Inheritance of Traits: The Work of Gregor Mendel

1. What does the science of genetics study? 2. Why is Gregor Mendel called the Father of Genetics? 3. Why did Mendel chose pea plants for his experiments? a. b. c.

1. What does the science of genetics study? heredity: the passing of traits from one organism to its offspring 2. Why is Gregor Mendel called the Father of Genetics? 3. Why did Mendel chose pea plants for his experiments? a. b. c.

Gregor Mendel He became a Monk and then studied math and science. Born in 1822 in Austria. He became a Monk and then studied math and science. He was also in charge of the monastery garden, where he studied pea plants and their flowers. Pea flowers are made of Male and Female parts (M -pollen, F -eggs which get fertilized into seeds) Pea plants self-pollinate pollen fertilize the egg cells in the same plant. So, If a pea plant self-pollinates, what characteristics will the seed (and plant) inherit?

1. What does the science of genetics study? heredity: the passing of traits from one organism to its offspring 2. Why is Gregor Mendel called the Father of Genetics? His experiments with pea plants were the first to study heredity/ genetics 3. Why did Mendel chose pea plants for his experiments? a. b. c.

1. What does the science of genetics study? heredity: the passing of traits from one organism to its offspring 2. Why is Gregor Mendel called the Father of Genetics? His experiments with pea plants were the first to study heredity/ genetics 3. Why did Mendel chose pea plants for his experiments? a. grow and reproduce quickly b. c.

1. What does the science of genetics study? heredity: the passing of traits from one organism to its offspring 2. Why is Gregor Mendel called the Father of Genetics? His experiments with pea plants were the first to study heredity/ genetics 3. Why did Mendel chose pea plants for his experiments? a. grow and reproduce quickly b. have many different traits that can be studied at the same time c.

2 different characteristics for each trait Pea Plant Traits Seed Shape Flower Position Seed Coat Color Seed Color Pod Color Plant Height Pod Shape Round Wrinkled Yellow Green Gray White Smooth Constricted Axial Terminal Tall Short 2 different characteristics for each trait

1. What does the science of genetics study? heredity: the passing of traits from one organism to its offspring 2. Why is Gregor Mendel called the Father of Genetics? His experiments with pea plants were the first to study heredity/ genetics 3. Why did Mendel chose pea plants for his experiments? a. grow and reproduce quickly b. have many different traits that can be studied at the same time c. easy to breed through cross-pollination

4. What is pollination. What is self-pollination 4. What is pollination? What is self-pollination? What is cross-pollination?

4. What is pollination? Transfer of pollen from the male part of a flower to the female part of a flower What is self-pollination? What is cross-pollination?

4. What is pollination? Transfer of pollen from the male part of a flower to the female part of a flower What is self-pollination? One plant pollinates itself What is cross-pollination?

4. What is pollination? Transfer of pollen from the male part of a flower to the female part of a flower What is self-pollination? One plant pollinates itself What is cross-pollination? Transfer pollen from one plant to another

5. In the box below, label the drawing of a flower, including the stigma, style, ovary, anthers, filaments, pollen, petals, and sepals. petals Female part: Pistil Stigma Style Ovary (eggs) Male part: Stamen Anther Pollen (sperm) Filament sepals

6. What is meant by the term true-breeding 6. What is meant by the term true-breeding? Use pea plants as an example. 7. Mendel found that short pea plants were always true-breeding. Tall pea plants however are not always true-breeding. Sometimes crossing two tall plants produces offspring that are short. If you had several tall pea plants, how could you determine whether or not they were true-breeding?

6. What is meant by the term true-breeding 6. What is meant by the term true-breeding? Use pea plants as an example. A plant that always produces offspring that look like itself (i.e. a tall plant that always produces tall offspring) 7. Mendel found that short pea plants were always true-breeding. Tall pea plants however are not always true-breeding. Sometimes crossing two tall plants produces offspring that are short. If you had several tall pea plants, how could you determine whether or not they were true-breeding?

6. What is meant by the term true-breeding 6. What is meant by the term true-breeding? Use pea plants as an example. A plant that always produces offspring that look like itself (i.e. a tall plant that always produces tall offspring) 7. Mendel found that short pea plants were always true-breeding. Tall pea plants however are not always true-breeding. Sometimes crossing two tall plants produces offspring that are short. If you had several tall pea plants, how could you determine whether or not they were true-breeding? Allow tall plants to self-pollinate. If they produce only tall offspring, they are true-breeding. If they produce some short offspring, they are NOT true-breeding.

