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4-2 Notes – Understanding Inheritance Chapter 4, Lesson 2

4-2 Notes – Understanding Inheritance Chapter 4, Lesson 2

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Page 1: 4-2 Notes – Understanding Inheritance Chapter 4, Lesson 2

4-2 Notes – Understanding Inheritance

Chapter 4, Lesson 2

Page 2: 4-2 Notes – Understanding Inheritance Chapter 4, Lesson 2

Punnett Squares

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

• If the genotypes of the parents are known, the genotypes and phenotypes of the offspring can be predicted.

Page 3: 4-2 Notes – Understanding Inheritance Chapter 4, Lesson 2

Punnett SquaresB = black furb = brown fur

Page 4: 4-2 Notes – Understanding Inheritance Chapter 4, Lesson 2

Punnett SquaresB = black furb = brown fur

Female = BB

Male = bb

Page 5: 4-2 Notes – Understanding Inheritance Chapter 4, Lesson 2

Punnett SquaresB = black furb = brown fur

Female = BB

Male = bb

Page 6: 4-2 Notes – Understanding Inheritance Chapter 4, Lesson 2

Punnett SquaresB = black furb = brown fur

Female = BB

Male = bb

B

Page 7: 4-2 Notes – Understanding Inheritance Chapter 4, Lesson 2

Punnett SquaresB = black furb = brown fur

Female = BB

Male = bb

B B

Page 8: 4-2 Notes – Understanding Inheritance Chapter 4, Lesson 2

Punnett SquaresB = black furb = brown fur

Female = BB

Male = bb

B B

b

Page 9: 4-2 Notes – Understanding Inheritance Chapter 4, Lesson 2

Punnett SquaresB = black furb = brown fur

Female = BB

Male = bb

B B

b

b

Page 10: 4-2 Notes – Understanding Inheritance Chapter 4, Lesson 2

Punnett SquaresB = black furb = brown fur

Female = BB

Male = bb

B B

b

b

B b

Page 11: 4-2 Notes – Understanding Inheritance Chapter 4, Lesson 2

Punnett SquaresB = black furb = brown fur

Female = BB

Male = bb

B B

b

b

B b B b

Page 12: 4-2 Notes – Understanding Inheritance Chapter 4, Lesson 2

Punnett SquaresB = black furb = brown fur

Female = BB

Male = bb

B B

b

b

B b B b

bB

Page 13: 4-2 Notes – Understanding Inheritance Chapter 4, Lesson 2

Punnett SquaresB = black furb = brown fur

Female = BB

Male = bb

B B

b

b

B b B b

bB B b

Page 14: 4-2 Notes – Understanding Inheritance Chapter 4, Lesson 2

Punnett SquaresB = black furb = brown fur

Female = BB

Male = bb

B B

b

b

B b B b

bB B b

black black

black black

Page 15: 4-2 Notes – Understanding Inheritance Chapter 4, Lesson 2

Punnett Squares (5:00)

Page 16: 4-2 Notes – Understanding Inheritance Chapter 4, Lesson 2

One-Trait Model

• A cross between two homozygous pea plants: one with yellow seeds (YY) and one with green seeds (yy).

Page 17: 4-2 Notes – Understanding Inheritance Chapter 4, Lesson 2

One-Trait Model

• All offspring have the heterozygous genotype (Yy).

• All offspring have the yellow phenotype because Y is dominant to y.

• We call these offspring hybrid because they have one of each type of allele.

Page 18: 4-2 Notes – Understanding Inheritance Chapter 4, Lesson 2

Two-Trait Model

Page 19: 4-2 Notes – Understanding Inheritance Chapter 4, Lesson 2

Two-Trait Model

• A cross between two heterozygous genotypes (Yy and Yy)

Page 20: 4-2 Notes – Understanding Inheritance Chapter 4, Lesson 2

Two-Trait Model

• The offspring would have three different genotypes and two phenotypes.

Page 21: 4-2 Notes – Understanding Inheritance Chapter 4, Lesson 2

Two-Trait Model

FF Ff

Ff ff

F = frecklesf = no freckles

freckles freckles

freckles no freckles

• Cross a freckled Dad (Ff) with a freckled Mom (Ff).

