1. Life Science
Genetics

2. The study of heredity started with the work of Gregor Mendel and his
pea plant garden
Mendel was an Austrian Monk that lived
in the mid 1800’s

3. Mendel noted that the size of pea plants varied
Mendel noted that the size of pea plants varied. He cross-bred these pea plants to find some surprising results.

4. Mendel’s cross between tall pea plants yielded all tall pea plants
Mendel’s cross between tall pea plants yielded all tall pea plants. His cross between small pea plants yielded all small pea plants. X = X =
Mendels’ cross between tall pea plants and small pea plants yielded all tall pea plants. x =

5. Mendel then crossed these second generation tall pea plants and ended up with 1 out 4 being small.x =

6. Mendel’s work led him to the understanding that traits such as plant height are carried in pairs of information not by single sets of information.
-Carrying the information are chromosomes. -Chromosomes are made up of sections called genes Genes are made up of DNA

8. DNA D.N.A. - Deoxyribonucleic Acid Molecule made of: 1. Deoxy Sugar
2. Combination of four nitrogen bases
Either: a. Guanine
b. Cytocine
c. Thymine
d. Adenine
The sum total of combinations that these four bases are capable of creating are greater than all the stars visible in the night time sky

9. DNA Nitrogen bases pair up Pairing creates a ladder shape
Cytosine & Guanine
Thymine & Adenine
Pairing creates a ladder shape
Angle of bonds creates a twist
Ladder and Twist produces the famous
“Double Helix”

10. DNA DNA resides in all cells Each strand forms a chromosome
Nucleus
Cell
DNA resides in all cells
Inside the nucleus
Each strand forms a chromosome
DNA

11. DNA DNA is found in all living cells
It controls all functions inside a cell
It stores all the genetic information for an entire living organism
Single cell like an amoeba
Multi cell like a human

12. Genetics
Small sections of DNA are responsible for a “trait”. These small sections are called “Genes”.
Gene - A segment of DNA that codes for a specific trait
Trait - A characteristic an organism can pass on to its offspring through DNA
Gene

13. Genetics There are three basic kinds of genes:
Dominant - A gene that is always expressed and hides others
Recessive - A gene that is only expressed when a dominant gene isn’t present
Codominant - Genes that work together to produce a third trait

14. Genetics
So, back to the original question. What color hair will the offspring of Prince Charming and Snow White have?

15. Co-dominance
Hair color is different from widows peak, no color is truly dominant.
Brown and blond are the two, true traits
Homozygous conditions produce either brown or blond hair
Heterozygous conditions produce red hair

16. Genetics
For Snow White to have brown hair she must be homozygous dominant, “BB”, a blond Prince Charmin must be homozygous recessive, “bb”.
All the offspring from Prince Charming and Snow White will therefore be heterozygous, “Bb”, and since hair color is co-dominant….. all their children will have red hair B B b Bb Bb b Bb Bb