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HeredityHeredity

Holt Biology

Chapter 8, pgs. 170-171

By

Bettina Loell-Hull

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Anticipatory SetAnticipatory Set

Anticipation Guide: Biology Standard 3a, (7b)

(phonotype, genotype, heredity and Punnett Square)

Instructions:

Before the lesson, read the questions and circle T or F in the left hand column. After lesson, re-read the question and circle T or F in the right hand column.

#

Before

Questions

After

1 T / F A child receives one allele or version of a trait from each parent.

T / F

2 T / F

Some children don’t get their genes from their parents because they do not look like their parents.

T / F

3 T / F An allele is a version of a gene for a trait. T / F

4 T / F The dominant trait is the expressed version of a gene or the trait that is visible in an individual. T / F

5 T / F The recessive trait will always show in an individual.

T / F

6 T / F Genotype refers to the look of an individual. T / F

7 T / F Phenotype refers to the genetic make-up of an individual.

T / F

8 T / F If a child has blue eyes and both parents have brown eyes, the baby was adopted.

T / F

9 T / F The allele for blond hair is dominant. T / F

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Studying HeredityStudying HeredityUsing the Punnett SquareUsing the Punnett Square

http://www.dailymail.co.uk/news/article-377839/Black-white-twins.html

Compare and Contrast the TwinsCompare and Contrast the Twins

Same parents

Each parent has 1 allele for light & 1 allele dark skin.

Each parent has 1 brown & 1 blue allele for eye color.

fraternal twins

1-dark skin (1 or 2 allele(s) for dark skin

2-brown eyes (1 or 2 allele(s) for brown eyes)

1-light skin (2 alleles for light skin)

2-blue eyes (2 alleles for blue eyes)

3-brown hair (1 or 2 allele(s) for brown hair)

3-blond hair (2 alleles

for blond hair)

Each parent has 1 allele for brown hair & 1 allele for

blond hair.

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Anticipatory SetAnticipatory Set

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Heredity and Eye ColorHeredity and Eye Color

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The Punnett Square Calculates the The Punnett Square Calculates the Possibilities of the Children’s LooksPossibilities of the Children’s Looks

B b

B BB Bb

b Bb bb

Mother

Fat

her

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Odds of Dark Hair vs. White HairOdds of Dark Hair vs. White Hair

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Homozygous cross and Homozygous cross and Heterozygous CrossHeterozygous Cross

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Standard 3a:Standard 3a:• Students know how the genotypes of the

parents may be expressed as phenotypes in their offspring.

• Students relate the ratios that Mendel observed in his crosses to his data and to examples of their own.

Phenotype (F1 generation 100 % = 4/4)

Phenotype (F2 generation 75% to 25% = 3/1)

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1. dominant 2. recessive 3. phenotype

4. genotype 5. monohybrid cross

6. homozygous

7. heterozygous 8. allele 9. Punnett square

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1. Dominant (adjective)1. Dominant (adjective)

• Expressed form of the character trait.

• For example the color of a flower may be purple and not white because purple is dominant.

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2. Recessive (adjective)2. Recessive (adjective)

• The trait that is not expressed when the dominant form of the trait is present.

Ex.: In this case, the baby has blue eyes because she has two recessive alleles for blue eyes.

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3 Phenotype (noun)3 Phenotype (noun)

• A phenotype is a living thing’s appearance or other detectable characteristic that results from the living thing’s genotype and the environment.

• For example: the color of a flower or seed

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4 Genotype (noun)4 Genotype (noun)

• The entire genetic makeup of an organism- its DNA• Or the combination of genes for one

specific trait.

•For example, the color of the seed pod is green but the genetic make-up of it is yellow and green.

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5-Monohybrid Cross (noun)5-Monohybrid Cross (noun)

• A cross in which each parent displays a different form of one allele.

• For example: seed color (YY or yy)

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6-Homozygous (adjective)6-Homozygous (adjective)

• Describes an individual that has identical alleles for a trait on both gametes.

• Example: PP or pp for color of flower.

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7-Heterozygous (adjective)7-Heterozygous (adjective)

• Describes an individual that has two different alleles for a trait.

• For example, a flower may look purple but has the alleles Pp for flower color.

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8-Allele (noun)8-Allele (noun)

• An allele is one of the alternative forms of a gene that determines a characteristic, such as hair color.

Example: the alleles for hair color may be black or blond.

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9-Punnett Square (noun)9-Punnett Square (noun)

• A Punnett square is a graphic representation used to predict the chances that the offspring will inherit an allele for a trait.

What are the chances of a yellow offspring if yellow is dominant? 100%

1-Dominant A-Describes an individual who has two different alleles for a trait.

2-Recessive B-graphic representation used to predict chances of offspring to inherit allele of a trait

3-phenotype C- The trait that is not expressed when the dominant form of the character is present.

4-genotype D- Describes individual with identical alleles for a trait.

5-monohybrid cross

E-the combination of genes for one specific trait.

6-homozygous F- a thing’s or person’s appearance

7-heterozygous G- Expressed form of character trait.

8-allele H-A cross in which each parent displays a different form of one character trait.

9-punnett square I- one of the alternative forms of a gene.

