1. Genetics
The study of Heredity

2. Mendel and His Peas
Gregor Mendel 1860’s monk that discovered the fundamental principles of genetics by breeding garden peas.

3. Mendel cross-pollinated pea plants
He cut away the male parts of one flower, then dusted it with pollen from another

4. Mendel’s Conclusions
He concluded that factors are passed from one generation to the next.

5. Genes and Alleles Genes
Sequence of DNA that codes for a protein and determines a trait.
Alleles
Alternate forms of genes. One comes from your mom and one from your dad.

6. Dominant and Recessive alleles
Dominant alleles – represented by upper-case letters (B)
trait will always appear, only one dominant allele needed. (BB or Bb)
Recessive alleles – represented by lower case letters(b)
trait will not appear UNLESS both recessive alleles are present (bb).

7. Recessive traits show up about 1/4th of the time.
Because there is only a 25% chance that two recessive alleles will be paired together.

8. The Principle of Dominance
Paternal
Maternal
eye color locus
B = brown eyes
b = blue eyes
The Principle of Dominance
Some alleles are dominant and others are recessive. Recessive alleles are not expressed in the organism, but may be passed on to future generations.

9. Types of Allele pairing
Homozygous (purebred)
both alleles are the same
(BB – Brown eyes)
(bb – blue eyes)
Heterozygous (hybrid)
two different alleles
(Bb – Brown eyes)

10. Phenotype Genotype Arrangement of genes that produces the phenotype
Example:
1. BB, Bb
2. bb
Outward appearance
Physical characteristics
Examples:
1.Brown eyes 2.blue eyes

11. Punnett Square
A Punnett square is used to show the possible combinations of gametes and allow us to determine the probability of an allele combination.

12. Monohybrid Cross
Example: Cross between two heterozygotes brown eyes (Bb)
BB = brown eyes
Bb = brown eyes
bb = blue eyes B b
Bb x Bb
male
gametes
female gametes BB Bb bb Bb

13. Monohybrid Cross B b Bb x Bb BB Bb bb
BB= homozygous dominant; 1 of 4 = 25%
Bb= heterozygous dominant; 2 of 4 = 50%
bb= homozygous recessive; 1 of 4 = 25%
Chances of Brown Eyes: 3 of 4 = 75%
Chances of Blue Eyes: 1 of 4 = 25% B b
Bb x Bb BB Bb bb

14. Dihybrid Cross: RrYy x RrYy
CROSSES WITH TWO DIFFERENT TRAITS
Here’s your game plan:
FIRST: FOIL the alleles just like you do for polynomials in math class
(Rr) (Yy) x (Rr) (Yy)
First: RY RY
Inner: rY rY
Outer: Ry Ry
Last: ry ry

15. Dihybrid Cross: RrYy x RrYy
SECOND: take your results from your FOILing and place them on the sides of your Punnett square! Add like letters to like letters in the boxes. RY Ry rY ry RY Ry rY ry
RRYY

16. Dihybrid Cross RY Ry rY ry RRYY RRYy RrYY RrYy RRyy Rryy rrYY rrYy
Smooth/Yellow: 9 of 16
Smooth/green: 3 of 16
wrinkled/Yellow: 3 of 16
wrinkled/green: 1 of 16
9:3:3:1 phenotypic ratio
RRYY
RRYy
RrYY
RrYy
RRyy
Rryy
rrYY
rrYy
rryy

17. Incomplete Dominance
One allele is not completely dominant over another and the traits combine, or blend W R RW RW RW RW

18. a. List the possible genotypes and phenotypes genotypes – phenotypes –
Incomplete Dominance
a. List the possible genotypes and phenotypes
genotypes –
phenotypes –
b. How many of the plants would have red flowers?
c. How many would have white flowers?
How many would have pink flowers? RW
Pink W R RW 0% 0%
100%

19. Codominance
Black cow + white cow = spotted cow

20. Blood Types: A, B, AB, O

21. Codominance i i IA IA i IA i IA IA i IA i Example:
Blood Type O (ii) X Blood Type A (IAIA )
Both alleles are expressed
Example: blood
1. type A = IAIA or IAi
2. type B = IBIB or IBi
3. type AB = IAIB
4. type O = ii i i IA
IA i
IA i IA
IA i
IA i

22. Codominance GENOTYPE IAIA = ______ of ______=____% = Type________
IAi = of = 100% = Type A blood
IBIB = ______ of ______=____% = Type________
IBi = ______ of ______=____% = Type________
IAIB = ______ of ______=____% = Type________
ii = ______ of ______=____% = Type________

23. Karyotype Analysis
To analyze chromosomes, we cut up and assemble photographs of chromosomes in pairs.
There are 44 autosomal chromosomes and 2 sex chromosomes in humans.