1. Intro to Genetics

2. Genetics Student Expectation: B 6.F
Predict possible outcomes of various genetic combinations such as monohybrid crosses, dihybrid crosses and non-Mendelian inheritance.
Readiness Standard

3. Gregor Mendel Austrian monk born 1822 Lived in a monastery
and taught high school
Experimented with pea plants by cross breeding plants with different characteristics and studying results.
Known as the father of Genetics

4. Mendel’s Principles
Law of Inheritance – Characteristics or traits are inherited by individual units known as “genes”.

5. Vocabulary
Gene – the sequence of DNA that codes for a protein and thus determines a trait.
Example – a gene
will determine plant
height in peas.

6. Mendel’s Principles
Law of Segregation - states that during the formation of reproductive cells (gametes), pairs of hereditary factors (genes) for a specific trait separate so that offspring receive one factor from each parent.

7. Vocabulary Allele – one of a number of different forms of a gene.
Example:
this flower
carries an
allele for white
and an allele for purple flowers

8. Mendel’s Principles Law of Independent Assortment - states
that chance deter-
mines which factor
for a particular trait
is inherited.

9. Mendel’s Principles
Law of Dominance – states that when 2 or more forms of a gene exist (alleles), some forms are dominant and others are recessive

10. Dominant/Recessive
Hitch Hikers Thumb Normal Thumb

11. Dominant/Recessive
Free Earlobes Attached Earlobes

12. Dominant/Recessive

13. Polydactyly is Dominant!!

14. Dominant/Recessive Other examples of dominant traits: Dimples
Tongue Rolling
Freckles
Curly hair (may be more than one gene)

15. Dominant/Recessive Shapes for Pea seeds R = round (Dominant)
r = wrinkled (recessive)
Genotype Phenotype
RR Round homozygous dominant
Rr Round heterozygous dominant
rr wrinkled homozygous recessive

16. Monohybrid Crosses

17. Monohybrid Crosses

18. Monohybrid Crosses Practice some monohybrid crosses BB x BB BB x Bb
What are the genotypic ratios?
What are the phenotypic ratios?

19. Dihybrid Crosses

20. Non Mendelian Genetics
Exceptions to Mendel’s Principles:
Not all genes show simple patterns of dominant and recessive alleles
The majority of genes have more than two alleles.
Many traits are controlled by more than one gene.

21. Non Mendelian Genetics
Incomplete Dominance - When one allele is not dominant over the other but the heterozygous offspring produce an intermediate (3rd) phenotype. Neither fully expressed.
Example:
Red (RR) x white (rr)
= Pink (Rr)

22. Non Mendelian Genetics
Co-dominance - Both alleles contribute to the phenotype. Both are expressed at the same time.
Example:
Brown BB x
White WW
= brown and white - BW

23. Non Mendelian Genetics
Multiple Alleles - More than 2 possible alleles exist – not “either/or”. Only 2 expressed at a
time.
Example:
Blood Type
iA, iB, iAiB, ii
Blood Type
Genotype
Can Receive
Blood From A
iAi = AO
iAiA = AA
A or O B
iBi = BO
iBiB = BB
B or O AB
iAiB
A, B,
AB, O O
ii = OO

24. Multiple Alleles – Blood Types

25. Non Mendelian Genetics
Polygenic Traits - Traits controlled by several genes often on multiple chromosomes.
Examples:
Skin Color
Eye Color

26. Polygenic Traits
Skin Color

27. Non Mendelian Genetics
Sex Linked Traits -
Genes that are carried
by the sex chromosomes.
Read More:

28. Journal Work
In your journal you will work the following punnett squares. This will be a graded assignment.
You must re-write or abbreviate the questions and you must show your work and circle or hi-lite your answers.

29. Journal Work Problem 1
Identify each of the following as: Homozygous dominant, homozygous recessive or heterozygous.
A. bb
B. Hybrid
C. TT
D. Gg
E. Purebred

30. Journal Work - Problem 2 Dominant/Recessive Monohybrid Cross
Draw a Punnett square and provide the genotypic and phenotypic information.
I = Not allergic to Iodine i – allergic to iodine
Ii x II Genotypic ratios
Phenotypic ratios
Ii x ii Genotypic ratios

31. Journal Work - Problem 3 Dominant/Recessive Monohybrid Cross
Two elephants are crossed and the resulting offspring have 50% large ears and 50% small ears.
E = large ears e = small ears
What are the genotypes of the parent?
SHOW YOUR PUNNETT SQUARE.

