7th Grade Science

Chapter 5 Notes 

I.                 Mendel and His Peas

Heredity-passing of traits from parent to offspring

A.Who Was Gregor Mendel?

Monk in Austria/worked in monastery gardens

B. Unraveling the Mystery

Patterns of inheritance not always clear

Studied pea plants

1. Self-Pollinating Peas

Pea plants-grow quickly, different traits to study, could self pollinate

True-breeding=all offspring like parent

Cross-pollination=1 plant fertilizes another

2. Characteristics

Feature with different  forms in a population

Ex-hair color, eye color, vision

Trait-different forms of a characteristic

Ex-brown hair, blue eyes, near-sightedness

3. Mix and Match

Cross-pollinated plants with different traits

Ex-purple flowers with white flowers

C. Mendel’s 1^st Experiments

1^st generation-parent gen

1^st gen of offspring-1^st generation or f1

Traits that always showed-dominant

Traits that disappeared and reappeared-recessive

D.                        Mendel’s 2^nd Experiments

Recessive trait reappears in 2^nd gen

1. Ratios in Mendel’s Experiments

Ratio of dominant to recessive- 3 to 1

2. Gregor Mendel-Gone but Not Forgotten

Mendel’s work not recognized until 30 yrs after death

Mendel’s Laws of Heredity

1.  Mendel’s Law of Segregation.   

Get 1 trait from both parents

2. Law of Independent Assortment

Get a mixture of traits from both parents