1. Mendel and the gene idea
Founder of Modern Genetics
Mendel and the gene idea

2. What Is heredity
The passing on of characteristics from parents to offspring
Trait
physical characteristic
Genetics
is the study of heredity

3. Patterns of Inheritance
Gregor Mendel
( ) is the called the “Father of Genetics”
Researched with garden peas
Developed the ideas that are the basis of genetics

4. Mendel used peas…
Characters (inherited characteristic) are in two distinct forms (such as white and purple color) called traits.
Not many traits
Easy to keep track
The male and female gametes are enclosed within the same flower – He could control the fertilization process
Self-fertilization
Cross-pollination
The garden pea is small, grows easily, matures quickly and produces many offspring.

5. Mendelian genetics Height - short or TALL Seed color - green or YELLOW
Mendel studied a number of characteristics in pea plants including:
Height - short or TALL
Seed color - green or YELLOW
Seed shape - wrinkled or ROUND
Seed coat color - white or GRAY
Pod shape - constricted or SMOOTH
Pod color - yellow or GREEN
Flower position - terminal or AXIAL

6. questions What did Mendel cross? What are traits? What are gametes?
What is fertilization?
What is heredity?
What is genetics?

7. Chromosome Logical Structure
Gene – segments of DNA that code for the basic units of heredity and are transmitted from one generation to the next
Allele – genes that reside at the same locus on homologous chromosomes
Alleles are the result of mutation!!!!!!

8. genotype Genotype Gene(s) responsible for the trait
The alleles that are present on each homologous chromosome that code for the trait

9. Phenotype Phenotype Expression of the characteristic The trait
The way we “look”
Red hair or Brown hair
The expression of the gene

10. Predicting Outcomes-probability
The likelihood that a specific event will occur
Probability = # of one kind of possible outcome
total # of all possible outcomes
a coin lands on “heads”
1 outcome
Total possible outcomes
= 2
heads or tails
Possibility that the coin will land on heads = 1/2

11. Genotypes Phenotypes
At each locus (except for sex chromosomes) there are 2 genes. These constitute the individual’s genotype at the locus. The alleles that are present.
The expression of a genotype is termed a phenotype. For example, hair color, weight, or the presence or absence of a disease.

12. Mendel was a careful researcher
Carefully controlled experiments
Studied one trait at a time
Kept detailed data
Cross - combining gametes from parents with different traits
The offspring are called hybrids
offspring of parents with different traits
A monohybrid cross is one that looks at only one trait (let’s look at plant height – tall or short)
Cross fertilization
Pollen from one plant to fertilize another plant

13. Mendel’s monohybrid crosses
Step One:
Mendel allowed the peas to self-pollinate for several generations.
What Did Mendel Find?

14. Mendel’s monohybrid crosses
Step One:
Each variety was true-breeding for a particular character.
tall plants only produced tall plants
These plants served as the parental generation.
The P generation is the first two individuals that are crossed in a breeding experiment

15. Mendel’s monohybrid crosses
Step Two:
Mendel cross-pollinated two P generation plants with different traits
The offspring were the first filial generation or F1 generation
Mendel recorded the traits of the offspring
What Did Mendel Find?

16. Mendel’s monohybrid crosses
Tall plant crossed with short plants produced all tall offspring
Purple flowers crossed with white flowers produced all purple offspring

17. Mendel’s monohybrid crosses
Step Three:
Finally, Mendel allowed the F1 generation to self-pollinate.
He called the offspring of the F1 generation, the second filial generation, or F2 generation
Again, Mendel recorded the traits of the offspring
What Did Mendel Find?

18. Mendel’s monohybrid crosses
Mendel found that 3 out of 4 (¾) of the offspring were tall & 1 out of 4 (¼) were short
(the short plants reappeared!!!!!!)

19. Mendel’s monohybrid crosses
Mendel found the same 1:3 ratio (1 out of 4) in the other traits as well!

20. Mendel’s results
He discovered different laws and rules that explain factors affecting heredity