1. Genetics
SPI.4.4 Determine the probability of a particular trait in an offspring based on the genotype of the parents and the particular mode of inheritance.
SPI.M.2 Predict the outcome of a cross between parents of known genotype.

2. Genetics
The study of heredity

3. Gregor Mendel Father of genetics Worked with pea plants
Studied various traits
Trait – genetically determined
characteristic or condition

4. Different forms of the same gene
Alleles
Different forms of the same gene
Example: Hair color

5. First Experiment P
(parental) F1
100% Purple

6. Second Experiment F1 F2
75% Purple and
25% White

7. Gregor Mendel Four major conclusions: Inheritance factors
Principle of Dominance
Law of Segregation
Law of Independent Assortment

8. Mendel’s Conclusion
Inheritance is determine by factors passed down by parents
*factors = genes

9. Mendel’s Conclusions 2. Some alleles are dominant to others Recessive
*Appears in absence of dominant allele
*Lower case letter
Dominant
*Always appears when present
*Capital letter

10. Purple (P) color is dominant to white (p) color
Genotype
Allele combination
Phenotype
Physical appearance
Trait = Flower Color
Purple (P) color is dominant to white (p) color
Genotype?
PP or Pp pp
Phenotype?
Purple
White

11. Homozygous
Same alleles
Heterozygous
Different alleles

12. Mendel’s Conclusions 3. Law of Segregation
A pair of alleles is separated in the formation of gametes
Meiosis

13. Mendel’s Conclusions
4. Law of Independent Assortment Alleles on non homologous chromosomes will be distributed randomly into gametes

14. Punnett Squares
Monohybrid
1 trait
Dihybrid
2 traits 14

15. Punnett Square A A Aa Aa a a Aa Aa Gamete Parent 2 (aa) Parent 1 (AA)
Offspring genotype a Aa Aa

16. Example Tt tt Tall is dominant to Short in pea plants Tall – T
Short – t
Cross a heterozygous tall plant with a short plant
Parent 1
Parent 2 Tt tt 16

17. Example Cross T t Tt t tt t Tt tt 17

18. Probability
Predict the chance of each phenotype’s occurrence
Think of each little square as a quarter
Think of each large square as a dollar 25 25
= 100 25 25 18

19. Example Cross T t t Tt tt
50%
50% t Tt tt 19

20. Monohybrid Cross Rules
100% of the offspring – dominant phenotype
At least 1 parent is homozygous dominant
100% of the offspring – recessive phenotype
Both parents are homozygous recessive
75% dom. pheno. & 25% rec. pheno.
Both parents are heterozygous
50% dom. Pheno. & 50% rec. pheno.
1 parent is heterozygous &
1 parent is homozygous recessive

21. Shows independent assortment
Dihybrid
Examines two traits
Shows independent assortment
Pea Plants
Round seeds (R) are dominant to wrinkled (r)
Yellow seeds (Y) are dominant to green (y)
How many traits are we looking at?
So how many alleles per parent?
So how many alleles per gamete? 2 4 2 21

22. RrYy Finding Gametes? FOIL F – first O – outer I – inner F – RY
L – last
RrYy
F – RY
O – Ry
I – rY
L – ry 22

23. Dihybrid Cross Reveal from left to right & top to bottom
Video link in picture to Amoeba Sisters Dihybrid Crosses 23

24. Lethal Inheritance Inherited allele may cause death Prolonged
Huntington’s disease
Immediate
Humans – Tay Sacs
Plants - Albino 24

25. Autosomal Versus Sex Chromosomes
Autosomes
All chromosomes
except X or Y
Sex Chromosomes
Female XX
Male XY 25

26. Inheritance of Sex Chromsomes
Mother always
give s an X to the
offspring
Father gives an
X or Y to the
offspring
Most sex-linked traits are on the X chromosome 26

27. Males are more likely to show
Sex Linked Traits
Males are more likely to show
Males only have one X
Examples:
Male Pattern Baldness
Colorblindness
Hemophilia 27

29. Sex Linked Punnetts
Gender must be included for sex linked punnetts. Hemophilia is a sex linked recessive trait. Cross a normal male with a female who is a carrier for hemophilia. 29

30. Incomplete Dominance occurs when a heterozygous genotype results in an intermediate trait
Trait 1 – 2 capital letters
Example: red flowers = RR
Trait 2 – 2 capital letters
Example: white flowers = WW
Heterozygous = Mix
Example – Pink RW 30

31. Incomplete Domiance White Seahorse Black Seahorse Gray Seahorse WW BBBW 31

32. Incomplete Dominance What color are the parents?
Gray
What color is the top left seahorse?
Black
What color is the bottom right seahorse?
White
What color are the BW? 32

33. Codominance Share dominance CBCW CBCB CWCW
Use a capital letter for trait with a different exponent letter to represent each allele
CBCW
CBCB
CWCW 33

34. Codominance Punnett Cross a speckled chicken with a black chicken.CB CW
CBCB
CBCW CB CB 34

35. Traits having >2 allele options
Multiple Alleles
Traits having >2 allele options
Example: Rabbit Coat Color

36. Multiple Alleles & Codominance
Human example: blood types
Blood types are A, B, AB, O.
A & B are dominant alleles (IA or IB) and O is recessive (i).

37. Codominance Example: Blood types A B AB O Genotype- IAIA or IAi
Fights B or AB
Genotype- IBIB
Or IBi
Fights A or AB
Genotype- IAIB
Fights None
Universal
Recipient
Genotype- ii
Fights all but O
Universal
Donor 37

38. How common is your blood type?
46.1%
38.8%
11.1%
3.9%

39. Blood Type Punnett
Cross a man that is heterozygous for B blood with a woman who has AB blood. 39

40. Blood types

41. Polygenic Traits Traits produced by the interaction of several genes
Example: Human Skin Color
3-6 genes
Amount of melanin
Incomplete dominance

42. Eye Color Amount of melanin in iris Chromos. 15 – Brown from Blue
Chromos. 19 – green & blue
Iris
Anterior – front
Posterior – back

43. Environment Affects Nutrition Exercise Heart disease Epigenome
Epigenome video
Review video AS in picture

44. Types of Inheritance Inheritance Letters Heterozygous Other Complete
# of Dominant Alleles
Other
Complete
A-dominant
a- recessive
Dominant covers recessive 1
Default
Incomplete
A – trait 1
B- trait 2
A & B phenotypes will mix
Remember to blend the 2
CoDominance
Ay – Dom 1
Az – Dom 2
a-recessive
Either both show up or if Ay a – dom. 2
Hetero can be both or the dom.
Sex Linked
XaXa
XaY
Only female can be hetero
Males either have trait or not 44