1. Chapter Introduction
Lesson 1 Mendel and His Peas
Lesson 2 Understanding Inheritance

2. Do you agree or disagree?
1. Like mixing paints, parents’ traits always blend in their offspring.
2. If you look more like your mother than you look like your father, then you received more traits from your mother.
3. All inherited traits follow Mendel’s patterns of inheritance.

3. Do you agree or disagree?
4. Scientists have tools to predict the form of a trait an offspring might inherit.
5. Any condition present at birth is genetic.
6. A change in the sequence of an organism’s DNA always changes the organism’s traits.

4. How are traits passed from parents to offspring?

5. GENETICS
What other words
begin with gen- ?

6. Student Traits
Earlobes
Tongue Rolling
Thumbs

7. Mendel and His Peas SWBAT
Explain why Mendel performed cross- pollination experiments
Describe what Mendel concluded about inherited traits

8. Some terms to know…
Gene- hereditary factors that determine your traits (found in your DNA)
Traits- the way something looks or acts (color, size ect)
Genotype: What genes you have TT
Phenotype: What your genes make you look like TT = tall tt= short

9. Early Ideas About Heredity
Heredity is the passing of Genes (traits) from parents to offspring.
Gregor Mendel is known as the father of genetics—the study of how Genes (traits) are passed from parents to offspring.

10. Gregor Mendel- The man who mathematically proved that “it” is actually not in your blood

11. Mendel studied genetics by doing controlled breeding experiments with pea plants.
Attention!
Gregor did all of
his research before we
even knew about DNA!

12. Mendel’s Experimental Methods (cont.)
When a homozygous (true-breeding plant) PP self-pollinates, it always produces offspring with traits that match the parent.
(for example: white flowers that always produce offspring that have white flowers)

13. When Mendel crossed true-breeding or homozygous plants they always gave offspring with the same phenotypes

14. Mendel’s Results
Once Mendel had enough homozygous (PP- purple) and (pp- white) plants for a trait he wanted to test, he cross-pollinated selected plants.
Plants are called hybrids or heterozygous (Pp) if they come from homozygous parent plants with different forms of the same trait. – for example P-purple and p-white

15. Cross-Pollination

16. What is “odd” about the offspring that were produced?
What do you think he did next?

18. Mendel’s Results (cont.)
hybrid
Science Use the offspring of two animals or plants with different forms of the same trait
Common Use having two types of components that perform the same function, such as a vehicle powered by both a gas engine and an electric motor

19. Second-Generation (Hybrid) Crosses

20. Mendel’s Results
Mendel recorded traits of offspring from many hybrid crosses.
Now it is time to
do some ratios!!!

21. Mendel’s Conclusions
Important! – Due to the Mathematical Ratios Mendel concluded that two factors, one from each sperm and one from each egg, control each inherited trait.
A ratio of 3:1 is only seen if there are two hybrid crosses with one of the two traits being dominant!!!

22. Mendel’s Conclusions (cont.)
A dominant trait is a genetic factor that blocks another genetic factor.
A recessive trait is a genetic factor that is blocked by the presence of a dominant factor.

23. Review Questions 1. What is heredity?
2. What did Mendel conclude about sexually reproducing organisms?
3. One of these factors comes from ________ and the other comes from ________.
4. Describe how a flower could be purple but still have a gene for being white!

24. Genetics is the study of how traits are passed from parents to offspring.
Mendel studied genetics by doing cross-breeding experiments with pea plants.

25. Mendel’s experiments with pea plants showed that some traits are dominant and others are recessive.

26. Mendel Song

27. Mendel’s Conclusions (cont.)
How do dominant and recessive factors interact?

28. What method did Mendel use to select which plants pollinated other plants?
A. true breeding
B. self-pollination
C. cross-pollination
D. bees
Lesson 1

29. How many dominant factors does a purple-flowering pea plant have?
B. 1
C. 2
D. 1 or 2
Lesson 1

30. What is the approximate ratio of dominant to recessive expression when both parents are hybrid?
Lesson 1

31. Do Now: Ratios

32. Understanding Inheritance
SWBAT
State what determines the expression of traits
Show how can inheritance be modeled

33. Review: What Controls Traits
Mendel concluded that two factors—one from each parent—control each trait.
Mendel’s “factors” are part of chromosomes which exist as pairs—one chromosome from each parent.
Each cell in an offspring organism contains chromosomes from both parents.

34. What Controls Traits (cont.)
A gene is a section on a chromosome that has genetic information for one trait.
The different forms of a gene are called alleles. Each chromosome has one allele for every gene on it.
The two chromosomes
in an offspring cell may
have the same or
different alleles.

35. Lesson 2

36. What Controls Traits (cont.)
Geneticists call how a trait appears, or is expressed, the trait’s phenotype.
The two alleles that control the phenotype of a trait are called the trait’s genotype.

