Chapter 11 Introduction To Genetics

History ► Gregor Mendel…1882 ► Austrian monk ► In charge of the monastery’s garden ► Experimented with pea plants ► “Pollinated” Pea Plants

How Did Mendel Pollinate the Pea Plants?? ► First we must learn about: how plants reproduce sexually 1) the organs of seed plants 1) the organs of seed plants 2) types of seed plants 2) types of seed plants 3) how plants reproduce sexually 3) how plants reproduce sexually 4) what is in a seed 4) what is in a seed

Two Types of Seed Producing Plants ► Gymnosperms Angiosperms a) Cone producing Flower producing plants plants plants plants b) Have: Have: roots roots roots roots stems stems stems stems leaves/needles leaves leaves/needles leaves flowers flowers

Mendel ► Since pea plants produce flowers, we will discuss the organs of these plants ► What is the function of: a) the root? a) the root? b) the stem? b) the stem? c) the leaf? c) the leaf? d) the flower d) the flower

Function of the Flower ► To attract insects ► Sexual reproduction for the plant To produce offspring that contain the genes from both parents To produce offspring that contain the genes from both parents

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Parts of the Flower ► Stamen…..male…produces “Pollen” which is a case that has the sperm ► Carpal…..female..produces the “Egg” in the “Ovary” ► Petals…..attract the insects for “Pollination” ► Sepal….protects the “Bud” of the flower before it blooms

Pollination

Mendel Used A Paint Brush

What Happens When The Pollen Lands on the Female Part of the Flower?

The Seed ► Result of Fertilization ► Seed Contains Three Major Parts a) the “embryo” a) the “embryo” b) “food” for the embryo until the seedling b) “food” for the embryo until the seedling breaks through the soil and forms its breaks through the soil and forms its first leaves first leaves c) “seed coat” protects the seed c) “seed coat” protects the seed

The Seed

Germination of a Seed

Traits of Mendel’s Pea Plants Page 264

Mendel ‘s Crosses ► He obtained the pollen from a tall pea plant and placed the pollen on the female part of a short pea plant ► RESULT ???....all tall ► Where did the short trait go?

He Crossed the first Generation ► 75% tall and 25% short for the second generation ► Mendel concluded that the short trait was “hidden” in the first generation and appeared in the second generation

Mendel’s Hypothesis ► Remember in 1882 chromosomes and DNA were not discovered ► Mendel Hypothesized 1) A “Trait” is passed on from generation to generation 2) Traits must occur in pairs since in the first generation the short trait was hidden by the tall trait

Mendel Hypothesizes ► 3) One trait can be “Dominant” over another trait “Recessive” ► Mendel’s hypothesis developed the principle which states “ some “Alleles” are dominant and other alleles are recessive ► An “allele” is a different form the the same trait

Trait…Eye Color ► Alleles for eye color: a) gray a) gray b) blue b) blue c) brown c) brown d) hazel d) hazel e) green e) green

Law of Segregation