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Genetics
Grade 7
1
Heredity: The process in which
characteristics or traits pass from parents
to offspring.
Think, Pair, Share some characteristics
that you have in common with either
parent
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Tracking Down Traits
Learning Experience 1
1. Review Procedures
2. Rule: No person may sign the list more
than twice.
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Traits are Carried in Tiny Structures
Called Genes
Genes are Found in the Nucleus of Cells
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What Genes Do in Your Body
• Each cell in the human body contains about 25,000 to 35,000
genes,
that carry information to help determine your traits.
• Traits are characteristics you inherit from your parents;
• This means your parents pass some of their characteristics on
to you through genes
TPS: what does
the statement
“ You inherit
traits from your
parents” mean?
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Genes carry information that helps
make you who you are
Genes are made of DNA
A gene is a section of DNA that
controls a trait ( ex. tall /short) that an
organism inherits
TPS: if genes are sections
of DNA, where are genes
located in the cell?
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What do you know about
DNA?
Where have you
heard the term?
What was the context
or situation?
DNA
Write this in your
notebook and be
ready to share with
your class as your
teacher records on
the board.
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What is DNA?
• The genetic material that
carries information about an
organism passed from
parent to offspring
• A complete set of
instructions necessary to
make and maintain the
human body.
• A Blueprint of the human
body
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Why is DNA Interesting?
•
•
•
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DNA is a nonliving molecule.
There are 6 feet of it in every cell.
DNA is unique for every individual
DNA controls all the activities in the cell.
TPS: Why is DNA interesting?
TPS: What is DNA?
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DNA and Crime Solving
• Because DNA is a nonliving, nonreactive
chemical molecule…
• It can be recovered from mummies over
2000 years old.
• Long-dried blood in murder investigations
• Ancient bones
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Chromosomes
• DNA is too long to fit into a nucleus, it must be
tightly wound-up to fit inside the cell.
• Chromosomes are DNA wrapped around
proteins to form an X-shaped structure.
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Where is
DNA?
Found in Cells…
inside the
Nucleus , the
Control Center.
DNA is wound
tightly into
structures called
Chromosomes so
it can fit into a tiny
cell…
so,
Chromosomes are
made of DNA
Short sections of
DNA in the
chromosomes are
called Genes
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Where is DNA?
In your Notebook:
Draw and label the
location of DNA in
the cell
Draw and label the
relationship between
DNA, genes and
chromosomes.
Analogy:
DNA is like yarn that can be wound
Into a tight ball ( chromosome);
it can contain many colors (genes)
on the
same piece of yarn and can be used to
make something (traits)
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Each human Cell have 23 pairs of Chromosomes
Mother
Father
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A Model of a Chromosome
Gene
•Chromosomes are made up genes.
•A gene is a section of DNA (section
of a chromosome) that controls a
trait that an organism inherits.
•If the string of shapes represents a
chromosome – what does each
individual shape represent?
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Gene for the Trait
Brown Eye color
Gene for Tall Height
Gene for Brown
Hair color
Gene for the Shape of
our Fingers – long
and slender
Gene for Attached vs
Unattached Earlobes
TPS: how many genes are on
this chromosome model?
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Humans Chromosomes
TPS:
What are the dark
lines?
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How important are chromosomes?
• Humans need all 46
chromosomes for normal
development and function.
• Humans that are missing even
one of the 46 chromosomes do
not survive.
• Humans with more than two
copies of a chromosome will
not develop properly.
Downs Syndrome is caused
by an extra chromosome.
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Compared to a real human chromosome,
what are the limitations of the model?
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Active Learning
• Write a riddle about one or two of the
following terms:
– DNA, Genes, traits, chromosomes
• Write a Haiku about the importance of
DNA
(5-7-5 syllable pattern)
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1
2
3
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One set of chromosomes come from the
mother and one set of chromosomes come
from the father.
The entire chain of shapes represent a
chromosome - the individual shapes
represent genes.
The offspring inherits a pair of genes for
each trait. When the genes are identical
the offspring is called homozgous or
purebred for that trait. When the genes
are different, the offspring is called
heterozygous or hybrid for that trait.
