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Introduction
Heredity is the passing on of traits, or characteristics, from parent to
offspring. The units of heredity are called genes. Genes are found on the
chromosomes in the cell. The combinations of genes for each trait occurs
by chance.
When one gene in a gene pair is stronger than the other gene, the trait
of the second gene is the recessive gene. Dominant genes are written as
capital letters and recessive genes are written as lowercase letters. If
both genes in a gene pair are the same, the trait is said to be pure. if
the genes are not similar, the trait is said to be hybrid. Sometimes genes
can be neither dominant or recessive. The result of such a situation is
incomplete.
The genetic makepu of an individual is known as its genotype. The observable
physical characteristics of an individual that are based on its genotype
ar known as its phenotype. In humans, the sex of an individual is determined
by the male gene. Individuals who have two X chromsomes (XX) are females,
whereas individuals with an X and a Y chromosome (XY) are males.
Subject: Science
Topic: Heredity/Genetics
Grade Level: 7th
Student Lesson name
and URL:
Standards
Addressed
Science: Focus on
Life Science
Genetics
1. A typical cell of any organism
contains genetic instructions that specify its traits. Those traits may
be modified by environmental influences. As a basis for understanding this
concept, students know:
a. the differences
between the life cycles and reproduction of sexual and asexual
organisms.
b. sexual reproduction
produces offspring that inherit half their genes from each
parent.
c. an inherited
trait can be determined by one or more genes.
d. plant and
animal cells contain many thousands of different genes, and typically
have two copies of every gene. The two copies (or alleles) of the gene
may or
may not be identical, and one may be dominant in determining the phenotype
while the other is recessive.
e. DNA is the
genetic material of living organisms, and is located in the
chromosomes of each cell.
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Instructional
Objectives
Insert your learning objectives
here. For example:
-
After viewing an animation of
continental movement on a laser disk, students will be able to arrange
the fit of the continents with continental puzzle pieces.
-
After analyzing information from
an Encarta CD, students will be able to compare the distribution of fossils,
rock types and ancient climatic zones on different continents as evidence
for plate tectonics by fitting puzzle pieces marked by these special features.
-
Students will be able to draw
a diagram of the earth's layers.
-
After collecting information from
The Earth CD, students will be able to locate earthquakes, volcanoes and
mid ocean ridges as evidence for plate tectonics.
-
After viewing a laser disc geology
chapter, students will be able to pass a true/false quiz on lithospheric
plates and layers of the earth.
-
Students will be able to identify
the major geologic events that result from plate motions in a Power Point
multimedia presentation.
-
Students will be able to present
their findings on the sixth grade plate tectonics and Earth's structure
standards in a Power Point multimedia presentation to an audience of peers
and adults, including the World Geologic Society.
-
Students will be able to write,
edit and revise their findings on the sixth grade plate tectonics and Earth's
structure standards using correct grammar, spelling and punctuation.
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Student
Activities
Insert brief summaries of
your introductory, enabling, and culminating activities. Insert links to
online resources in your text and insert links to activities on your student
lesson web site.
Introductory
Activity: Observing Human Traits
Background Information
Human
Human traits, like those of other organisms, are inderited. In human beings,
you see dominant, recessive and sex-linked traits. For example, tongue
rolliing is a simple dominant trait. A person who has the trait can roll
his orher toungue into the shape of a U. Another dominant trait is free,
or unattached, ear lobs. Red-green colorblindness is a sex-linked recessive
trait in humans. A person with this trait cannot easily distinguish the
color red from the color green.
In
the study of human genetics, scientists examine pedigrees, or family records,
that show the transmission of inherited traits. Studying a petigree may
enable a scientist to determine a person's genotype with respect to the
traits studied.
In
this investigation you will determine the possible genotypes and phenotypes
of certain crosses. You will also construct your own pedigree.
Problem:
How
can human traits be studied? How is a pedigree constructed?
Materials:
Procedure:
1.
Using figure 3 of Observations, complete the Punnett square for
the possible offspring of a woman who has a dominant and recessive gene
for tongue rolling and a man who cannot roll his tongue.. Let T = gene
for tongue rolling the t = gene for inability to roll the tongue.
2.
In a pedigree, circles represent females and squares represent males. If
either shape completely colored in, it means that the person has the trait
being studied. Horizontal lines are used to connect the parents, and the
children are shown by vertical lines. The known genotypes for each
person may be written below each circle or square. The female chromosomes
are XX, while the male chromosomes. are XY.
3.
Figure 1 represents the pedigree for colorblindness. Let C = gene for normal
vision and c = gene for colorblindness. If a female is colorblindness
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Enabling
Activity(ies)
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Culminating
Activity
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Assessment
Insert your grading rubric
for the culminating activity or a link to your rubric or test document
file.
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Results
After implementing your lesson
(sometime between January & March), insert a chart of your pre-test,
post-test, and culminating assessment data.
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Web
Resources & Supplementary Materials
Introductory Activity
List and link the web resources
for this activity here. Also link supplementary materials such as PDF files
and /or document files.
Enabling Activity
List and link the web resources
for your learning activity(ies) here. Also link supplementary materials
such as PDF files and /or document files.
Culminating Activity
List and link the web resources
for your culminating activity here. Also link supplementary materials such
as PDF files and /or document files.
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Anderson
Middle School
Anderson,
California
E-mail
me at: ncunnion@shastalink.k12.ca.us
Last Revised:
December, 2000 |