1. Patterns of Heredity - Genetics -
Sections: 10.2, 11.1, & 11.2

2. Genetics = the study of heredity by which traits are passed from parents to offspring
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3. Do Now- True for False if false, correct the statement.
1. Certain acquired characteristics, such as mechanical or mathematical skill may be inherited.
2. Certain thoughts or experiences of a mother mark or alter the hereditary makeup of an unborn child.
3. Color blindness is more common in males than in females.
4. A person may transmit characteristics to offspring which he/she does not show.
5. Certain inherited traits may be altered by the stars, planets or moon early in development.
6. The total number of male births exceeds female births each year.

4. The Problem….

5. Another Example…

6. Heredity = The passing of genes/traits from parents to offspring
Many of your traits, including eye color, shape of your eyes, texture of your hair, height, weight, resemble those of your parents!

7. How are traits passed on?
….. CHROMOSOMES!

8. Let’s review the structure of a chromosome...
A pair of chromosomes are considered homologous (homo meaning same)
Homologous chromosomes have the same size, structure, and genetic information (genes).

9. It consists of a specific nucleotide sequence
What is a gene?
A unit of heredity that occupies a specific location on a chromosome and codes for a particular protein.
It consists of a specific nucleotide sequence

10. Alleles
Alternative forms of a gene that occupy corresponding positions on homologous chromosomes.

11. The History of Gregor Mendel
Austrian Monk – Czech
Bred different varieties of garden pea.
First to develop rules that accurately predict patterns of heredity.
Determined specific units of inheritance = genes and alleles
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12. Page 278

14. Mendel’s 3 Principles of Inheritance (Laws)
1. The Law of Dominance: An organism with alternate forms of a gene will express the form that is dominant.
If an organism has at least 1 dominant allele, that trait will be expressed! Dd
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15. 2. The Law of Segregation: The two alleles for a trait segregate into gametes during meiosis

16. 3. Law of independent assortment – alleles of different genes separate independently of one another during gamete formation.

17. phenotype: the physical appearance of a trait
Phenotype vs. Genotype
Genotype: The set of alleles that an individual has (not always obvious)
phenotype: the physical appearance of a trait

18. Heterozygous vs. Homozygous
Different alleles present
Ex: Bb
Two of the same alleles
Ex: BB or bb
Homozygous recessive or homozygous dominant

19. Recessive vs. Dominant
Recessive: The trait not expressed when the dominant form of the trait is present
Dominant: The expressed form of the trait when present (even if it is just 1 allele)

20. Example: In dogs, black fur is dominant over white fur color
Example: In dogs, black fur is dominant over white fur color. B = black b = white
BB or Bb bb

21. DO NOW If Chris Hemsworth’s phenotype is blonde hair…
(H=brown, h=blonde)
1. What his genotype?
2. Would his alleles be homozygous dominant, homozygous recessive, or heterozygous?
Beyonce’s phenotype is brown hair.
1. What is her genotype?
2. Would her alleles be homozygous dominant, homozygous recessive, or heterozygous
What are the chances their offspring would have brown hair? Create a punnett square?

22. Punnett Square
A diagram that predicts the outcome of a genetic cross by considering all possible combinations of gametes in the cross.
Crossing only 1 trait is called a monohybrid cross.
Crossing 2 traits is called a dihybrid cross.
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23. Phenotypic Ratio and %:
Genotypic Ratio :

24. Probability
Probability calculations can predict the results of genetic crosses. It is the likelihood that a specific event will occur.
= number of one kind of possible outcome
Total number of all possible outcomes
Example: If you flip a coin, you will have 1 outcome, but two possible outcomes. Your answer would be ½.
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25. Probability in a Punnett Square
1. What is the phenotypic ratio?
2. What is phenotypic %?

