1. Genetics Is the science of heredity.
Heredity is the transmission of genetic or physical traits from parent to offspring.

3. Gregor Mendel Austrian Monk – born 1822
Considered the “Father of Heredity”
He conducted plant breeding experiments in their monastery garden using peas.
Developed the Laws of Inheritance.

4. Particulate Inheritance
Mendelian Genetics
4/21/2018
Particulate Inheritance
Mendel stated that physical traits are inherited as “particles”
Mendel did not know that the “particles” were actually Chromosomes & DNA

5. What would Gregor Mendel have said if he knew he’d been named the “Father of Genetics”?
“WHOO-PEA!”

6. Do chromosome numbers increase as species become more advanced?
Common Name
Diploid Number
Monkey 42
Dog 78
Human 46
Mouse 40
Frog 26
Flatworm 16
Corn 20
Yeast 32
Potato 48
Green Algae
Fruit Fly 8

7. Sex Determination
Female can contribute only an X chromosome towards the sex of their offspring.
Male can contribute an X or a Y chromosome toward the sex of their offspring.
Absence of a Y chromosome results in a the embryo developing into a female.
Presence of a Y chromosome results in the embryo developing into a male.
So, what is the genotype of a FEMALE? MALE?

8. Genes Some traits are inherited directly from one set of genes.
Some traits are inherited through several sets of genes.

9. Terms to know
Homozygous- contains 2 identical alleles for the same trait, AA, BB, cc (Purebred)
Heterozygous- contains 2 different alleles for the same trait, Aa, bB, Cc (Hybrid)
Phenotype- Outward appearance of a trait, coat color, polled, horned. description
Genotype- Genetic makeup for gene, AA, Aa, aa. letters
Allele- Specific gene for specific trait.
F-one = First cross offspring mating.
F-two = Second cross offspring

11. Let’s practice . . . Are these homozygous or heterozygous? EE AA Cc dd
t t Bb LL Pp jj

12. What are dominant genes?
The gene that expresses itself
These hide the recessive gene if there is complete dominance.
Some examples of dominant traits in humans are:
Broad lips (BB or Bb)
Second toe longer (TT or Tt)
Brown eyes (BB or Bb)
Freckles (FF or Ff)
Rolling tongue (RR or Rr)
Detached earlobe (EE or Ee)

13. What are Recessive Genes?
The gene that is overshadowed by a dominant gene – hidden by dominant
Recessive genes can only express themselves when there are two
Some examples of dominant traits in humans are:
Thin lips (bb)
Color blindness (cc)
Near sightedness (nn)
No dimples (dd)
Attached earlobes (ee)

14. Let’s practice . . .
Are these homozygous or heterozygous and dominant or recessive? EE AA Cc dd
t t Bb LL Pp jj

15. More Terms to know – you will need to add these to your notes
Codominance Alleles are equally expressed, there is no dominance. Results in BOTH phenotypes being visible.
Incomplete Dominance Neither allele is dominant, heterozygotes show a BLEND, there is no dominance.
Gene A segment of DNA that codes for a trait.
Heredity Transmission of genes from parent to offspring.

16. Vocabulary Practice
Pair up with your neighbor and match the term with the correct definition.

17. Mendel’s Laws Law of Dominance
In a cross of parents that are pure for contrasting traits only one form of the trait will appear in the next generation. (If one parent is HH and the other is hh, all offspring will show dominant trait)
All the offspring will be heterozygous and express only the dominant trait.

18. Mendel’s Laws Law of Segregation
During meiosis, the formation of gametes (eggs or sperm), the two alleles responsible for a trait separate from each other.
Alleles for a trait are then "recombined" at fertilization, producing the genotype for the traits of the offspring.

19. Mendel’s Laws Law of Independent Assortment
Alleles for different traits are distributed to sex cells (& offspring) independently of one another.
Offspring may look different from parents and each other!
This law can be illustrated using dihybrid crosses.
Red hair and freckles does not travel together!

20. Punnet Square Angus- Black coat color is dominant over red.
Cross a heterozygous with a homozygous recessive cow.
Make a KEY:
BB = Homozygous Dominant and black
Bb = Heterozygous and black
bb = Homozygous recessive and red
Write the Parent Cross _________X__________

21. Punnet Square

22. Punnet Square

23. Results 2 heterozygous = Bb 2 Homozygous Recessive = bb
50% Black, 50% Red
Genotypic ratio = 2:2 = 1:1
Phenotypic ratio = 2 Black: 2 Red = 1:1

24. Take out a sheet of paper
Title – “Types of Monohybrid Problems”
Dominance
Incomplete Dominance
Co-Dominance
Sex Linked
Multiple Alleles

25. 1. Dominance
Brown bunnies are dominant over white bunnies. Cross two heterozygous brown bunnies. What is the chance there will be a white bunny born?
Make a key: Parent Cross:
BB – ________X________
Bb –
bb -

26. 1. Dominance
Brown bunnies are dominant over white bunnies. Cross two heterozygous brown bunnies. What is the chance there will be a white bunny born?
Make a key: Parent Cross:
BB – Brown __Bb__ X __Bb__
Bb - Brown
bb – white Work the punnet square . . .

