Plan for the Day

1. Plan for the Day • Seating Chart & Group Cards • Notes: Introduction Genetics • Activity: Class Trait Variation • Exit Ticket: In class assessment • Homework = Bring Your Text book.

2. Chapter 11 How does an organism pass its characteristics on to its offspring?

3. Learning Targets • I can describe where an organism gets its unique characteristics. • I can describe how the different forms of a gene are distributed to offspring.

4. Genetics • The scientific study of heredity

5. Section 11- 1 How it all began Gregor Mendel (1822-1884) • Known as the father of genetics • Worked with pea plants

6. Mendel’s Pea Plants He observed 2 traits for each part of the plant.

7. Mendel’s Pea Plants He came up with the concept of alleles. He noticed that alleles are hereditary, and that you can predict the probability of the offspring having certain alleles.

8. Mendel’s Pea Plants He observed that some traits dominated over others For instance, if you “crossed” a round seed-pod plant with a wrinkled seed-pod plant you generally get a round seed-pod plant. Mendel Video

9. Mendel’s Pea Plants

10. Mendel’s Pea Plants What does “crossing” the pea plants mean? It means to mate a plant with another plant by pollination. • Garden peas are both self-fertilizing and cross-fertilizing. • self-fertilizing – a plant’s pollen grains fertilize its own egg cells in the ovary. • cross-fertilizing – a plant’s pollen grains fertilize another plant’s egg cells in the ovary.

12. Genes and Dominance • The offspring of crosses between parents with different traits are called Hybrids • When Mendel crossed plants with different traits he expected them to blend, but that’s not what happened at all. • All of the offspring had the character of only one of the parents

13. Mendel drew two conclusions 1. Inheritance is determined by factors that are passed from generation to generation – today we call these factors genes

14. Alleles (uh LEELZ) • Different forms of a gene • Plant Height • One form produced tall plants • Another form produced short plants.

15. Mendel’s 2nd conclusion 2. The Principal of Dominance • Some alleles are dominant and some are recessive

16. dominant • Covers up the recessive form Ex.) T = tall

17. recessive • Gets covered up in the presence of a dominant allele Ex.) t = short

18. Quick Lab Period 6 Copy the data table into your notebook. Write a prediction. We will collect our data together starting with Trait A. Those with free ear lobes move to the left side and those with attached to the right. Count the number in each group and record. Repeat for B to E.

19. Quick LabPeriod 4 Copy the data table into your notebook. Write a prediction. We will collect our data together starting with Trait A. Those with free ear lobes move to the left side and those with attached to the right. Count the number in each group and record. Repeat for B to E.

20. Segregation • Mendel wanted to answer another question Q: Had the recessive alleles disappeared? Or where they still present in the F1 plants? • To answer this he allowed the F1 plants to produce an F2 generation by self pollination

21. P1 Parental F1 F2 Tall Short All Tall 3 tall : 1 short 75% tall 25% short

22. The F1 Cross • The recessive traits reappeared! • Roughly 1/4 of the F2 plants showed a recessive trait

23. Explanation of the F1 Cross • The reappearance indicated that at some point the allele for shortness had been separated from the allele for tallness • Mendel suggested that the alleles for tallness and shortness in the F1 plants were segregated from each other during the formation of sex cells or gametes • When each F1 plant flowers, the two alleles segregate from each other so that each gamete carries only a single copy of each gene. Therefore, each F1 plant produces two types of gametes – those with the allele for tallness and those with the allele for shortness

25. Segregation • Segregation is the process of alleles separating from one another during gamete formation.

26. In Your Notebooks: 1a. What did Mendel conclude determines biological inheritance? 1b. What are dominant and recessive alleles? 1c. Why were true-breeding pea plants important for Mendel’s experiment? 2a. What is segregation? 2b. What happens to alleles between the P generation and the F2 generation? 2c. What evidence did Mendel use to explain how segregation occurs?