Chapter 11

Introduction to GeneticsINB pg 131

Who was Gregor Mendel?• He was known as the “FATHER OF

GENETICS” • He discovered how traits were inherited

GENETICS – study of heredity

HEREDITY – the passing of traits from parents to offspring

Mendel’s Peas• Mendel did his study on pea plants• Pea plants have many traits

(tall/short, purple flowers/white flowers)

• Pea plants can beself-fertilized or cross-fertilized

Types of Plants

1.True-Breeding - these plants always create plants that look like themselves

2.Hybrids – offspring of true-breeding plants

Tall x Short = Hybrid

DominanceSome traits are dominant over others.

Tall x Short = all tall offspring (hybrids)

•Tall is the dominant trait • (represented by a capital letter “T”)

•Short is recessive • (represented by a lowercase letter “t”)

Genes and Alleles

Mendel discovered that each trait is controlled by two factors (alleles)

Genes – factors that determine your traits

NOT THESE JEANS!

Mendel’s Experiments

Draw the crosses

Gen 1 Smooth and wrinkled

Gen 2 offspring of gen 1 crossed

Explaining the Cross

When a parent makes sperm or eggs, their genes separate        (PRINCIPLE OF SEGREGATION)

The GAMETES (egg or sperm) contain either a T allele (tall) or a t allele (short)

GENOTYPE  -  what genes, letters, the organism has (TT, Tt, tt)

PHENOTYPE   - what it looks like (tall or short)

Let's review what you know about genetics......

Check for understanding

1.  A one-eyed purple people eater is crossed with a two eyed purple people eater.  All of their offspring have two eyes.   Which trait is dominant?

2.  If you use the letter E for this gene.   What is the genotype of the offspring?      Are these offspring the F1 or F2 generation?

4.  If you crossed the offspring with each other?  How many ofthe new offspring would you expect to have two eyes?

More checking

5.   The passing of traits from parents to offspring is known as  ___________________________

6.  Who was the father of genetics?  __________

7.  A single gene will code for a _______________, such as flower color.

8.  Every gene is made of two ______________