Fun facts and background
information about common traits
used in this module.
S
pecial Features
You’ll Find Inside
Module
The Basics and Beyond:
An Introduction to Heredity
Inherited Human Traits: A Quick Reference
© 2006 University of Utah
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Background information for
educators.
Information about genes, traits, and inheritance that
supports student activities in this module.
Includes
a pictorial reference of inherited human traits used
in the module’s activities, along with inheritance
patterns, frequencies, and other interesting facts
about each.
A
bstract
L
earning Objectives
Visit the Learn.Genetics website to get links to
great resources like this one! Just login as a teacher,
and click on
The Basics and Beyond: An Introduction
to Heredity
to download engaging student activities
about inherited human traits.
A
dditional Resources
Background Information
Physical traits are observable characteristics determined by specific segments of DNA called genes. Multiple
genes are grouped together to form chromosomes, which reside in the nucleus of the cell. Every cell (except
eggs and sperm) in an individual’s body contains two copies of each gene. This is due to the fact that both
mother and father contribute a copy at the time of conception. This original genetic material is copied each time
a cell divides so that all cells contain the same DNA. Genes store the information needed for the cell to assemble
proteins, which eventually yield specific physical traits.
Most genes have two or more variations, called alleles. For example,
the gene for hairline shape has two alleles – widow’s peak or straight.
An individual may inherit two identical or two different alleles from
their parents. When two different alleles are present they interact
in specific ways. For the traits included in this activity, the alleles
interact in what is called a dominant or a recessive manner. The
traits due to dominant alleles are always observed, even when a
recessive allele is present. Traits due to recessive alleles are only
observed when two recessive alleles are present. For example, the
allele for widow’s peak is dominant and the allele for straight hairline
is recessive.
If an individual inherits:
•
Two widow’s peak alleles (both dominant), their hairline will have a peak
•
One widow’s peak allele (dominant) and one straight hairline allele (recessive), they will have a widow’s peak
•
Two straight hairline alleles (recessive), their hairline will be straight.
