1. 11-1 The Work of Gregory Mendel
Flora I

2. Genetics Genetics – the study of heredity
Essential to understanding biology

3. Mendel Mendel knew the following:
Each part of each flower produces pollen (anther)
Other portions produce female reproduction cells
The two join and fertilization occurs
Gametes – sex cell
Fertilization – male and female reproduction cells join to form a new cell
True-breeding – if allowed to self-pollinate, they would produce offspring identical to themselves

4. Genes and Dominance Mendel studied plant traits
Trait – specific characteristic of an organism
Ex: seed color, plant height, etc.
Mendel studied 7 traits:
Seed shape
Seed color
Seed coat
Pod shape
Pod color
Flower position
Plant height

5. Cont.
Mendel crossed plants with these seven contrasting traits and studied their offspring
Parents – called “P” generation
Offspring – called “F1” generation
A cross between parents with different traits are known as hybrids

6. Mendel’s Two Conclusions
Biological inheritance is determined by factors that are passed on from one generation to the next
These traits are called genes
Genes – sequence of DNA that codes for a specific protein thus determining the trait
Some genes have contrasting forms called alleles
Alleles – one of a number of different forms of a gene

7. Cont. Mendel’s Two Conclusions
The principal of dominance states that some alleles are dominant and others are recessive
An organism with a dominant allele for a specific trait will always exhibit that form of that trait.
Recessive alleles will only exhibit that trait when the dominant allele is absent
Ex: Mendel’s Experiment

8. Segregation
Did the alleles present in the P generation disappear from the F1 generation?
Mendel allowed 7 kinds of F1 hybrid plants to self-pollinate producing an F2 generation
See page 265

9. Law of Segregation
when any individual produces gametes, the copies of a gene separate, so that each gamete receives only one copy. A gamete will receive one allele or the other
Each F1 plant produces two types of gametes
Ex: Tt x Tt