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Solution to QuizSolution to Quiz

1 G

2 C

3 F

4 E

5 H

6 D

7 A

8 I

9 B HomeVideo on

Punnett Square

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VideoVideo

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Video on Heredity Video on Heredity How to use the How to use the Punnett SquarePunnett Square

to to Calculate the Odds Calculate the Odds of the Phenotype (looks) of Offspringof the Phenotype (looks) of Offspring

• Gregor Mendel's Rules of Heredity—Demonstration of impact that Parents Genotype has on Offspring’s Phenotype Using Punnett Squares

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What did we learn from the video?What did we learn from the video?

• We learned how to use the Punnett Square to calculate the odds of a certain phenotype in the offspring.

• We learned how to create a Monohybrid Cross 1. with homozygous parents

2. with heterozygous parents

1 2

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Modeling 1 Modeling 1

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Monohybrid Cross – Monohybrid Cross – with with Homozygous Bunny ParentsHomozygous Bunny Parents

f f

F F f

F f

F F f F f

Black is dominant

Black Fur White Fur

4/4=1=100% 0/4=0=0%

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Modeling 2 Modeling 2

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Monohybrid Cross (one trait) – Monohybrid Cross (one trait) – with with Heterozygous Bunny ParentsHeterozygous Bunny Parents

F f

F F F

F f

f F f f f

Black is dominant

Black Fur White Fur

¾ = 75% =.75 ¼ = 25% =.25

Offspring’s Phenotype

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Guided Practice 1Guided Practice 1

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Monohybrid Cross – with Monohybrid Cross – with HomozygousHomozygous ParentsParents who have who have

blue eyesblue eyes and and brown eyes.brown eyes. b b

B B b

B b

B B b B b

Brown is dominant

Brown Eyes Blue Eyes

4/4 =100% =1 0/4=0%=0

Offspring’s Phenotype

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Guided Practice 2Guided Practice 2

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Monohybrid cross – Monohybrid cross – with with Heterozygous ParentsHeterozygous Parents Who both have Who both have Brown EyesBrown Eyes..

B b

B B B

B b

b B b b b

Brown is dominant

Brown Eyes Blue Eyes

¾ =75% =.75 ¼ =25% =.25

Offspring’s Phenotype

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Independent Practice 1Independent Practice 1

Monohybrid cross with homozygous (BB or bb) parents

• Predict the phenotype of the offspring resulting from a cross of a white haired dog with a black haired dog.

• Make black hair (B) dominant and white hair (b) recessive.

• The white dog is homozygous recessive.• The black dog is homozygous dominant.• Write the gametes that each parent can.

contribute as row and column labels.• What does the offspring look like? • State your answer in %, fraction, and decimals for each phonotype.

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Monohybrid Cross – with Monohybrid Cross – with HomozygousHomozygous Parents Parents (dogs) who have (dogs) who have

white furwhite fur and and black furblack fur..

Black is dominant

Offspring’s PhenotypeBlack Fur,x/4, %, x.xx White Fur x/4, %, x.xx

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Monohybrid Cross – with Monohybrid Cross – with HomozygousHomozygous Parents Parents (dogs) who have (dogs) who have

white furwhite fur and and black furblack fur.. b b

B B b

B b

B B b B b

Black is dominant

Black Fur White Fur

4/4 = 100% =1 0/4 =0% =0

Offspring’s Phenotype

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Independent Practice 2Independent Practice 2

Monohybrid cross with Monohybrid cross with heterozygousheterozygous ((BBbb and and BBb)b) parents parents

• Predict the phenotype of the offspring of a cross of a black haired dog with a black haired dog (black hair is dominant that is why both dogs are black).

• Both dogs are heterozygous for hair color (Bb and Bb).

• Write the gametes that each parent can contribute as row and column labels.

• What does the offspring look like? • State your answer in %, fraction, and decimals for

each phonotype.

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Monohybrid Cross – with Monohybrid Cross – with HeterozygousHeterozygous Parents (dogs) Parents (dogs)

who both havewho both have black furblack fur..

Black is dominant

Offspring’s PhenotypeBlack Fur,x/4, %, x.xx White Fur x/4, %, x.xx

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Monohybrid Cross – with Monohybrid Cross – with HeterozygousHeterozygous Parents (dogs) Parents (dogs)

who both havewho both have black fur.black fur.

B b

B B B

B b

b B b bb

Black is dominant

Black Fur White Fur

¾ =75% =.75 ¼ =25% =.25

Offspring’s Phenotype

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End of Lesson 1End of Lesson 1

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Modeling

Punnett Squares / Monohybrid Cross (1 traits = fur color) homozygous parents Phenotype (looks) of offspring

Fraction /4 /4 Percent % %

Decimal . .

heterozygous parents Phenotype (looks) of offspring

Fraction /4 /4

Percent % %

Decimal . .

1. Escape

2. Double Click on document to open in word and see worksheets

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Release test question:

Ch c

Ch ChCh Chcc Chc cc

Chc Produces offspring that is least likely to survive.

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ResourcesResourcesTypes of Learnershttp://www.chaminade.org/inspire/learnstl.htm

Video on Punnett Square and monohybrid crosses with homozygous parents and heterozygous parents.

Gregor Mendel's Rules of Heredity—Demonstration of impact that Parents Genotype has on Offspring’s Phenotype Using Punnett SquaresHolt Biology, chapter 8, pages 170-171