1. Genetics and Inheritance

2. What makes you, you?
DNA
DNA is a system of codes that controls every aspect of your life (how you look, how you act, etc.)
DNA is like the instruction manual to keep you working.

3. DNA  gene Gene: one section of DNA that controls one specific trait.
(Examples: Hairline gene, earlobe gene, etc.)

4. DNA  gene  chromosome

5. How are these traits passed from one generation to the next?
Every living things inherits traits, or characteristics, from its parents.
How are these traits passed from one generation to the next?
The answer lies in the study of genetics.

6. Essential Question: Mendelian Genetics "How can two brown fur rabbits
have a
white fur baby?"

7. Genetics Definition = The branch of biology that studies heredity.
(Heredity = biological inheritance)

8. ~Austrian monk ~Experimented with pea plants
Gregor Mendel
“Father of Genetics”
Gregor Mendel   
~Austrian monk ~Experimented with pea plants

9. Mendel observed seven traits that are easily recognized and apparently only occur in one of two forms:

10. Mendel knew an important fact of his pea plants: the flowers have both male and female reproductive parts.

11. Pollination
Pea plants contain both male and female parts, so they can produce seeds by SELF-POLLINATION
Fertilization of a plant’s egg cells by the pollen of another plant: CROSS-POLLINATION

14. Terminology:
1. Gene: a section of DNA that controls a specific trait
Allele: alternative form of a GENE (one version of the gene)
Trait: a characteristic of a species determined by specific genes (observable)

15. Dominant gene: the presence of this type of gene will mask/hide the other gene
Recessive gene: this gene is hidden by the other gene unless there are two copies of the recessive form.

16. Video from: http://ed. ted

17. By breeding many plants over and over, he found that "statistically"
Results
By breeding many plants
over and over,
he found that "statistically"
certain traits appeared
with a certain probability

18. Mendel’s Results and Conclusions:
Biological characteristics are determined by genes.
(Genes are passed from parents to their offspring.)

19. Mendel’s Results and Conclusions:
Some forms (alleles) of a gene may be dominant, others may be recessive.

20. Mendel Devised 2 Laws
1. Law of Segregation: Two copies of each gene are segregated/separated from each other when gametes are formed.
Remember: one copy from each parent

21. Mendel Devised 2 Laws
2. Law of Independent Assortment: The alleles for different genes segregate independently of one another.
This is usually the case

22. When put together…

23. Terminology continued:
6. Hybrid: offspring of parents with different traits
7. Homozygous: both pairs of genes for a specific trait are the same
8. Heterozygous: both pairs of genes are different

24. Terminology continued
9. Genotype: the genetic makeup of an organism
(ie. AA, Aa, aa)
10. Phenotype: the physical appearance of an organism
(ie. Hair color, eye color, etc.)

25. Monohybrid Crosses A cross between individuals that involves ONE pair of contrasting traits

26. Punnett Squares!!! tool used to determine the probability of offspring of a cross between 2 parents

27. Punnett Squares B b MonoHybrid Cross = DOMINANT (capital letter)
Can be used to predict & compare the genetic variations that will result from a cross
= DOMINANT
(capital letter)
= DOMINANT B
MonoHybrid Cross
= recessive
(lower case)
= recessive b

28. Punnett Squares
Squares
Punnett
Can be used to predict & compare the genetic variations that will result from a cross
= DOMINANT
= DOMINANT
(capital letter)
HOMOzygous = organisms that have 2 IDENTICAL alleles for the same trait B
= recessive
(lower case)
= recessive
HETEROzygous = organisms that have 2 DIFFERENT alleles for the same trait b

29. The likelihood that a particular event will occur
9/13/2018 3:06 AM
Probability
The likelihood that a particular event will occur
Squares
Punnett
Segregation
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30. Test Cross
A mating between an individual with an unknown genotype and an individual that is HOMOZYGOS RECESSIVE.
Look at offspring to determine parent genotype
To determine the GENOTYPE of an organism expressing the dominant phenotype.
Example: Labrador Retriever
B- back fur
b= chocolate brown fur
Black lab X chocolate lab
B___ X bb

31. Test Cross Example
In humans, long eyelashes (E) is dominant to short eyelashes (e).
A man with long eyelashes marries a woman with short eyelashes and they have three children, two of whom have long eyelashes and one of whom has short eyelashes.
Draw the Punnett squares that illustrates this marriage. What is the man’s genotype? What are the genotypes of the children?

