Gregor Mendel

Lesson Overview

The Work of Gregor Mendel

THINK ABOUT IT

What is an inheritance?

It is something we each receive from our parents—a contribution that
determines our blood type, the color of our hair, and so much more.

What kind of inheritance makes a person’s face round or hair curly?

Lesson Overview

The Life of Gregor Mendel

The Life of Gregor Mendel

• Born in 1822 in Austria

• Wanted to be a teacher, but failed the exam (twice).

• Became a monk to have university paid for.

• Used pea plants to conduct his experiments at the monastery.

• Known as the Father of Genetics.

Multiple Choice

Why did Gregor Mendel become a monk?

• They had a good dental plan.

• They served very good food at the monastery.

• He was a deeply religious man.

• They offered to pay for university.

Lesson Overview

The Work of Gregor Mendel

The Experiments of Gregor Mendel

Where does an organism get its unique characteristics?

An individual’s characteristics are determined by factors that are passed
from one parental generation to the next.

Multiple Choice

Where does an organism get its unique characteristics?

• An individual’s characteristics are determined by factors that are passed down from the parents.

• An individual’s characteristics are determined by completely random factors.

• An individual’s characteristics are determined by factors that are passed down from the types of plants that are in your house.

• An individual’s characteristics are exactly the same as all other species.

Lesson Overview

The Work of Gregor Mendel

The Experiments of Gregor Mendel

Every living thing—plant or animal, microbe or human being—has a
set of characteristics inherited from its parent or parents.

The delivery of characteristics from parent to offspring is called
heredity.

The scientific study of heredity, known as genetics, is the key to
understanding what makes each organism unique.

Multiple Choice

The delivery of characteristics from parent to offspring is called

• exothermic

• Dominoes

• heredity

• trait

Lesson Overview

The Work of Gregor Mendel

The Experiments of Gregor Mendel

The modern science of genetics was
founded by an Austrian monk named
Gregor Mendel.

Mendel was in charge of the
monastery garden, where he was
able to do the work that changed
biology forever.

Multiple Choice

Who is Gregor Mendel

• an Austrian Monk from the mid 1800s who contributed to the study of Genetics

• The scientist who discovered the structure of DNA

• a British scientist who discovered penicillin

• The scientist who used X-Ray Crystallography to shed light on the structure of DNA

Lesson Overview

The Work of Gregor Mendel

The Experiments of Gregor Mendel

Mendel carried out his work with
ordinary garden peas, mostly because they grow quickly and have a lot of varieties. A single pea plant can
produce hundreds of offspring.

Today we call peas a “model
system.”

Multiple Choice

What did Gregor Mendel study?

• Mold Spores

• Pea Plants

• Sun Flowers

• Rats

Lesson Overview

The Work of Gregor Mendel

The Experiments of Gregor Mendel

Scientists use model systems
because they are convenient to study
and may tell us how other organisms,
including humans, actually function.

Lesson Overview

The Work of Gregor Mendel

The Experiments of Gregor Mendel

By using peas, Mendel was able to
carry out, in just one or two growing
seasons, experiments that would
have been impossible to do with
humans and that would have taken
decades—if not centuries—to do
with other large animals.

Multiple Choice

What specifically about Pea Plants did Mendel Study?

• Color of Pea Flower

• Colors of individual Peas

• Texture of Peas

• All of these

Lesson Overview

The Work of Gregor Mendel

The Role of Fertilization

Mendel knew that the male part of each flower makes pollen, which
contains sperm—the plant’s male reproductive cells.

Lesson Overview

The Work of Gregor Mendel

The Role of Fertilization

Similarly, Mendel knew that the female portion of each flower produces
reproductive cells called eggs.

Multiple Choice

What is the name of the female part of the flowering plant?

• plant ear

• little toe

• stigma

• ovule

Multiple Choice

What is the name of the male part of the flowering plant?

• plant ear

• little toe

• stigma

• ovule

Lesson Overview

The Work of Gregor Mendel

Genes and Alleles

From these results, Mendel drew two conclusions. His first conclusion
formed the basis of our current understanding of inheritance.

An individual’s characteristics are determined by factors that are passed
from one parental generation to the next.

Scientists call the factors that are passed from parent to offspring genes.