37. What Controls Traits (cont.)
phenotype
from Greek phainein, means “to show”

38. What Controls Traits (cont.)
When the two alleles of a gene are the same, the genotype is homozygous.
If the two alleles of a gene are different, the genotype is heterozygous.

40. What Controls Traits (cont.)
Scientists use uppercase and lowercase letters as symbols to represent the alleles in a genotype.
How do alleles determine the expression of traits?

41. Modeling Inheritance
A Punnett square is a model used to predict possible genotypes and phenotypes of offspring.

43. A pedigree shows phenotypes of genetically related family members.
Male = square Female = circle

44. 1. How many generations are represented in this chart?
2. How many children were there in the second generation? How many were affected.
3. Is it possible for the dad in G1 to be homozygous dominant? Why?

45. Complex Patterns of Inheritance
SWBAT
A- Differentiate between codominance and incomplete dominance
B- List several environmental factors that can affect gene expression / phenotype

46. Codominance occurs when both alleles can be observed in a phenotype.

47. Sometimes traits appear to be blends of alleles.
Alleles show incomplete dominance when the offspring’s phenotype is a blend of the parents’ phenotypes.

48. Polygenic inheritance occurs when multiple genes determine the phenotype of a trait.

49. Genes and the Environment
The environment can turn on or off certain genes! This changes the organism's phenotype.
In all cases it usually helps the organisms survive in its environment. (if it didn't help the organism probably already died)

50. Mutagens - environmental factors that causes a change in a gene DNA sequence or affects the way a gene functions

51. “Natural” Factors
The three common factors that affect gene expression:
Temperature
Ph (Acidity or Basicity)
Time of year

52. Environment on Genes
A Siamese cat produces darker fur in cooler areas of its body.
The cold environment activates the gene for darker fur!

53. Environment Affecting Gene Expression
Some corn kernels turn bright red in the presence of sunlight!!!

54. Human Skin Color-Tanning
UV light from the Sun turns on the gene to produce melanin
This causes our skin to get darker to protect us from the Sun’s harmful rays!

55. Click on rabbit for video

56. Review Questions
1. Give and example that shows how the environment can affect the phenotype of an organism.
2. What environmental factors affect phenotype?
3. Does having a gene that predisposes a person to a disease such as heart disease or diabetes mean the person is destined to develop the disease?

57. Humans
We know that cancer and heart disease “runs” in certain families
Does this mean that you will defiantly get the disease?-- - Absolutely not!
What you do with and put into your body will affect what those genes do. That would be you body’s environment.
Ex: If cancer runs in your family and you chose to eat healthy, use sun block, not smoke and exercise your chances of getting it are very low! That is supplying your body with the “Right Environment.”

58. The genes for traits are located on chromosomes.

59. Geneticists use Punnett squares to predict the possible genotypes and phenotypes of offspring.
In polygenic inheritance, traits are determined by more than one gene and have many possible phenotypes.
Lesson 2

61. Genetics will now be broken up into two smaller units
(everything before this is Gen1 and everything after this is Gen2)

63. Now complete your graphic organizer

65. Inherited genes are the basis of an organism’s traits.

66. Lesson 1: Mendel and His Peas
Mendel performed cross-pollination experiments to track which traits were produced by specific parental crosses.
Mendel found that two factors—one from a sperm cell and one from an egg cell—control each trait.
Dominant traits block the expression of recessive traits. Recessive traits are expressed only when two recessive factors are present.

67. Lesson 2 Review What is the name for different forms of a gene?
A. alleles
B. phenotypes
C. genotypes
D. chromosomes
Lesson 2

68. Review
What is the genotype when two alleles of a gene are the same?
A. heterozygous
B. dominant
C. homozygous
D. recessive
Lesson 2

69. Review
What occurs when both alleles can be observed in a phenotype?
A. incomplete dominance
B. homozygous
C. polygenic
D. codominance
Lesson 2

70. Review According to Mendel, how many factors controlled each trait?
B. 2
C. 3
D. 4

71. Review Which of the following describes alleles that control a trait?
A. phenotype
B. codominance
C. genotype
D. polygenic inheritance

72. Understanding Inheritance
Phenotype describes how a trait appears.
Genotype describes alleles that control a trait.
Punnett squares and pedigrees are tools to model patterns of inheritance.
Many patterns of inheritance, such as codominance and polygenic inheritance, are more complex than Mendel described.

73. Review
If parents have the genotypes RR and Rr, what percentage of offspring will have a Rr genotype?
A. 25%
B. 50%
C. 75%
D. 100%

74. Review
In fruit flies, the allele for red eyes (R) is dominant over the allele for white eyes (r). If parents have the genotypes Rr and Rr, what percentage of offspring will have red eyes?
A. 25 percent C. 75 percent
B. 50 percent D. 100 percent

75. Review Heredity is associated with which of the following?
A. chromosomes
B. genes
C. genotype
D. all of the above

76. Review
Which occurs when multiple genes determine the phenotype of a trait?
A. polygenic inheritance
B. mutation
C. environmental influence
D. codominance