32. Dihybrid Crosses A cross between individuals that involves TWO distinct genes

34. Patterns of Inheritance and Non-Mendelian Genetics

35. One allele can completely hide the other (Mendellian trait)
1. Complete Dominance
One allele can completely hide the other (Mendellian trait)

36. Flower Color in Snapdragon
2. Incomplete Dominance
=both alleles
influence
the phenotype
Flower Color in Snapdragon
(blending)

37. Incomplete dominance in humans
hypercholesterolemia
Incomplete dominance in humans

38. Incomplete Dominance
Snapdragons
Red (RR)
White (WW)
Pink (RW)

39. Punnett Squares with Incomplete Dominance
Cross a White Snapdragon with a Red Snapdragon
a. Determine the genotypes of the parents and the gametes they will contribute to their offspring.
Phenotypes
Genotypes
Gametes
White WW W
Red RR R
b. Set up your punnett square . . .

40. Punnett Squares with Incomplete Dominance
Results
RR x WW R R
Genotypes
100% RW
Phenotypes
100% Pink W RW RW W RW RW

41. Punnett Squares with Incomplete Dominance
Cross Two Pink Snapdragons
a. Determine the genotypes of the parents and the gametes they will contribute to their offspring.
Phenotypes
Genotypes
Gametes
Pink RW
R, W
b. Set up your punnett square . . .

42. Punnett Squares with Incomplete Dominance
Cross Two Pink Snapdragons
Results
Genotypes
25% RR
50% RW
25% WW
RW x RW R W R RR RW
Phenotypes
25% Red
50% Pink
25% white W RW WW

43. (both traits are seen—spotting)
3. Codominance
Neither alleles totally masks the other
(both traits are seen—spotting)
RR = red hair
rr = white hair
Rr = roan (red AND white hairs present)

44. Codominance and multiple alleles
Most common blood type
Codominance and multiple alleles

45. Codominance
Cattle coat color
Red (RR)
White (WW)
Roan (RW)

46. Punnett Squares with Codominance
Cross a white heifer with a red bull
a. Determine the genotypes of the parents and the gametes they will contribute to their offspring.
Phenotypes
Genotypes
Gametes
white WW W
red RR R
b. Set up your punnett square . . .

47. Punnett Squares with Codominance
Cross a white heifer with a red bull
WW x RR
Results W
Genotype
100% WR
Phenotype
100% Roan R WR

48. Punnett Squares with Codominance
Cross two Roans
a. Determine the genotypes of the parents and the gametes they wll contribute to their offspring.
Phenotypes
Genotypes
Gametes
Roan RW
R, W
b. Set up your punnett square . . .

49. Punnett Squares with Codominance
Results
Cross two Roans
Genotype
25% WW
50% WR
25% RR
WR x WR W R W WW WR
Phenotype
25% White
50% Roan
25% Red WR RR R

50. Punnett Squares with Multiple Alleles
Human Blood Types
Alleles: IA, IB, IO
Type A: IAIA or IAIO
Type B: IBIB or IBIO
Type AB: IAIB
Type O: IOIO

51. Punnett Squares with multiple alleles
A woman who is homozygous for Type A has a child with a man who is heterozygous for type B.
a. Determine the genotypes of the parents and the gametes they will contribute to their offspring.
Phenotypes
Genotypes
Gametes
Mom
IAIA
IA, IA
Dad
IBIO
IB, IO
b. Set up your punnett square . . .

