Genetics

Colorado Agriscience Curriculum

Objectives

• Explain Gregor Mendel’s contribution to

the scientific community;

• Describe the interaction between

chromosomes, genes, traits, and alleles;

• Differentiate between genotype and

phenotype;

Unit 4, Lesson 11 Mendal and Genetics

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Objectives

• List the 6 fundamental types of mating;

• Workout punnett squares for one and two

pair of contrasting traits; and

• Calculate phenotypic and genotypic ratios.

Unit 4, Lesson 11 Mendal and Genetics

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Unit 4, Lesson 11 Mendal and Genetics

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I. Gregor Mendel

• A) Geneticist who first developed the rules

to predicting the pattern of heredity

– 1) Monk who did experiments with peas

• B) Heredity

– 1. passing of traits such as coat color, polled

or horned, height, etc. from parents to

offspring

Unit 4, Lesson 11 Mendal and Genetics

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I. Gregor Mendel

• C) Breeding Generations

– 1. P Generation

• a) parental generation

– 2. F1 Generation

• a) Filial Generation

• b) 1st offspring of P Generation

– 3. F2 Generation

• a) 2nd Filial Generation

• b) offspring of F1 Generation

Unit 4, Lesson 11 Mendal and Genetics

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I. Gregor Mendel

• D)3 Steps of Mendel’s Experiment

– 1. P Generation

• a) Allowed each variety to self pollinate for several

generations

– 1. ensure that all offspring would display only one form of a

particular trait (flower color)

– 2. Crossbred the two strains of the P

generation

• - Recorded Data

• - Resulted in all purple flowers

Unit 4, Lesson 11 Mendal and Genetics

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I. Gregor Mendel

• D)3 Steps of Mendel’s Experiment

– 3. Allowed the F1 Generation to self-pollinate

• a) Resulted in the F2 Generation

• b) 1 out of every four flowers was white.

Unit 4, Lesson 11 Mendal and Genetics

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I. Gregor Mendel

Unit 4, Lesson 11 Mendal and Genetics

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II. Traits

• A) Chromosomes and Genes are in pairs

– 1. One chromosome is contributed by each parent

– 2. Chromosome Locus

• a) site where a gene is found on a chromosome

• B) Traits

– 1. For each inherited trait an individual has, there are

two copies of that gene ( 1 from each parent)

– 2. Genes are what causes traits to appear

• a) each version is called an allele

• a) eye color, coat color, marbling, ribeye area, etc.

Unit 4, Lesson 11 Mendal and Genetics

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Unit 4, Lesson 11 Mendal and Genetics

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III. Genes Located on

Corresponding Homologous

Chromosomes may: • A) Correspond to each other

– 1. homozygous

• B) Differ from each other

– 2. heterozygous

• C) Genes on corresponding chromosomes

that control the same trait are called

alleles

Unit 4, Lesson 11 Mendal and Genetics

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IV: Alleles

• A) Homozygous (BB or bb)

– 1. both alleles are the same

• B) Heterozygous (Bb)

– 1. two alleles are different

• C) The dominant (capital) allele is always expressed when it is present

• D) The recessive allele is only expressed when both copies of the gene are recessive

Unit 4, Lesson 11 Mendal and Genetics

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V: Genotype and Phenotype

• A) Genotype

– 1. amount, order, and type of genes an

individual has

– 2. genetic make-up of an individual

• B) Phenotype

– 1. Physical traits an individual possesses

– 2. Doesn’t take into account masked traits

only expressed or dominant traits

Dominant and Recessive Genes

Colorado Agriscience Curriculum

Unit 4, Lesson 12 Dominant and

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I. Monohybrid Crosses

• A. Three class genotypes

– 1. Homozygous Dominant = BB

– 2. Homozygous Recessive = bb

– 3. Heterozygous = Bb

• B. B = Black & b = Red

• C. Six possible crosses:

BB x BB, BB x Bb, BB x bb, Bb x Bb, Bb x bb, bb x bb

Unit 4, Lesson 12 Dominant and

Recessive PP 16

I. Predicting Ratios

• Homozygous x Homozygous

• A. Genotype – 2. Results in a

homozygous dominant zygote

• B. BB x BB – Phenotype:

– 1. Each parent can only contribute a dominant gene

B B

B BB BB

B BB BB

Unit 4, Lesson 12 Dominant and

Recessive PP 17

II. Predicting Ratios

Homozymous x Heterozygous

• E. BB x Bb

– 1. Genotypic Ratio

• 2 BB : 2 Bb

– 2. Phenotypic Ratio

• a) 4 Black color

B B

B BB BB

b Bb Bb

Unit 4, Lesson 12 Dominant and

Recessive PP 18

III. Predicting Ratios

• Homozygous x

Homozygous

• F. BB x bb

– Genotypic ratio:

• 0BB : 4Bb

• All offspring will be

heterozygous

– Phenotypic ratio: 4

black coat : 0 red

coat

B B

b Bb Bb

b Bb Bb

Unit 4, Lesson 12 Dominant and

Recessive PP 19

IV. Predicting Ratios

• G. Bb x Bb

– 1. Phenotypic Ratio

• a) 3 black to 1 red or

3:1

– 2. Genotypic Ratio

• a) 1BB: 2Bb: 1bb

B b

B BB Bb

b Bb bb

Unit 4, Lesson 12 Dominant and

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V. Predicting Ratios

• H. Bb x bb

– 1. Genotypic Ratio

• a) 2Bb: 2bb

– 2. Phenotypic Ratio

• a) 2 black to 2 red

b b

B Bb Bb

b bb bb

Unit 4, Lesson 12 Dominant and

Recessive PP 21

VI. Predicting Ratios

• B. Homozygous x Homozygous

• . bb x bb - All will be red

• Genotypic Ratio – 4bb : 0

• Phenotypic Ratio – 4 red coats : 0 black

coats

b b

b bb bb

b bb bb

Unit 4, Lesson 12 Dominant and

Recessive PP 22

II. Multiple Gene Pairs

• A. Mating – 1. B = Black & b = Red

– 2. P = Polled & p = horned

• B. Bull – 1. BbPp

• C. Cow – 1. BbPp

• D. What will the phenotypic & genotypic ratios be?

Unit 4, Lesson 12 Dominant and

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II. Multiple Gene Pairs

PB Pb pB pb

PB PPBB PPBb PpBB PpBb

Pb PPBb PPbb PpBb Ppbb

pB PpBB PpBb ppBB ppBb

pb PpBb Ppbb ppBb ppbb

Unit 4, Lesson 12 Dominant and

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II. Multiple Gene Pairs

• E. Genotypic Ratio

– 1. 1 PPBB: 2 PPBb: 1 PPbb: 2 PpBB: 4 PpBb: 2 Ppbb: 2 ppBb: 1ppbb

• F. Phenotype

– 1. 9 polled and black

– 2. 3 polled and red

– 3. 3 horned and black

– 4. 1 horned and red

Unit 4, Lesson 12 Dominant and

Recessive PP 25

Worksheet 1

B b

B

B

B B

B

B

B B

b

b

B b

B

b

Unit 4, Lesson 12 Dominant and

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Worksheet 2

B b

b

b

b b

b

b

Unit 4, Lesson 12 Dominant and

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Worksheet 3

PB Pb pB pb

PB

Pb

pB

pb