1. 11-1: The Work of Gregor Mendel
Biology 2

2. GENETICS: scientific study of heredity
Introduction
Every living thing has a set of characteristics inherited from its parent(s)
Scientists have discovered that heredity helps understand what makes species unique
GENETICS: scientific study of heredity

3. Became a priest and teacher at monastery
Gregor Mendel
Gregor Mendel was born in 1822 in Czech Republic
Became a priest and teacher at monastery
Studied math and science at University of Vienna
Was in charge of monastery garden

4. Mendel was interested in monastery garden peas
Gregor Mendel
Mendel was interested in monastery garden peas
He knew that parts of flowers contain male/female sex cells
Stamen produce pollen (Sperm)
Pistil produce ovules (Egg)

5. Gregor Mendel
FERTILIZATION: process in sexual reproduction in which male and female reproductive cells join to form a new cell
Pea plant flowers are normally self-pollinating
Pollen fertilizes ovule of same flower

6. All the plants that Mendel took care of were true-breeding
Gregor Mendel
Seeds that are produced by self-pollination inherit all their characteristics from the one parent (true-breeding!)
All the plants that Mendel took care of were true-breeding

7. Gregor Mendel
TRUE-BREEDING: term used to describe organisms that produce offspring identical to themselves if allowed to self-pollinate
In true-breeding, one set would produce only tall plants; one set would produce only purple flowers; etc…

8. Mendel wanted to produce seeds from different plants
Gregor Mendel
Mendel wanted to produce seeds from different plants
He had to prevent self-pollination
He did this by removing the stamen from flowers
Used the removed stamen to fertilize other flowers, called cross-pollination
Allowed Mendel to study different characteristics

9. ALLELES: one of a number of different forms of a gene
Genes and Dominance
TRAIT: specific characteristic that varies from one individual to another
Mendel studies 7 different pea plant traits
Each of the 7 traits had 2 different “looks” – now called alleles
ALLELES: one of a number of different forms of a gene

10. Offspring are called F1 (first filial)
Genes and Dominance
Original plants used for fertilization are called P (parental) generation
Offspring are called F1 (first filial)
Filial = Latin word for son/daughter

11. HYBRID: offspring of crosses between parents with different traits
Genes and Dominance
HYBRID: offspring of crosses between parents with different traits
After creating hybrid F1 offspring, Mendel studied what the plants looked like
Mendel noticed that offspring had characteristics of only 1 parent
Other parent characteristics “disappeared”

12. Genes and Dominance
Pg 148
Mendel learned 2 things from his experiments:
Biological inheritance is determined by factors that are passed from one generation to the next
These factors are now called genes
GENES: sequence of DNA that codes for a protein and thus determines a trait

13. dominant allele will always show dominant trait
Genes and Dominance
Principle of dominance states that some alleles are dominant and others are recessive.
dominant allele will always show dominant trait
Recessive allele will only show if there is no dominant allele

14. Mendel wanted to know if the recessive trait disappeared
Segregation
Mendel wanted to know if the recessive trait disappeared
Allowed all 7 hybrid F1 offspring to produce an F2 generation
In F2 generation, recessive showed up again!
Figured out that the stronger (dominant) allele “covered up” the weaker (recessive) allele

15. SEGREGATION: separation of alleles during gamete formation
When sex cells (gametes) are created, dominant and recessive alleles have to “separate” from each other
GAMETES: specialized cell involved in sexual reproduction

16. Section Assessment
____________: process in sexual reproduction in which male and female reproductive cells join to form a new cell
What does true-breeding mean?
What 2 things did Mendel learn from his experiments?

17. Mendel – From the Garden to the Genome