52. Punnett Squares with multiple alleles
Mom is homozygous Type A, Dad is heterozygous type B
IAIA x IBIO
Genotype
50% IAIB
50% IAIO
Phenotype
50% Type AB
50% Type A IA IA IB
IAIB
IAIB IO
IAIO
IAIO

53. Punnett Squares with multiple alleles
What would be the result of woman who is Type O with a man who is Type AB?
a. Determine the genotypes of the parents and the gametes they wll contribute to their offspring.
Phenotypes
Genotypes
Gametes
Mom
IOIO
IO, IO
Dad
IAIB
IA, IB
b. Set up your punnett square . . .

54. Punnett Squares with multiple alleles
Mom is homozygous Type A, Dad is heterozygous type B
IOIO x IAIB
Genotype
50% IAIO
50% IBIO
Phenotype
50% Type A
50% Type B IO IO IA
IAIO
IAIO IB
IBIO
IBIO

55. Punnett Squares with multiple alleles
Jack and Jill have their first child. Jack is heterozygous type B while Jill is heterozygous Type A. Can they have a child with type O blood?
a. Determine the genotypes of the parents and the gametes they wll contribute to their offspring.
Phenotypes
Genotypes
Gametes
Mom
IAIO
IA, IO
Dad
IBIO
IB, IO
b. Set up your punnett square . . .

56. Punnett Squares with multiple alleles
Mom is heterozygous Type B, Dad is heterozygous type A
Genotype 25% IAIB 25% IAIO 25% IBIO 25% IOIO Phenotype 25% Type A 25% Type B 25% Type AB 25% Type O
IBIO x IAIO IB IO IA
IAIB
IAIO IO
IBIO
IOIO

57. Blood Type Frequencies

58. One trait is controlled by multiple genes
4. Polygenetic
One trait is controlled by multiple genes
Examples:
Height,
skin color
Manifests as a wide range (gradient) of phenotypes.

59. Punnett Squares with polygenic traits
Even though eye color is controlled by at least three genes, we really understand how brown/blue/green colors work as controlled by two genes…
Eyecolor:
Gene 1: the green/blue eye color gene, located on chromosome 19.
green is dominant (G) , blue is recessive (g)
Gene 2: the central brown eye color gene, located on chromosome 15.
brown in dominant (B) , blue is recessive (b)

60. Punnett Squares with polygenic traits
Eyecolor:
Gene 1: green is dominant (G) , blue is recessive (g)
Gene 2: brown in dominant (B) , blue is recessive (b)
Brown eyecolor: B???
Green eyecolor: bbG?
Blue eyecolor: bbgg

61. Punnett Squares with polygenic traits
What would be the result of a cross between a blue-eyed person (recessive for both genes) and a brown-eyed person (heterozygous for both genes)
a. Determine the genotypes of the parents and the gametes they will contribute to their offspring.
Phenotypes
Genotypes
Gametes
Blue eyed
bbgg bg
Brown-eyed
BbGg
BG, Bg, bG, bg
b. Set up your punnett square . . .

62. Punnett Squares with polygenic traits
Results: 25% BbGg 25% Bbgg 25% bbGg 25% bbgg
bbgg X BbGg bg BG
BbGg Bg
Bbgg
Phenotypes:
50% brown
25% green
25% blue bG
bbGg bg
bbgg

63. Punnett Squares with polygenic traits
What is the result when a brown-eyed man (heterozygous for both genes) is crossed with a heterozygous green eyed woman?
a. Determine the genotypes of the parents and the gametes they will contribute to their offspring.
Phenotypes
Genotypes
Gametes
Green-eyed
bbGg
bG, bg
Brown-eyed
BbGg
BG, Bg, bG, bg
b. Set up your punnett square . . .

64. Punnett Squares with polygenic traits
BbGg X bbGg
Genotypes: Phenotypes: 1/8 BbGG 4/8 brown 2/8 BbGg 3/8 green 1/8 Bbgg 1/8 blue 1/8 bbGG 2/8 bbGg 1/8 bbgg bg BG Bg bG
BbGG
bbGG
bbGg
BbGg
Bbgg
bbgg

65. 5. Pleiotropy One gene affects multiple traits
In humans these usually present themselves with disease.
Example: sickle cell disease

66. Human Genetic Disorders
Images from:
Ch. 9 (pg. 176)

67. Genetic Traits and Disorders
Genes that control human traits can be altered (mutated) and then inherited by offspring
Images from:

68. Mutation What is a mutation?
Definition= a change in DNA sequence that affects genetic info The result of some mutations are genetic disorders.
Image from:

69. How are disorders passed or inherited?
Four main ways
Single gene
Multifactorial
Chromosomal abnormality
X-linked

70. Single Gene Disorders Examples . . .
The problem trait is controlled by a single gene and can be passed in a dominant or recessive manner (simple genetic trait)
Examples . . .

