lesson question€¦ · slide instruction introduction to heredity heredity and genetics ... •...

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Warm-Up Introduction to Heredity

Lesson Question

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WK2 Words to KnowWrite the letter of the definition next to the matching word as you work through the lesson. You may use the glossary to help you.

homozygous

alleles

genetics

heterozygous

heredity

genotype

recessive

phenotype

dominant

A. the study of heredity

B. having two identical alleles for a particular trait

C. the different forms of a gene for a given trait

D. an organism’s allele combination

E. the passing of traits from parents to offspring

F. having two different alleles for a particular trait

G. describes the allele that when present, masks the appearance of the recessive allele

H. describes the allele that is masked when the dominant allele is present

I. the physical appearance or characteristics seen in an organism

Lesson Goals

Examine the contributions made by Gregor Mendel to the field of genetics.

Explain how traits are inherited.

Distinguish dominant and

alleles.

Differentiate between

and phenotype.


Warm-Up Introduction to Heredity

DNA

• DNA is found in the of cells.

• DNA stores an organism’s code.

• DNA is wrapped around and condensed into chromosomes.

• Genes are used as a set of instructions to produce proteins.

• Proteins affect the and function of organisms.


2Slide

Introduction to HeredityInstruction

Heredity and Genetics

• Heredity is the passing of traits from to .

• Genetics is the study of heredity.

• is known as the “Father of Genetics.”

Pea Plant Traits

Mendel noticed that peas had many different .

Seed color

Green or yellow

Seed shape

or round

Pod color

Yellow or green

Pod shape

or bumpy



2Slide

Pea Plant Traits

Mendel noticed that peas had many different characteristics.

Plant

Tall or short

Flower color

Purple or

Flower

Middle or top of stem

Pea Plants Experiments

• Gregor Mendel mated plants with the he wanted to study.

• He took (male reproductive cells) from one plant and joined

them with (female reproductive cells) from a different plant.

• Example: Green pea x yellow pea

Circle one male reproductive structure in the following diagram.

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4Slide

Results of Mendel’s Experiment

Parents

First-generation offspring First-generation offspring

Parents

Mendel determined that if he crossed plants with the same

characteristics—for example, the same colored peas—the had the same characteristics as well.

Results of Mendel’s Experiment

First-generation offspring Second-generation offspring

offspring

He allowed the from anther of one plant to fall on the

of the same plant.



7Slide

Mendel’s Factors

Based on his results, Mendel hypothesized that there were things, which he called

“ ,” in pea plants that allowed the plants to traits.

offspring

Parents

First-generation offspring

First-generation offspring

Alleles

• Alleles are the different forms of a

for a given .

• The gene for seed color has forms.

• An allele that codes for yellow

.

• An allele that codes for green seeds.

Circle the allele that codes for green seeds.



7Slide

Inheritance of Traits

• Characteristics that are coded for by genes, traits, can be inherited.

• One allele for every gene in an is inherited from each

.

• When each parent provides a different allele of a gene, the offspring is

for that particular trait.

• When both parents provide the same allele of a gene, the offspring is

for that trait.

Characteristics That Are Not Inherited

• Characteristics that are developed due to factors in the cannot be inherited.

• Knowledge gained through

• Muscles developed through exercise

• learned through practice

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12Slide

Dominant and Recessive

• A dominant allele is an allele that when present,

the appearance of the recessive

allele.

• A recessive allele is an allele that is masked when

the dominant allele is .

Circle the recessive allele in the following diagram.

Dominant and Recessive Traits

Trait Dominant Recessive

Seed color Yellow Green

Seed Round Wrinkled

Pod Green Yellow

Pod shape Smooth Bumpy

Plant height Short

Flower color Purple White

Flower Middle of stem Top of stem



14Slide

Genotype

• Genotype is an organism’s combination.

• Capital letter for the allele

• Lowercase letter for the recessive allele

Circle the gene for seed color with a recessive allele.

Phenotype

Phenotype is the physical appearance or seen in an organism.

Circle the seed with both recessive alleles in the diagram.

Genotype: YY

Phenotype: yellow

Genotype: Yy

Phenotype: yellow

Genotype: yy

Phenotype: green


Summary Introduction to Heredity

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Answer

Review: Key Concepts

• Gregor Mendel, the Father of Genetics, used pea plants to study heredity.

• There are in organisms that affect the traits of the organism.

• These factors are passed from parent to offspring.

• One factor is contributed by one parent, and the other factor is contributed by the other parent.

• The combination of these factors affects how a is observed.

Lesson Question How are traits passed from one generation to the next?

2Slide



Review: Key Concepts

• Traits are passed from one generation to the next when the material of the parents is combined.

• Each parent contributes one for a trait to the offspring.

• Alleles can either be dominant or recessive.

• A dominant allele is an allele that when present, masks the appearance of the recessive allele.

• A allele is an allele that is masked when the dominant

allele is present.

• The genetic makeup of an organism affects its characteristics.

• Genotype is an organism’s allele combination.

• is the physical appearance or characteristics seen in

an organism.

2Slide



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lesson question€¦ · slide instruction introduction to heredity heredity and genetics ... •...

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