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03-01 SG Genetics
LS.12
The student will investigate and understand that organisms reproduce and transmit genetic
information to new generations. Key concepts include
a) the structure and role of DNA;
b) the function of genes and chromosomes;
c) genotypes and phenotypes;
d) characteristics that can and cannot be inherited;
e) genetic engineering and its applications; and
f) historical contributions and significance of discoveries related to genetics.
Objectives: After this lesson, students will be able to
 Describe the results of Mendel’s experiments
 Identify what controls the inheritance of traits in organisms
Some of the students in class have brown eyes, some have blue eyes. Some have brown hair, red hair or blond hair.
Some of the students are tall while others are short. Each person has a special group of characteristics that make him or
her unique. These physical characteristics are called traits. Traits are passed or inherited from your parents. The
passing of traits from parents to offspring is called heredity. The scientific study of traits is genetics.
What is a trait?
What is heredity?
What is genetics?
Something you get from your parent.
The passing of traits to and off spring
The scientific study of traits
How did you get the traits or physical characteristics you have?
The first person to study heredity was an Austrian monk named
Gregor Mendel. He noticed that peas growing in the garden had a
variety of characteristics. Some of them were tall while others were
short. Some of the peas had round seeds, but others had wrinkled
seeds. Mendel studied seven of these characteristics. Mendel
studied peas because they were easy to grow and because they
have many traits that exist only in two forms.
He started his experiments with purebred plants. A purebred plant is one that always
produces offspring with the same form of a trait as the parent. Because of the results of his
experiments, Mendel concluded that traits were decided by two factors which exist in pairs.
Each parent gives one factor to each offspring. Today, scientists call the factors that
control traits genes. The different forms of a gene are called alleles. Individual alleles
control the inheritance of traits. Some alleles are dominant, while other alleles are
recessive. A dominant allele is one whose trait always shows up in the organism when
the allele is present. A recessive allele is masked, or covered up whenever the dominant
allele is present. A trait controlled by a recessive allele will only show up if the organism
does not have the dominant allele. A hybrid, is a combination or mix of both a dominant
and a recessive gene.
Mendel studied seven
different traits in pea
plants. Each trait has two
different forms.
Science Lives in Mr. Blackwell’s Room 119
©information from Prentice Hall Science Explorer Life Science
Page 1
First and last name ____________________________________
03-01 SG Genetics
Who was Gregor Mendel and what did he do?
Gregor Mendal was the first one to study heredity.
How many characteristics did Mendel study in peas?
Seven different characteristics.
Why did Mendel study peas?
Because they are easy to grow and have many traits.
What does purebred mean?
Purebred is a plant that only gets traits from its parents.
What are genes?
Factors that control personality.
What is dominant?
A dominant allele is one whose trait is always in the new organisum
What is recessive?
A recessive allele is masked or covered up when the dominant allele is present
What are alleles?
What is a hybrid?
The different forms of genes
A hybrid is a combination or mix of both a dominant and a
recessive gene
Science Lives in Mr. Blackwell’s Room 119
©information from Prentice Hall Science Explorer Life Science
Page 2