilizes egg from different plant

20. Think!
What would the difference between the self-fertilized offspring & the cross-pollinated offspring be?

21. Mendel’s Laws of Inheritance
Developed 2 laws of inheritance:
Law of Segregation
Followed single trait (monohybrid cross)
Law of Independent Assortment
Followed two traits (dihybrid cross)

22. Law of Segregation
Each individual has two alleles for each trait that separate during the formation of gametes
Alleles reside on homologous chromosomes
Gametes (haploid) contain only one allele
Fertilization brings two gametes together returning the 2 alleles to the offspring

23. Purpose of Punnett Square
Examines the probability of getting a particular phenotype based on combination of gametes
Each square in a monohybrid cross represents 25% chance or ¼ probability

24. Punnett Square Problem
Monohybrid Crosses – looking at a single trait
Identify genotype of parents
Determine possible gametes for each parent
Set up Punnett Square
Fill in square by combining allele from sperm and egg
Address question the problem asked
Cross two guinea pigs Ff x ff
F= short fur
f=long fur
Probability of long fur offspring?

25. Sample Problem
A plant that is homozygous recessive for shortness is crossed with a heterozygous tall plant. Using a monohybrid Punnett square, show what the offspring will look like.
List the phenotypes & their probabilities.
List the genotypes & their probabilities.

26. Sample Problem
Tim & Jan both have freckles, a dominant trait (F) but their son Michael does not. Use a punnett square to show how this is possible.
List the phenotypes & their probabilities
List the genotypes & their probabilities