26. How do you write a ratio?
When flipping a coin and it lands on tails ➔ ½ or 1:2
Genotypic ratio: What is genetically written.
Phenotypic ratio: what physical traits you would see

27. Phenotypic Ratio and %:
Genotypic Ratio :

31. Do Now
Daffy Duck is heterozygous for black feathers. Daisy Duck is homozygous for yellow feathers. Set up a punnett square and determine probabilities of their potential offspring. (Both genotype and phenotype ratios!)
B = Black b = yellow

32. Setting up Dihybrid Crosses
1. Determine parent genotypes
2. Determine alleles to be passed down
3. Set up punnet square
4. Determine outcome
Genotype Ratio
Phenotype Ratio

33. Dihybrid Crosses Looking at two different traits
Ex. Hair color and eye color
B=brown eyes
b=blue eyes
R=Brown hair
r=blonde hair
Mother is heterozygous for both traits
Father is heterozygous for eye color and homozygous dominant for hair color

35. Do Now
Aladdin and Jasmine want to have children. Jasmine is homozygous dominant for black hair and black eyes.
Aladdin is homozygous recessive for brown eyes and brown hair.
B=black hair b=brown hair
E=black eyes e=brown eyes

36. Do Now B=black hair b=brown hair E=black eyes e=brown eyes
Jasmine’s daughter falls in love with a man who is also heterozygous for hair and eye color. Determine possible genotype and phenotype ratios.

37. Phenotypic Ratio and %:
Genotypic Ratio :

42. Create your family tree!
Do Now
Create your family tree!

43. Test Cross
In a test cross, an individual whose phenotype is dominant, but whose genotype is not known, is crossed with a homozygous recessive individual.
Ex: Brown eyes are brown, but can be BB or Bb.
To find out if the person with brown eyes is homozygous or heterozygous, you cross it with a recessive person's genotype and the outcome will tell you depending on the ratio
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44. Spongebob squarepants doesn’t know whether or not he is Homozygous Dominant or Heterozygous for his yellow color. The recessive trait is a white sponge. Let’s say that we perform a “test cross” on spongebob (spongebob + a white female sponge) and all of the baby sponges are yellow. What would spongebob’s genotype be?

45. Pedigree -
a family history that shows how a trait is inherited over several generations.
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301

46. Symbols for Pedigree

47. Using Pedigrees Inferring Genotypes
Knowing physical traits can determine what genes an individual is most likely to have.
Predicting Disorders
Scientists use pedigree analysis to study:
inheritance patterns
determine phenotypes
genotypes.

48. You can see how a genetic disorder runs in a family.
Carriers are individuals who are heterozygous for an inherited disorder but do not show symptoms.
Carriers can pass the allele for the disorder to their offspring

52. DO NOW
Fill in possible genotypes. Use the letter B!

54. Types of Inheritance
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56. Incomplete dominance – a trait that is intermediate between two parents

58. DO NOW
2 PINK four o’clock flowers are crossed. The offspring are red, pink, and white.
1. Draw the Punnett square.
2. Determine the phenotype ratio.
3. What type of inheritance is this?

59. Codominance
Neither trait is dominant instead, both traits are shown (No Blending)
Ex) Roan Cows
Red + White = RED AND WHITE

63. Codominance – two dominant alleles are expressed at the same time.

65. Determine Blood Type
Determine the possible offspring of the following crosses below →
1. AB and O
2. AA and BO
3. AB and AB

66. Multiple alleles – genes with 3 or more alleles

67. Polygenic Traits – several genes influence a trait
A wide range of variability! Genes can be located on different chromosomes

68. Sex-Linked Traits Red-green colorblindness Male Pattern Baldness
Hemophilia
Compare:
Male : XhY XHY Female: XHXH XHXh XhXh

69. Autosomal vs. Sex-Linked

70. What do you see?

72. Traits can be influenced by the environment!
Hydrangea Flowers:
When in acidic soil, they bloom blue flowers
When in basic soil, they will bloom pink flowers
Arctic Fox – Enzymes will make pigments during a certain time of the year.

73. Genetic Disorders Sickle Cell Anemia Cystic Fibrosis (CF) Hemophilia
Tay- Sachs Disease
Huntington’s Disease (HD)
Hypercholesterolemia
In Groups, you will research a specific disease and present it to the class.
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