1. Mendelian Genetics

4. It began with Gregor Mendel
He was an Austrian Monk who experimented with garden peas in the Mid 19th Century
He noticed certain traits seemed to be passed from one generation to another
He is known as the “father of genetics”

5. The father of what? Genetics is the study of heredity
Heredity is the passing of traits from parents to offspring

6. What did Mendel work with?
Mendel worked with peas
He chose peas because they grew quickly, he could control how they reproduced, and the traits were easy to observe.

7. Austrian Monk
150 yrs ago
“Father of Genetics”
Pea plants because they grew quickly, were easy to observe, and he could control their reproduction

8. What was Mendel looking for?
Mendel noticed how certain TRAITS were passed from generation to generation
Traits are specific characteristics of an organism

9. Some of the traits Mendel studied were height, flower color, seed shape and color, pod shape and color and flower position.

10. Seed shape
Seed color
Seed coat color
Pod shape
Pod color
Flower position
Stem height
Austrian Monk
150 yrs ago
“Father of Genetics”
Pea plants because they grew quickly, were easy to observe, and he could control their reproduction

11. P generation F1 generation F2 generation
Parents
F1 generation
children
Mendel did several crosses
He called the first line of crosses the P generation
P stands for Parent
The offspring of the P generation were called the F1 generation
F1 stands for First Filial, meaning 1st son
When he crossed plants from the F1 generation, he called the offspring the F2 generation or 2nd son generation
F2 generation
grandchildren

12. Purebred purple X Purebred white = F1 generation
Mendel’s Crosses
Mendel’s P generation were PUREBRED plants
Purebred plants are those that have been self-pollinated for a long time and have become GENETICALLY UNIFORM
He crossed 2 types of purebred plants
Purebred purple X Purebred white = F1 generation

13. Mendel’s Crosses
Mendel then allowed members of the F1 generation to cross to produce the F2 generation
The F2 generation included purple flowers and white flowers

14. Seed shape Seed color Seed coat color Pod shape Pod color
Flower position
Stem height
Austrian Monk
150 yrs ago
“Father of Genetics”
(parental)
Purebred Tall x Purebred Short
(kids) = All Hybrid Tall
Then cross 2 F1 plants
Hybrid Tall x Hybrid Tall
(grandkids)= 1 Pure Tall, 2 Hybrid Tall, 1 Pure Short
¾ tall and ¼ short
Pea plants because they grew quickly, were easy to observe, and he could control their reproduction

15. Mendel found that these traits were linked to factors that are passed from generation to generation
Today, we call these factors GENES
Genes can have different forms called ALLELES
For example, Height Gene has 2 forms, tall and short

16. bb Mendel’s Laws b Genes control traits Genes exist in pairs (alleles)
Law of Segregation
There are different forms of each trait called alleles.
Parents have both alleles.
Their sex cells will have one copy of each allele.
Dad has blue eyes bb b
Each Sperm has one allele
Body cell

17. Principle of Dominance
Mendel concluded that some alleles are dominant and others are recessive
As long as the dominant allele is present, then it will show up
The recessive allele will only be seen if a recessive allele is inherited from each parent
In other words, you must have 2 recessive alleles to see them

18. = Principles of Genetics
Seed shape
Seed color
Seed coat color
Pod shape
Pod color
Flower position
Stem height
Austrian Monk
150 yrs ago
“Father of Genetics”
(parental)
Purebred Tall x Purebred Short
(kids) = All Hybrid Tall
Then cross 2 F1 plants
Hybrid Tall x Hybrid Tall
(grandkids)= 1 Pure Tall, 2 Hybrid Tall, 1 Pure Short
¾ tall and ¼ short
Pea plants because they grew quickly, were easy to observe, and he could control their reproduction
Controlled by alleles which are different forms of a gene (mom/dad)
Always expressed when the allele
is present
Is hidden whenever the dominant allele is present.
= Principles of Genetics
Individual factors (genes) must control inheritance of traits
These genes exist in pairs known as alleles. You get one from your mom and one from your dad
One gene in a pair can mask the other gene (dominant and recessive)

19. ALLELES
Since alleles are inherited from each parent, they can be the same or different
If an organism inherits 2 of the same alleles, it is said to be HOMOZYGOUS (true breeding) for that trait
If an organism inherits 2 different alleles, it is said to be HETEROZYGOUS (hybrid) for that trait

20. Putting it all Together…
GENOTYPE (HETEROZYGOUS) Tt =
Tall
ALLELE
ALLELE
PHENOTYPE

21. A punnett square can calculate the probability that offspring with a certain combination of alleles will be produced.
Crossing 1 trait at a time
For example, Mendel crossed a pure tall plant with a pure short plant
For these crosses, we use a PUNNETT SQUARE
This is a grid designed by Reginald Punnett to keep track of the alleles

22. Punnett Square
Parent 2 – Pure Tall
F1 Generation
Parent 1- Pure Short

24. FINAL COUNTDOWN Name one name that Gregor Mendel is known by
Name 2 reasons Mendel liked to work with pea plants
Name 3 principles of genetics that
Mendel discovered