1. Chapter 8 Section 1: The Origins of Genetics Grade 10 Biology Spring 2011

2. Bell Ringer Make a list of 5 characteristics that are passed on in families Name one characteristic that may also be inherited but that is also influenced by behavior or environment

3. Objectives Identify the investigator whose studies formed the basis of modern genetics List characteristics that make the garden pea a good subject for genetic study Summarize the three major steps of Gregor Mendel’s garden pea experiments Relate the ratios that Mendel observed in his crosses to his data

4. Mendel’s Studies of Characters Heredity: the passing of characters from parents to offspring

5. Mendel’s Breeding Experiments Gregor Mendel: grandfather of genetics Carried out experiments with the garden pea plant Genetics: the branch of biology that focuses on heredity

6. Mendel’s Breeding Experiments T.A. Knight ◦ Crossed a variety of the garden pea that had purple flowers with a variety that had white flowers ◦ All of the offspring of Knight’s crosses had purple flowers ◦ When 2 of the purple flowered offspring were crossed, their offspring showed both white and purple flowers ◦ White trait had reappeared

7. Mendel’s Breeding Experiments Mendel’s experiments differed because he counted the number of each kind of offspring and analyzed the data

8. Useful Features in Peas Several characters of the garden pea exist in two clearly different forms ◦ Character = inherited characteristic, such as flower colour ◦ Trait = refers to single form of a character, such as purple flowers

9. Useful Features in Peas Male and female parts of a garden pea plant are enclosed within the same flower ◦ Can control mating Small, grows easily, matures quickly, and produces many offspring

10. Traits Expressed as Simple Ratios Monohybrid cross: cross that involves one pair of contrasting traits True breeding: all of offspring would display only one form of the character ◦ Done by allowing a variety of peas to self pollinate for several generations P Generation: first two individuals that are crossed in a breeding experiment

11. Traits Expressed as Simple Ratios F1 Generation: the offspring of the P generation F2 Generation: the offspring of the F1 generation

12. Mendel’s Result F1 generation  showed only one form of the trait F1 generation allowed to self-pollinate Missing trait reappeared in the F2 generation

13. Mendel’s Result F2 Generation: ◦ 705 purple ◦ 224 white ◦ 705:224 or 705/224 ◦ Reduced = 3:1 He found the same results for each of the other 7 traits he studied