1. Gregor Mendel
- A monk who studied peas in his garden and developed our basic understanding of heredity.

2. Allele Alternate forms of a gene Most traits have 2 alleles
Ex. Mendel’s peas

3. Blue eye or brown eye allele

4. Heredity
The transmission of characteristics from parents to offspring

5. Trait
The visible character that shows
Ex. Yellow pea or green pea

6. Genes
A discrete unit of hereditary information located on a chromosome

7. Generations P1 Generation – The original parents
F1 Generation – The first offspring
(Children)
F2 Generation – The offspring from the F1 gen. (grandchildren)

8. Law of segregation
When gametes (sperm and egg) form, only one of the 2 possible genes for each trait will be in each gamete

9. Dominant vs. Recessive
Dominant – The trait that is stronger or masks the other trait
Recessive – The trait that is weaker or hidden

10.                                                   
Dominant gene
Black fur is dominant to white

11. If there are both a dominant and recessive traits together, only the dominant one appears

12. G g Genotype The genes an organism carries
Ex: Gg = green (G) and yellow (g) genes G g

13. Phenotype How the genes are expressed (what it looks like)
Ex: Gg has both green and yellow genes but the phenotype is green because green is dominant

14. G Homozygous Dominant Both Dominant Genes Present Genotype = GG
Phenotype = Green GG G G

15. g Gg G Heterozygous 1 Dominant gene, 1 recessive gene present
Genotype = Gg
Phenotype = Green g Gg G

16. gg g g Homozygous Recessive Both recessive Genes Present Genotype = gg
Phenotype = Yellow gg g g

17. Monohybrid cross
Look at one single character

18. If we know the alleles of the parents, we can make predictions about the genetic traits of the offspring using A PUNNETT SQUARE!
Draw a Punnett square
Label 1 side with the genotype of one parent.
Label the other side with the genotype of the other parent.
Do the cross
Describe genotypes including the possible percentages for the offspring
Describe the phenotypes including the possible percentages for the offspring

19. Punnett Square Practice
1. Curly hair (H) is dominant to straight hair (h). Draw a punnett square crossing a heterozygous male (Hh) with a heterozygous female (Hh). Name all possible gentoypes and phenotypes and the percentages. H H
H h h h
Genotypes:
HH:
Hh:
hh:
Phenotypes:
Curly: Straight:
H h H H h h

20. Punnett Square Practice
2. Dimples (D) are dominant to not having dimples (d). Draw a punnett square crossing a homozygous dominant female (DD) with a homozygous recessive male (dd). Name all possible genotypes and phenotypes and the percentages. d d
d d d d
Genotypes:
DD:
Dd:
dd:
Phenotypes:
Dimples:
No Dimples:
D D D D D D

21. Punnett Square Practice
3. Unattached earlobes (E) are dominant to attached earlobes (e). Draw a punnett square crossing a homozygous recessive female with a heterozygous male. Name all possible genotypes and phenotypes and percentages.
e e
Genotypes:
EE:
Ee:
ee:
Phenotypes:
Attached: Unattached:
E e
Ee Ee
ee ee

22. Punnett Square Practice
4. Having freckles (F) is dominant to not having freckles (f). Draw a Punnett square crossing a heterozygous female with a homozygous dominant male. Name all possible genotypes and phenotypes and percentages.
F f
Genotypes:
FF: 50%
Ff: 50%
PhenotypesFreckles: 100%
F F
FF Ff

23. Punnett Square Practice
i i
5. Immunity to poison ivy is dominant to being susceptible to getting poison ivy. Draw a punnett square crossing a homozygous recessive female with a homozygous dominant male. Name all possible genotypes and phenotypes and percentages.
Genotypes:
Ii: 100%
PhenotypesImmunity: 100%
I I
Ii Ii

24. Punnett Square Practice
6. A widow’s peak is dominant to a normal hairline. Draw a punnett square crossing a heterozygous female with a heterozygous male. Name all possible genotypes and phenotypes and percentages.
W w
Genotypes:
WW: 25%
Ww: 50%
ww: 25%
PhenotypesImmunity:
Widows peak: 75%
Normal: 25%
W w
WW Ww
Ww ww

25. Cases in Genetics with Filbert the Frog and Friends

26. Dihybrid Punnett Squares
S: smooth
s: rough
Y: yellow
y: green
Dihybrid Punnett Squares
Genotypes: Phenotypes:
SSYY: 1/16
SSYy: 2/16
SSyy: 1/16
SsYY: 2/16
SsYy: 4/16
Ssyy: 2/16
ssYY: 1/ 16
ssYy: 2/16
ssyy: 1/16
Smooth Yellow: 9/16
Rough Yellow: 3/16
Smooth green: 3/16
Rough green: 1/16

27. Now try to make one… Genotypes: Phenotypes: BBSS: 1/16 BBSs: 2/16
B = black fur
b = brown fur
S = short fur
s = long fur
Now try to make one…
Genotypes:
Phenotypes:
BBSS: 1/16
BBSs: 2/16
BBss: 1/16
BbSS: 2/16
BbSs: 4/16
Bbss: 2/16
bbSS: 1/16
bbSs: 2/16
bbss: 1/16
BBSS BBSs BbSS BbSs
BBSs BBss BbSs Bbss
BbSS BbSs bbSS bbSs
BbSs Bbss bbSs bbss
Black, Short: 9/16
Brown, Short: 3/16
Black, Long: 3/16
Brown, Long: : 1/16

28. Try this one: BBSs vs. bbSs
B = black fur
b = brown fur
S = short fur
s = long fur
Try this one: BBSs vs. bbSs
Genotypes:
Phenotypes:

29. BBSs vs. bbSs BS Bs bS bs

30. Try this one: BBSs vs. bbSs
B = black fur
b = brown fur
S = short fur
s = long fur
Try this one: BBSs vs. bbSs
Genotypes:
Phenotypes:
bS bs bS bs
BbSS: 4/16
BbSs: 8/16
Bbss: 4/16 BS Bs
BbSS BbSs BbSS BbSs
BbSs Bbss BbSs Bbss
BbSS BbSs BbSS BbSs
Black, Short: 12/16
Black, long: 4/16

31. Homework:
Complete a dihybrid punnett square using this cross: TtRR x TTrr.
Tall (T) is dominant to short (t) and Red (R) is dominant to pink (r).
Find the genotype and phenotype percentages.