71. Single Gene Disorders Examples
Dominant
Achondroplasia
2. Cataracts
3. Polydactyly
Images from:

72. Single Gene Disorders Examples
Recessive
Albinism
2. Sickle Cell Anemia
Images from:

73. Multifactorial Disorders
many
factors
Result from mutations in multiple genes
Environmental factors can also affect the severity/onset of these disorders
Difficult to study and treat

74. Multifactorial Disorders Examples
Hypothyroidism
Alzheimer’s disease
Some cancers (colon, breast, etc.)

75. Chromosomal Abnormality
In these disorders, entire chromosomes or large segments of chromosomes could be missing, duplicated, or otherwise altered.
Image from:

76. Ways chromosomal abnormality can occur:
Nondisjunction
Failure of a chromosome to separate from its homologue during meiosis
One gamete receives an extra copy of a chromosome and the other gamete lacks the chromosome entirely

77. Nondisjunction

78. Nondisjunction
Utah Genetics simulation of how Monosomy/Trisomy develop (click on image)

79. Chromosomal Abnormality (cont.)
Scientists can use karyotypes to identify disorders caused by chromosomal abnormalities.
Example of a normal human male karyotype:

80. Ex. Down Syndrome is caused by three copies of chromosome # 21
Nondisjunction
Ex. Down Syndrome is caused by three copies of chromosome # 21
Image from:

81. Ways chromosomal abnormality can occur:
deletion
Image from:

82. Ways chromosomal abnormality can occur:
duplication
Image from:

83. Ways chromosomal abnormality can occur:
insertion
Image from:

84. Ways chromosomal abnormality can occur:
translocation
Image from:

85. Checkpoint: Analyze Karyotypes
Human?
Male or Female?
Genetic Disorder?
Image from:

86. Checkpoint: Analyze Karyotypes
Human?
Male or Female?
Genetic Disorder?
Image from:

87. Checkpoint: Analyze Karyotypes
Human?
Male or Female?
Genetic Disorder?
Image from:

88. X-Linked Disorders
Disorders in which the mutation or errors are in genes found on the X chromosome
Examples Hemophilia 2. Muscular Dystrophy 3. Red/Green colorblindness
Images from:

89. Sex Determination
In humans, what genetically makes you male or female????
Images from:

90. Gender is determined by our chromosomes
females  XX
males XY
female
male
What can you notice about the difference between the X and Y chromosomes?

91. What do you notice about the difference
between the X and Y chromosomes?
Y chromosome is much smaller.
The Y chromosome carries the “SRY” gene. This gene is called the “sex-determining gene” because it causes male sex organs to develop.
SRY
Images from:

92. X X X XX XX XY XY Y The possible genotypes for gender are XX or XY.
That amounts to 3 Xs and 1 Y.
Why then aren’t there more females than males in the world?
 Complete the Punnett square X X
Results:
Each mating there is a…
50% chance female and % chance male X XX XX XY XY Y

93. Phenotypes are used to infer Genotypes
Pedigree
Definition: A chart which shows the relationship within a family
One of the best ways to study human patterns of inheritance & genetic disease
Phenotypes are used to infer Genotypes

94. Pedigree Basics = normal female = normal male = affected female
= affected male
= affected female
= carrier female
= marriage line
= children

95. Pedigrees can be used to predict if a trait is dominant, recessive, or sex-linked

96. Dominant
At least one parent must show the trait if it is dominant

97. Recessive
Recessive disorder can be passed from any combination of parents, as long as the dominant parent is heterozygous.

98. X-linked
Females can be carriers
More males may be affected