Multiple Choice

G = green, g = yellow
The genotype for a yellow plant is...

• GG

• Gg

• gg

• all of the choices result in yellow

Lesson Overview

The Work of Gregor Mendel

The Role of Fertilization

To do this, he had to prevent self-pollination. He did so by cutting away the
pollen-bearing male parts of a flower and then dusting the pollen from a
different plant onto the female part of that flower, as shown in the figure.

Lesson Overview

The Work of Gregor Mendel

Genes and Alleles

Each of the traits Mendel studied was controlled by one gene that occurred
in two contrasting varieties.

These gene variations produced different expressions, or forms, of each
trait.

The different forms of a gene are called alleles.

Multiple Choice

Genotype refers to the ...

• physical expression of the genes

• the possible combination of alleles in a gene

• whether an allele is dominant or recessive

• how an organism will appear

Lesson Overview

The Work of Gregor Mendel

Dominant and Recessive Traits

Mendel’s second conclusion is called the principle of dominance. This
principle states that some alleles are dominant and others are recessive.

An organism with at least one dominant allele for a particular form of a trait
will exhibit that form of the trait.

An organism with a recessive allele for a particular form of a trait will exhibit
that form only when the dominant allele for the trait is not present.

Punnett Squares

■

Step 1. State the key by using the capital letter of the dominant trait to
represent the dominant gene and the small letter of the dominant trait to
represent the recessive gene.
Ex: Y is used because Yellow is dominant to green, so a lowercase y is
used to represent green

■

Step 2. Write the cross using Homozygous and Heterozygous based
on information given to show the gametes. Ex: yy x Yy

■

Step 3. Draw the Punnett square and place the letters for the egg
alleles on one side of the square and the letters for the sperm alleles on
the other side of the square.

■

Step 4. Write the results inside each square by intersecting the
parents genes.

Multiple Choice

T - tall and t = short
In the punnett square below, what belongs in the missing square

• tt

• Tt

• Bb

• TT

Multiple Choice

B = brown fur  b = white fur
In the punnett square, what is the probability for white fur? 

• 0%

• 25%

• 50%

• 75%

Try This Punnett Square

In roses, red is dominant over white.

1. What letter represents the red
gene?

2. What letter represents the white
gene?

3. Cross two heterozygous red
roses. Describe the phenotype
of the offspring.

Multiple Choice

In a punnet square where are the parent alleles written?

• Top and inside the boxes

• Only on the left and right side of the boxes. 

• outside of the boxes (top and left side)

• All on the top side of the boxes

Multiple Choice

What is a punnett square?

• graph used to predict the possible genotypes of offspring in a given cross

• a graph used to predict the possible birth rate of offspring.

• a graph used to predict the possible behavioral characteristics an offspring could have

• None of the above

Multiple Choice

Two brown eyed parents (Bb) have a baby. What is the chance the baby is blue eyed?

• 0 %

• 25%

• 50%

• 75%

Multiple Choice

Heterozygous is when...

• the alleles are the same

• the alleles are different

• the alleles are absent

• the alleles are present

Multiple Choice

In a heterozygous genotype, the ___________ allele takes over in the phenotype.

• recessive

• dominant

• lower case letter

• both 

Multiple Choice

Which of the following alleles is homozygous (purebred) recessive?

• Tt

• tt

• TT

• t

Multiple Choice

Dominant alleles are represented by a:

• Male gene

• lowercase letter

• recessive trait

• capital letter

Multiple Choice

Aa, DD, bB, yy are all examples of

• genotypes

• phenotypes

Multiple Choice

In a heterozygous genotype, the ___________ allele takes over in the phenotype.

• recessive

• dominant

• lower case letter

• both 

Multiple Choice

What you see, or the physical appearance.

• Genotype

• Phenotype

• Homozygous

• Heterozygous

Multiple Choice

AA and Aa always show up as

• dominant

• recessive

Multiple Choice

aa always shows up as

• dominant

• recessive

Multiple Choice

Aa is

• homozygous

• heterozygous

Multiple Choice

Which of the following is a phenotype?

• Aa

• red hair

• heterozygous

• DNA

Multiple Choice

What is the dominant trait?

• yellow pea seeds

• green pea seeds

• there is no dominant seed

• Jolly green giant