8. Mendel’s Experiment Plant Height T T t t T t T t T T T t T t t t P Generation F1 Generation F2 Generation Tall Short T T t t T t T t T T T t T t t t

9. What is the P1 generation? What is the F1 generation? F2?

9. What is the P1 generation? Parental generation What is the F1 generation? F2?

9. What is the P1 generation? Parental generation What is the F1 generation? First generation of offspring F2?

9. What is the P1 generation? Parental generation What is the F1 generation? First generation of offspring F2? Second generation of offspring

How did Mendel explain this occurrence? 9. What is the P1 generation? Parental generation What is the F1 generation? First generation of offspring F2? Second generation of offspring 10. What happened to the shortness trait during the F1 generation of Mendel’s experiment? How did Mendel explain this occurrence?

How did Mendel explain this occurrence? 9. What is the P1 generation? Parental generation What is the F1 generation? First generation of offspring F2? Second generation of offspring 10. What happened to the shortness trait during the F1 generation of Mendel’s experiment? It was hidden – all plants in F1 were Tt so they appeared tall even though they had a “t” (short) How did Mendel explain this occurrence?

9. What is the P1 generation? Parental generation What is the F1 generation? First generation of offspring F2? Second generation of offspring 10. What happened to the shortness trait during the F1 generation of Mendel’s experiment? It was hidden – all plants in F1 were Tt so they appeared tall even though they had a “t” (short) How did Mendel explain this occurrence? Must be two factors controlling each trait; 2 tall factors = tall, 2 short factors = short; 1 tall + 1 short factor = tall

Terminology Gene: sequence of DNA that codes for a trait Alleles: different forms of a gene Principle of dominance: dominant trait is always seen when dominant allele is present; recessive trait is only seen when no dominant allele is present Recessive allele: allele that is masked in phenotype when dominant allele is present Allele for blue eyes Dominant allele: allele that is always expressed in phenotype when it is present Allele for brown eyes

Notation When diagramming genetics experiments or solving genetics problems: A single letter of the alphabet is chosen to represent each trait (example: T) A capital letter represents the dominant allele (T). A lower case letter represents the recessive allele (t). Example: Pea plant height – T=tall, t=short

Pea Plant Traits Seed Shape Flower Position Seed Coat Color Seed Color Pod Color Plant Height Pod Shape Round Wrinkled Yellow Green Gray White Smooth Constricted Axial Terminal Tall Short

12. What is a hybrid? Can a short pea plant ever be a hybrid? Explain.

Hybrid: Organism with two different factors (alleles) for a trait (ex Hybrid: Organism with two different factors (alleles) for a trait (ex. T t) Example: Cross pollinate a true breeding red flower and a true breeding white flower. Seedlings=hybrid X =

Hybrid Cars Gas + Electric

8. Mendel’s Experiment Plant Height T T t t T t T t T T T t T t t t P Generation F1 Generation F2 Generation Tall Short T T t t T t T t T T T t T t t t

12. What is a hybrid? Organism with two different factors (alleles) for a trait (ex. T t) Can a short pea plant ever be a hybrid? Explain.

8. Mendel’s Experiment Plant Height T T t t T t T t T T T t T t t t P Generation F1 Generation F2 Generation Tall Short T T t t T t T t T T T t T t t t

12. What is a hybrid? Organism with two different factors (alleles) for a trait (ex. T t) Can a short pea plant ever be a hybrid? No Explain. Short factor is recessive – whenever tall factor is present, it will hide the short

13. Use a labeled, colored drawing to show what would happen if you crossed a true-breeding round-seed plant with a true-breeding wrinkled seed plant, and then crossed two of the F1 plants. Be sure to show the P, F1, and F2 generations.

13. Use a labeled, colored drawing to show what would happen if you crossed a true-breeding round-seed plant with a true-breeding wrinkled seed plant, and then crossed two of the F1 plants. Be sure to show the P, F1, and F2 generations. P X R R r r F1 X R r R r F2 R R R r R r r r

Mendel did his work before DNA! Pea Plant DNA (Electron Microscope)