Mendel and His Peas

Why don’t you look like a rhinoceros?

The answer to this question seems simple: Neither of your parents is a rhinoceros. But there is more to this answer than meets the eye.

How are traits passed from parents to offspring?

Do You Agree or Disagree? Like mixing paints, parents’ traits always blend in their offspring. If you look more like your mother than you look like your father, then you received more traits from your mother. All inherited traits follow Mendel’s patterns of inheritance.

Early Ideas About Heredity Heredity is the passing of traits from parents to offspring. - Gregor Mendel is known as the father of genetics — the study of how traits are passed from parents to offspring.

May Be More Complicated Than You Think! -You might have curly hair, while both of your parents have straight hair. -You might have blue eyes even though both of your parents have brown eyes. HOW DOES THIS HAPPEN?!

https://www.youtube.com/watch?v=QmSJGhPTB5E

Gregor Mendel (1822-1884) The Father of Genetics Mendelian Genetics 4/19/2017 Gregor Mendel (1822-1884) The Father of Genetics This has been modified from the original ppt Oct. 2011 copyright cmassengale

Gregor Johann Mendel Austrian monk Mendelian Genetics 4/19/2017 Gregor Johann Mendel Austrian monk Studied the inheritance of traits in pea plants Developed the laws of inheritance Mendel's work was not recognized until the turn of the 20th century

https://www.youtube.com/watch?v=Mehz7tCxjSE&feature=share

Mendel's Experimental Methods Mendel studied genetics by doing controlled breeding experiments with pea plants. There are two types of pollination: self-pollination cross-pollination

Think-Pair-Share What do you think the difference is between self-pollination and cross-pollination?

Self Pollination

Mendel's Experimental Methods (Con) When a true-breeding plant self-pollinates, it always produces offspring with traits that match the parent. Mendel cross-pollinated pea plants himself and recorded the traits that appeared.

Cross-Pollination Gregor removed the anthers of the plants to make sure they did not self-pollinate.

Mendel’s Results Once Mendel had enough true-breeding plants for a trait he wanted to test, he cross-pollinated selected plants. Plants are called hybrids if they come from true-breeding parent plants with different forms of the same trait.

He Studied: - seed shape - plant height flower color 7 characteristics

First Generation Crosses Purple Flowers + White Flowers = ALL PURPLE Look on page 407 in textbook.

Second Generation Hybrid Crosses Mendel also cross-pollinated hybrid plants. He observed that offspring of hybrid crosses always showed traits in a 3:1 ratio.

Second Generation Hybrid Crosses

Mendel’s Results (Cont) Mendel recorded traits of offspring from many hybrid crosses.

Mendel’s Conclusions Mendel concluded that two factors, one from each sperm and one from each egg, control each inherited trait.

Mendel’s Conclusions (cont) A dominant trait is a genetic factor that blocks another genetic factor. A recessive trait is a genetic factor that is blocked by the presence of a dominant factor.

Review Question 1 What method did Mendel use to select which plants pollinated other plants? True breeding Self-pollination Cross- pollination bees

C

Review Question 2 What is the approximate ratio of dominant to recessive expression when both parents are hybrid? 1 : 1 2 : 1 3 : 1 4: 1

C

Class Work What is the difference between genetics and heredity? 2) Describe Mendel’s first set of experiments. 3) Describe Mendel’s second set of experiments. 4) Why do you think Mendel chose to study pea plants? 5) In cats, there are two types of ears: normal and curly ears. A curly-eared cat mated with a normal-eared cat, and all of the kittens had curly ears. Are curly ears a dominant or recessive trait? Explain.