Page 22: 4-2 Notes – Understanding Inheritance Chapter 4, Lesson 2

Two-Trait Model

Genotypes:

___% are FF

___% are Ff

___% are ffFF Ff

Ff ff

F = frecklesf = no freckles

freckles freckles

freckles no freckles

25

50

25

Page 23: 4-2 Notes – Understanding Inheritance Chapter 4, Lesson 2

Two-Trait Model

Phenotypes:

___% have freckles

___% have no freckles

F = frecklesf = no freckles

FF Ff

Ff ff

freckles freckles

freckles no freckles

75

25

Page 24: 4-2 Notes – Understanding Inheritance Chapter 4, Lesson 2

Pedigrees

• All the genetically related members of a family are part of a family tree.

• A pedigree shows genetic traits that were inherited by members of a family tree.

• Pedigrees are important tools for tracking complex patterns of inheritance and genetic disorders in families.

Page 25: 4-2 Notes – Understanding Inheritance Chapter 4, Lesson 2

Pedigrees

• This pedigree chart shows three generations of a family.

Page 26: 4-2 Notes – Understanding Inheritance Chapter 4, Lesson 2

Pedigrees Fill in the key!

Page 27: 4-2 Notes – Understanding Inheritance Chapter 4, Lesson 2

Incomplete Dominance

• This is a blend of the parents’ phenotypes.

Page 28: 4-2 Notes – Understanding Inheritance Chapter 4, Lesson 2

Codominance

• This is when both alleles can be observed in the phenotype because both are dominant.

• The human blood type AB is an example of codominance.

Page 29: 4-2 Notes – Understanding Inheritance Chapter 4, Lesson 2

Codominance

Page 30: 4-2 Notes – Understanding Inheritance Chapter 4, Lesson 2

Codominance

Page 31: 4-2 Notes – Understanding Inheritance Chapter 4, Lesson 2

Multiple Alleles

• Some genes have more than two alleles, or multiple alleles.

• The human ABO blood group is determined by multiple alleles as well as codominance.

• There are three different alleles for blood types: IA, IB, and i.

Page 32: 4-2 Notes – Understanding Inheritance Chapter 4, Lesson 2

Multiple Alleles

Page 33: 4-2 Notes – Understanding Inheritance Chapter 4, Lesson 2

Sex-Linked Inheritance• Chromosomes X and Y are the sex

chromosomes - they contain the genes that determine sex (male or female).

Page 34: 4-2 Notes – Understanding Inheritance Chapter 4, Lesson 2

Sex-Linked Inheritance• Except for sperm and eggs, each cell in a

male has an X and a Y chromosome, and each cell in a female has two X chromosomes.

Page 35: 4-2 Notes – Understanding Inheritance Chapter 4, Lesson 2

Sex-Linked Inheritance• A recessive phenotype is observed in a male

when a one-allele gene on his X chromosome has a recessive allele. There is no allele on his Y chromosome to “mask” the recessive allele.

Page 36: 4-2 Notes – Understanding Inheritance Chapter 4, Lesson 2

Sex-Linked Inheritance

Page 37: 4-2 Notes – Understanding Inheritance Chapter 4, Lesson 2

Sex-Linked InheritanceIn this family, the grandmother’s genome included the color blindness allele.

Page 38: 4-2 Notes – Understanding Inheritance Chapter 4, Lesson 2

Sex-Linked Inheritance• Example: red-green

colorblindness

A carrier has one recessive allele and one dominant allele for a trait. They don’t have the trait but can pass it on to offspring.

Page 39: 4-2 Notes – Understanding Inheritance Chapter 4, Lesson 2

Polygenic Inheritance

• This is when more than one gene determines the phenotype of a trait.

• Many phenotypes are possible when possible when polygenic inheritance determines a trait.

• Examples: hair color, height, skin color

Page 40: 4-2 Notes – Understanding Inheritance Chapter 4, Lesson 2

Human Genetic Disorders

• If a change occurs in a gene, the organism with the mutation may not be able to function as it should.

• An inherited mutation can result in a phenotype called a genetic disorder.

Page 41: 4-2 Notes – Understanding Inheritance Chapter 4, Lesson 2
Page 42: 4-2 Notes – Understanding Inheritance Chapter 4, Lesson 2
Page 43: 4-2 Notes – Understanding Inheritance Chapter 4, Lesson 2
Page 44: 4-2 Notes – Understanding Inheritance Chapter 4, Lesson 2
Page 45: 4-2 Notes – Understanding Inheritance Chapter 4, Lesson 2

Chris Sutter

Page 46: 4-2 Notes – Understanding Inheritance Chapter 4, Lesson 2

Genes and the Environment

• An organism’s environment can affect its phenotype.– Genes affect heart disease, but so do diet and

exercise.– Genes affect skin color, but so does exposure to

sunlight.

