1. 14-1 The Work of Gregor Mendel

2. Objectives
Explain how genotypes (heterozygous and homozygous) contribute to phenotypic variation within a species.
Predict the probability of the occurrence of specific traits, including sex-linked traits, in an offspring by using a monohybrid cross.

3. Introduction
Can you read the number?

4. Introduction
Can you read the number?

5. Introduction
Can you read the number?

6. Gregor Mendel’s Peas
Austrian monk considered the “father of genetics”.
Genetics – the study of heredity.

7. Gregor Mendel’s Peas Noticed pea plants had different traits:
Tall vs. short
Green vs. yellow
Wanted to figure out why the peas had different traits.
Make signs…

8. Pg. 264 Gregor Mendel’s Peas
Mendel started with pure true-breeding peas.
True-breeding – produces identical offspring.
Mendel-cross pollinated peas with different traits.
Ex. Tall & short plants
Crossed seven different traits.
Make signs…
Pg. 264

9. Objectives
Explain how genotypes (heterozygous and homozygous) contribute to phenotypic variation within a species.
Predict the probability of the occurrence of specific traits, including sex-linked traits, in an offspring by using a monohybrid cross.

10. Review Who is this guy? He’s credited with being the “father of ____.”
What plant did he work with?

11. Vocabulary Trait – a specific characteristic.
Hybrid – the offspring of crosses between parents with different traits.

12. P Generation  F1 Generation 
What Did Mendel Do?
He produced three generations of pea plants.
The original parents were known as the “P (parental) Generation”.
The offspring of the P generation were known as the “F1 Generation”.
The offspring of the F1 generation were known as the “F2 Generation”.
P Generation  F1 Generation 
F2 Generation

13. Tall Medium Short Genes and Dominance
Let’s take pea plant height for example for the P generation…
Tall
Medium
Short

14. Genes and Dominance
The F1 generation was ALL TALL (pg. 265).
Pg. 264

15. Genes and Dominance
The F2 generation had three tall plants and one short…

16. Genes and Dominance From this Mendel concluded two things:
Inheritance is determined by “factors” passed down generations.
Start with these…

17. More Vocabulary Gene – chemical factors that determine traits.
Allele – different forms of a gene.

18. Genes and Dominance From this Mendel concluded two things:
Inheritance is determined by “factors” passed down generations.
Some alleles are dominant and others are recessive (principle of dominance).
Start with these…

19. Tt Genes and Dominance How does dominance work???
An organism with a dominant allele will ALWAYS show for that form of the trait.
Example:
Gene
Allele
Dominant Allele
Recessive Allele
What would this pea plant be…short or tall? Tt

20. Genes and Dominance
So…what trait would the following have? TT tt Tt

21. Segregation
Mendel wanted to what happened to the recessive allele in the F1 cross to produce the F2 generation . F2 F1

22. What do we call gamete formation?
Segregation
Segregation – the splitting of alleles during gamete formation.
Segregation – the splitting of alleles during meiosis.
What do we call
gamete formation?

23. Review and Closure We’ll talk more about these things later this week.
Have a great Spring Break
Come back ready to work on research project.