27. 1. Dominance B b BB B Bb b Bb bb Make a key: Parent Cross:
BB – Brown __Bb__ X __Bb__
Bb - Brown
bb – white Work the punnet square . . .
B b B b BB Bb Bb bb

28. 1. Dominance B b B b BB Bb Bb bb Make a key: Parent Cross:
BB – Brown __Bb__ X __Bb__
Bb - Brown
bb – white Work the punnet square . . .
Chance of a
white bunny?
1 in 4 or
25% chance
B b B b BB Bb Bb bb

29. 2. Incomplete Dominance
Red roses and white roses result in pink roses. Cross a red rose with a pink rose. What is the genotypic ratio and phenotypic ratio of the offspring?
Make a key: RR RW WW

30. 2. Incomplete Dominance
Red roses and white roses result in pink roses. Cross a red rose with a pink rose. What is the genotypic ratio and phenotypic ratio of the offspring?
Make a key: What is the
RR – red Parent Cross?
RW – pink ________X________
WW - white

31. 2. Incomplete Dominance
Red roses and white roses result in pink roses. Cross a red rose with a pink rose. What is the genotypic ratio and phenotypic ratio of the offspring?
Make a key: What is the
RR – red Parent Cross?
RW – pink __RR__X__RW__
WW – white
Work a Punnett Square . . .

32. 2. Incomplete Dominance R R R W RR – red Parent Cross?
Make a key: What is the
RR – red Parent Cross?
RW – pink __RR__X__RW__
WW – white
Work a Punnett Square . . .
R R R W

33. RR RW 2. Incomplete Dominance R R R W RR – red Parent Cross?
Make a key: What is the
RR – red Parent Cross?
RW – pink __RR__X__RW__
WW – white
Work a Punnett Square . . .
R R R W RR RW
Genotypic ratio:
Phenotypic ratio:

34. 3. Co-Dominance Make a key: BB - Red BW – Red and White spots
WW - White

35. 3. Co-Dominance
Black chupacabras and white chupacabras make black and white stripped chupacabras. Cross a black chup and a white chup. What is the genotypic ratio what will the offspring look like?
Make a key:
BB -
BW -
WW -

36. 3. Co-Dominance
Black chupacabras and white chupacabras make black and white stripped chupacabras. Cross a black chup and a white chup. What is the genotypic ratio what will the offspring look like?
Make a key: What is the
BB – black Parent Cross?
BW – stripped _____X_____
WW - white

37. 3. Co-Dominance
Black chupacabras and white chupacabras make black and white stripped chupacabras. Cross a black chup and a white chup. What is the genotypic ratio what will the offspring look like?
Make a key: What is the
BB – black Parent Cross?
BW – stripped _BB_X_WW_
WW - white
Work a Punnett Square . . .

38. 3. Co-Dominance B B W Make a key: What is the BB – black Parent Cross?
BW – striped blk/white _BB_X_WW_
WW - white
Work a Punnett Square . . .
B B W

39. BW BW BW BW 3. Co-Dominance B B W Make a key: What is the
BB – black Parent Cross?
BW – stripped _BB_X_WW_
WW - white
Work a Punnett Square . . .
B B W BW
Genotypic ratio:
Phenotypes: BW BW BW

40. 4. Sex-Linked
Color blindness is a sex linked recessive trait carried on the X chromosome. Cross a colorblind male with a female carrier. What is the chance of a colorblind child?
Make a key: Parent Cross:
______X______

41. 4. Sex-Linked
Color blindness is a sex linked recessive trait carried on the X chromosome. Cross a colorblind male with a female carrier.
Make a key: Parent Cross:
XCXC – Normal vision XcY X XCXc
XCXc – Normal but carrier
XcXc – Colorblind
XCY – Normal vision
XcY – Colorblind Work a punnet square

42. 4. Sex-Linked Xc Y Xc XC Make a key: Parent Cross:
XCXC – Normal vision XcY X XCXc
XCXc – Normal but carrier
XcXc – Colorblind
XCY – Normal vision
XcY – Colorblind Work a punnet square
Chance of colorblind
child? 2 out of 4
50% chance
Xc Y XC Xc
XCXc
XCY
XcXc
XcY

43. 5. Multiple Allele Blood Types have 3 alleles! AA, AO = Type A blood
A, B and O (O is recessive to A and B)
AA, AO = Type A blood
BB, BO = Type B blood
AB = Type AB blood
OO = Type O blood
SIX possible combinations for parents
Cross a Type O mom with a Type AB dad.
What are the possible phenotypes of the offspring?

44. AO BO AO BO 5. Multiple Allele A B O
Cross a Type O mom with a Type AB dad. What are the phenotypes of the offspring?
Parent Cross: OO x AB
Offspring phenotypes:
Type A and Type B
50% chance of either
A B O AO BO AO BO

45. Dihybrid Cross RrYy x RrYy
Mendelian Genetics
4/21/2018
Dihybrid Cross
What about crossing more than one trait? Let’s look at traits for Seed shape & color
Alleles:
R round
r wrinkled
Y yellow
y green
RrYy x RrYy
RY Ry rY ry
RY Ry rY ry
Use “FOIL” to find all possible gamete combinations

46. Mendelian Genetics
4/21/2018
Dihybrid Cross RY Ry rY ry RY Ry rY ry

47. Dihybrid Cross RY Ry rY ry Round/Yellow: 9 Round/green: 3
Mendelian Genetics
4/21/2018
Dihybrid Cross RY Ry rY ry
Round/Yellow: 9
Round/green: 3
wrinkled/Yellow: 3
wrinkled/green: 1
9:3:3:1 phenotypic ratio
RRYY
RRYy
RrYY
RrYy
RRyy
Rryy
rrYY
rrYy
rryy

48. Are there any shortcuts?
YES!!!
Cross AaBB with AaBb
Cross AAbb with aaBB
Cross AABb with AABB
Heterozygous to Heterozygous
(AaBb x AaBb)
is ALWAYS 9:3:3:1 phenotypic ratio.