32. Journal Work - Problem 4 Dominant/Recessive Monohybrid Cross
A black rabbit is crossed with a white rabbit. 100% of the offspring are heterozygous for color.
B = black b = white
What are the genotypes of the parent?
What are the phenotype percents for the offspring?
SHOW YOUR PUNNETT SQUARE.

33. Journal Work - Problem 5 Dominant/Recessive Monohybrid Cross
Cross a homozygous fuzzy bear with a hairless bear.
F = fuzzy f – hairless
What are the F1 genotypic ratios?
What are the F1 phenotypic ratios?

34. Journal Work - Problem 6 Dominant/Recessive Monohybrid Cross
Cross a heterozygous purple-flowered plant with a plant that has white flowers.
P = purple p – white
What are the F1 genotypic ratios?
What are the F1 phenotypic ratios?

35. Journal Work – Problem 7 Dominant/Recessive Dihybrid Cross:
Y – yellow peas P – purple flowers T-tall plant
y – green peas p – white flowers t – short plant
Cross two heterozygous tall, heterozygous yellow pea plants.
What are the parent genotypes?
What are the F1 genotypic ratios?
What are the F1 phenotypic ratios?

36. Journal Work – Problem 8 Dominant/Recessive Dihybrid Cross:
Y – yellow peas P – purple flowers T-tall plant
y – green peas p – white flower t – short plant
Cross a short, purple flower plant that is homozygous for color with a short, purple flower plant that is heterozygous for color.
Whate are the parent genotypes?
What are the F1 genotypic ratios?
What are the F1 phenotypic ratios?

37. Journal Work – Problem 9 Dominant/Recessive Dihybrid Cross:
Y – yellow peas P – purple flowers T-tall plant
y – green peas p – white flower t – short plant
Cross a heterozygous purple flowered, green pea plant with a plant that has white flowers and is heterozygous for pea color.
What are the parent genotypes?
What are the F1 genotypic ratios?
What are the F1 phenotypic ratios?

38. Journal Work – Problem 10 Incomplete Dominance - Monohybrid Cross:
In snapdragons, red and white are both dominant. When they cross, they produce a pink flower.
R – red R’ – white
Cross a homozygous red and a homozygous white
snapdragon.
What are the parent genotypes?
What are the F1 genotypic ratios?
What are the F1 phenotypic ratios?

39. Journal Work – Problem 11 Co - Dominance - Monohybrid Cross:
In a certain type of chicken, black and white feather share dominance. When they cross they produce chickens with both black and white feathers.
B - black B’ - white
Cross a homozygous black and a homozygous white chicken.
Whate are the parent genotypes?
What are the F1 genotypic ratios?
What are the F1 phenotypic ratios?

40. Journal Work – Problem 12
Incomplete and Co - Dominance - Dihybrid Cross:
In Fuzzy Trolls, Blue and Purple hair are both dominant. A hybrid genotype produces blue and purple stripes. Yellow skin and Red skin are both dominant. A hybrid genotype produces orange skin.
B – Blue hair Y – yellow skin
B’ – Purple hair Y’ Red skin
A troll with purple hair and red skin reproduces with a troll with blue hair and orange skin.
What are the parent genotypes?
What are the F1 genotypic ratios?
What are the F1 phenotypic ratios?

41. Journal Work – Problem 13 Multiple Alleles Monohybrid Cross:
Blood Type: Cross a
heterozygous Type A
with a heterozygous Type B.
Whate are the parent genotypes?
What are the F1 genotypic ratios?
What are the F1 phenotypic ratios?
Blood Type
Genotype
Can Receive
Blood From A
iAi = AO
iAiA = AA
A or O B
iBi = BO
iBiB = BB
B or O AB
iAiB
A, B,
AB, O O
ii = OO

42. Journal Work – Problem 14 Sex Linked - Monohybrid Cross:
A female who is a carrier for baldness marries a man with normal hair patterns
H – Normal hair pattern h – bald
What are the parent genotypes?
What are the F1 genotypic ratios?
What are the F1 phenotypic ratios?