Gregor Mendel 1822 1884 n n Augustinian monk

Gregor Mendel (1822 -1884) n n Augustinian monk who taught natural science to High school students. He was born in Moravia, Czech Republic Mendel was a brilliant youngster but his family was very poor!! So, he entered an Augustinian monastery to continue his education and start his teaching career.

Planting the Seeds of Genetics n Between 1856 and 1863 Mendel patiently cultivated and tested at least 28, 000 pea plants n He studied analyzed the shape of seed, color of seed, tall stemmed and short stemmed, and tall plants and short plants n All of these are called: Traits

Gregor Mendel n Came up with the basic laws of Heredity n Mendel's work became the foundation for modern Genetics. n Many diseases are known to be inherited n He found actual proof of the existence of Genes n At that time no one knew what genes were

Traits What is a Trait? A physical, visible characteristic Example: Pea shape, pea color……. n Dominant : trait shows up in an offspring (You can actually see it) n Recessive trait is masked by dominant trait n (You can’t see the recessive trait, but it is present in the organisms) n

Heredity and Genetics What is Heredity? The passing of traits from parents to their offspring or children n What is Genetics? The Scientific study of Heredity n Gregor Mendel is known as………? n The Father of Genetics

- Mendel’s Work Mendel’s Experiments n In all of Mendel’s crosses, only one form of the trait appeared in the F 1 generation. However, in the F 2 generation, the “lost” form of the trait always reappeared in about one fourth of the plants. n o i t a r e P Gen F 1 Generation F 2 Gen eration

Mendel’s Pea pod experiment Parent First Peas Gene ratio All o n or F yello f the offsp 1 : w r ! i Wha ng we Men greendel! Whet a surprisre peas re are e for ? ? the Secon d Gen 3 offs eratio pring n or F 1 offs were 2 pring yellow : was g ree n

Genes and Alleles What is a Gene? A factor that controls a specific trait Example: Gene for hair color, eye color, pea color…. n Is gene a piece or segment of DNA? Yes it is!! n So, what is an Allele? Different form of a gene Example: Allele for hair color can be: Black hair, Brown hair or Blonde hair n

Dominant and Recessive Alleles What is an Allele? * A trait controlled by a specific gene: Example: Hair color Eye color Height Body shape n Each trait has 2 alleles: 1. One allele from the Mother 2. Second allele from the Father n

Dominant and Recessive Alleles Dominant allele * The allele you can see * Covers up or masks the recessive allele n Recessive allele * Only shows if dominant allele is not present * Both alleles have to be recessive n

Genetics of Pea Plants 1. How many traits did Mendel Study? Seven 2. What is the Recessive allele for Pod Color? Yellow 3. Is the yellow seed controlled by dominant or recessive allele? Dominant 4. For all of the alleles, which color is recessive? Yellow 5. Which seed shape is Dominant Round

Mendel’s Crosses What is a Purebred plant? * Plant (or any organism) that produces same form of trait as the parent * Both alleles are either: a. Dominant – Tall plant b. Recessive - short plant n What is a Hybrid Plant? * Plant that has one dominant and one recessive allele for a trait n

Using Symbols in Genetics To represent or show alleles what do scientists use? Answer: They use letters n What type of letters are used to show a Dominant allele? Answer: Uppercase letters TT BB MM n What type of letters are used to show a recessive allele Answer: Lower case letters aa mm tt n

Mendel’s Pea pod experiment

Mendel’s Pea pod experiment n Yellow Pea = Dominant n Green Pea = Recessive n First Generation or F 1: All peas are Yellow or Dominant Trait n Second Generation or F 2: Three peas are yellow one pea is green Ratio is 3: 1

First generation of F 1 and Second generation or. F 2

First Generation or F 1: n What are the colors of the parents in the First generation? Answer: One parent is white the other purple n Which color is Dominant in the offspring? Answer : Purple flower “Ww” is Dominant

First Generation or F 1: n Which color is recessive? Answer: White flower “ww” is Recessive n So, in F 1 generation what color are all of the offspring? Answer: All 4 offspring are Dominant Purple “Ww”

Second Generation or F 2: n What color are the parents in the Second Generation or F 2? Answer: Both parents are Purple – Ww n Why are the parents purple even when they have the white allele? Answer: Because the purple color allele is Dominant/covers up the recessive white color allele

Second Generation or F 2 n n n How many offspring are Purple? Answer: Three offspring are Purple Ww What color is the 4 th offspring? Answer: The offspring is white What is the ratio of colors in the Second Generation? Answer: The ratio in the second generation is 3 purple : 1 white 3: 1

Mendel’s Recognition n In 1900 Mendel's work was finally recognized by three independent investigators. n One of these being the Dutch botanist, Hugo De Vries. n But it was still not until the early 1920 s and early 1930 s that the full significance of his work was recognized particularly how it related to Evolution of organisms

Review questions 1. Where was Gregor Mendel born? Answer: In Czech Republic 2. How many pea plants did he study? Answer: Around 28, 000 3. What is an allele? Answer: A trait controlled by a specific gene 4. What is a dominant allele? Answer: An allele or trait that always shows up if it is present in the organism 5. What is a recessive allele? Answer: An allele or trait that is masked by the dominant allele (Can’t see the trait)

6. Why do we have 2 alleles for the same trait? Answer: One from mom and one from dad 7. What letter combinations can you use to show a dominant trait? A recessive trait? Answer: Dominant: BB or Bb Recessive: bb 8. What did Gregor Mendel study? Answer: Pea Plants 9. How many traits in peas did Mendel study? Answer: Seven 10. What is Gregor Mendel called? Answer: The Father of Genetics

Using Symbols in Genetics n n Dominant Allele: a. Represented by a Capital letter b. Brown or “B” eye color is dominant over blue or “b” eye color Recessive Allele: a. Represented by lower case letter b. Blue or “b” eye color is recessive or masked by Brown or “B” eye color Brown eyes can have these allele combinations BB or Bb Blue eyes can only have this combination bb