11-1 The Work of Gregor Mendel

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A. Gregor Mendel’s Peas

• 1. Genetics is the scientific study of inheritance.

Listen to this story…..

• Once upon a time there were two cute white bunnies in the wild.

• The two bunnies fell in love and had many baby bunnies.

• …..but there was one thing that could not be explained….

Listen to this story…..

• …where did the gray bunny come from?

A. Gregor Mendel’s Peas

• 2. Mendel, an Austrian monk, studied genetics using pea plants.

A. Gregor Mendel’s Peas

• 3. Pea plants undergo fertilization (joining of male and female reproductive cells) when pollen (male reproductive cells) joins the female reproductive cells in the ovaries.

A. Gregor Mendel’s Peas

• 4. The pea plants at Mendels Monastery were true-breeding, allowed to self-pollinate, producing identical copies.

A. Gregor Mendel’s Peas

• Mendel wondered what would happen if he pollinated two different plants?

B. Genes and Dominance

• 1. Mendel studied 7 traits.• 2. Traits are specific characteristics that vary

from one individual to another. – Examples: Plant Color, Plant Height, Seed Texture

Activity Break!

• Identify which of the following 10 human traits you have by placing a check mark beside that trait.

• Compare the traits you have with other students in the classroom.

• FIRST, lets predict which traits are MOST common!

• Tongue Roller• Non-Tongue Roller• • Attached Earlobes• Unattached earlobes• • Dimples• No Dimples• • Right-handed• Left-Handed• • Widow's Peak• Straight Hairline

Left Thumb on top when Hands Crossed

• Right Thumb on top when Hands Crossed

• • Hair on mid-digit of hand• No hair on mid-digit of hand• • Bent little finger• Straight little finger• • Second toe longer than big toe• Second toe not longer than big

toe

B. Genes and Dominance

• 3. P= Parental Generation F= Filial Generation• 4. Offspring from parents with different traits

are called hybrids.

B. Genes and Dominance

• 5. The hybrids Mendel produced, surprisingly, only showed the traits of one of the parents.

B. Genes and Dominance

• 6. Mendel concluded that traits were passed on as units, called genes, that come in two forms, called alleles.

B. Genes and Dominance

• 7. The law of dominance states that some alleles are dominant and some alleles are recessive.

C. Segregation

• Do the recessive alleles disappear?!?!?!• Mendel Tested that too!!!!

C. Law of Segregation

• 1. Mendel crossed Filial one (F1) plants to each other to produce Filial two (F2) plants.

C. Segregation

• 2. Mendel suggested that during gamete formation (MEIOSIS), the alleles separate into different cells.

C. Segregation

• 3. The law of segregation states that alleles segregate (separate) from each other so that each gamete only carries one copy of each gene.