Page 47: 4-2 Notes – Understanding Inheritance Chapter 4, Lesson 2

Genes and the Environment

Siamese cats have a gene that codes for darker pigments - this gene is more active at low temperatures. Parts of the body that are colder (ears, feet, tail) will develop the darker pigmentation of the Siamese cats.

Page 48: 4-2 Notes – Understanding Inheritance Chapter 4, Lesson 2

Punnett squares model the ____ of offspring.

A genotypes

B phenotypes

C genotypes and phenotypes

D genes

4.2 Understanding Inheritance

Page 49: 4-2 Notes – Understanding Inheritance Chapter 4, Lesson 2

What is the term for when alleles produce a phenotype that is a blend of the parents’ phenotypes?

A incomplete dominance

B codominance

C multiple alleles

D polygenic inheritance

4.2 Understanding Inheritance

Page 50: 4-2 Notes – Understanding Inheritance Chapter 4, Lesson 2

How many Y chromosomes do females have?

A 0

B 1

C 2

D 4

4.2 Understanding Inheritance

Page 51: 4-2 Notes – Understanding Inheritance Chapter 4, Lesson 2

What is a good example of a trait that is determined by multiple alleles?

A color of camellia flowers

B human AB blood type

C color blindness

D human ABO blood group

Page 52: 4-2 Notes – Understanding Inheritance Chapter 4, Lesson 2

Why are male humans more likely to be color-blind than females?

A maternal inheritance

B sex-linked inheritance

C polygenic inheritance

D incomplete dominance

Page 53: 4-2 Notes – Understanding Inheritance Chapter 4, Lesson 2

If two plants with genotypes Mm are crossed, what percent of the offspring will have phenotype M?

A 0%

B 25%

C 75%

D 100%

SCI 2.d

Page 54: 4-2 Notes – Understanding Inheritance Chapter 4, Lesson 2

What is the term for when more than one gene determine a trait?

A incomplete dominance

B multiple alleles

C polygenic inheritance

D sex-linked inheritance

SCI 2.c, 2.d

Page 55: 4-2 Notes – Understanding Inheritance Chapter 4, Lesson 2

What type of genetic disorder is hemophilia?

A dominant

B X-linked recessive

C codominant

D recessive

SCI 2.d

Page 56: 4-2 Notes – Understanding Inheritance Chapter 4, Lesson 2

4-2 Vocab – Understanding Inheritancetext p. 182-190

1. Punnett square

2. pedigree

3. incomplete dominance

4. codominance

5. multiple alleles

6. sex chromosome

7. polygenic inheritance

8. genetic disorder

Page 57: 4-2 Notes – Understanding Inheritance Chapter 4, Lesson 2

1. Cross a tall plant (Tt) with a tall plant (Tt).

T = tall, t = short

_____ % tall

_____ % short

Under each genotype, write the correct phenotype.

Page 58: 4-2 Notes – Understanding Inheritance Chapter 4, Lesson 2

2. Tall plant (TT) with short plant (tt).

_____ % tall

_____ % short

Page 59: 4-2 Notes – Understanding Inheritance Chapter 4, Lesson 2

3. Short plant (tt) with tall plant (Tt).

_____ % tall

_____ % short

Page 60: 4-2 Notes – Understanding Inheritance Chapter 4, Lesson 2

4. Tall plant (TT) with tall plant (Tt).

_____ % tall

_____ % short

Page 61: 4-2 Notes – Understanding Inheritance Chapter 4, Lesson 2

1. Cross a tall plant (Tt) with a tall plant (Tt).

T = tall, t = short

_75__ % tall

_25__ % short

T t

T

t

TTtall

Tttall

Tttall

ttshort

Page 62: 4-2 Notes – Understanding Inheritance Chapter 4, Lesson 2

2. Tall plant (TT) with short plant (tt).

_100__ % tall

_0__ % short

T T

t

t

Tttall

Tttall

Tttall

Tttall

Page 63: 4-2 Notes – Understanding Inheritance Chapter 4, Lesson 2

3. Short plant (tt) with tall plant (Tt).

_50__ % tall

_50__ % short

t t

T

t

Tttall

Tttall

ttshort

ttshort

Page 64: 4-2 Notes – Understanding Inheritance Chapter 4, Lesson 2

4. Tall plant (TT) with tall plant (Tt).

_100__ % tall

_0__ % short

T T

T

t

TTtall

TTtall

Tttall

Tttall