Which gene pairs would make a
homozygous offspring ? (similarities)
Which genes pairs would make a
heterozygous? (Differences)
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2
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1
2
3
4
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Gene for the trait
Brown Eye color
Gene for Brown Eye
color
Gene for Tall Height
1
Gene for Tall Height
2
Gene for Brown
Hair color
Gene for the
Shape of your
Fingersslender
Gene for Attached
Earlobes
What is
the mother’s
phenotype
for each
trait?
Gene for Black
Hair color
3
Gene for the
Shape of your
Fingers-fat
Gene for Unattached
Earlobes
Phenotype-The physical characteristics/traits you can observe
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5
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1
2
3
4
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Gene for the trait
Brown Eye color
Gene for Tall Height
Gene for Brown Eye
color
1
Gene for Tall Height
2
Gene for Brown
Hair color
Gene for Black
Hair color
3
Gene for the Shape
of your Fingersslender
Gene for Attached
Earlobes
Gene for the
Shape of your
Fingers-fat
Gene for Unattached
Earlobes
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Genotype- The two genes that determine an organism's (offsprings) traits
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Do Your Earlobes Hang
Down?
Learning Experience 2
1.
2.
3.
After each trait is described – mark a
check under Yes or No in the Me column.
Collect data for each trait from the entire
class.
Graph class data for each trait
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Vocabulary
• Genotype – the two • Phenotype – The
genes that determine
physical characteristics
an organisms traits
of an organism you
can observe.
• The genotype of a tall
plant that has two
• The phenotype of a tall
genes alleles for
plant is tall, regardless
tallness is TT
of the genes it contains
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Transparent Traits
Learning Experience 3
This activity models the random selection of a egg and a sperm in
producing the genotype and phenotype of offspring.
Please model using the overhead prior to the students conducting the
lab.
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Transparent Traits
Formative Assessment Questions
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What do the colored squares represent?
Why are the genes always removed in pairs?
Where does the organism acquire its genes?
If two colored squares are drawn, what was the organism’s
genotype?
Is the trait dominant or recessive in this organism?
What was the phenotype of this organisms?
If two clear squares were drawn, what was the organism’s
genotype?
If one clear and one colored square are drawn, what was the
organism’s genotype?
Is the trait dominant or recessive in this organism?
What was the phenotype of this organism?
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Based on what you know about genetics thus
far…
What are the limitations of the model?
•Each square represents one gene on one
of the 23 chromosomes.
•Each gene is not selected individually –
they come in packets called ____?
•Human traits like eye color and hair color
have multiple alleles – they are the results
of one gene from the mother and one gene
from the dad.
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Putting it All Together
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Homozygous
Heterozygous
Phenotype
Genotype
Dominant
Recessive
• Dragon Genetics
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Processing
Using the dragon simulation as
an example:
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•
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What was changed in order to
change the appearance of the
dragon?
Therefore, a change in the ____
results in a change in the _____.
Do you have to change the genes
on both chromosomes to change
the phenotype? Explain
•
How is the phenotype affected by
the genes being homozygous or
heterozygous?
•
How many different dragon
combinations are possible?
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Mastering Terms
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Homozygous
Heterozygous
Phenotype
Genotype
Dominant
Recessive
• How can students
demonstrate their
understanding of
these terms?
Term
Def. in own
words
Picture
Example
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Gregor Mendel
Father of Genetics
• The Story of Gregor
Mendel
• Mendel’s
Experiments:
http://www.cccoe.net/
genetics/mendel.html
• Dominant and
Recessive Traits
http://www.cccoe.net/
genetics/dom_rec.htm
l
Activities:
• Interactive Guide to
Mendel’s Experiments
(7th)
• Some Traits are
DominantAnimation/Activity
• http://www.dnaftb.org/
dnaftb/4/concept/
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Write a radio commerical to advertise a visit to your school by
Gregor Mendel. The advertisement should include:
•Why his research impacts what we know about genetics.
•Something that would spark the interest of the students to
come to the presentation.
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Genes in Action
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• Reflect back on
Cody and Codette’s
offspring.
• Which organisms
would live to survive
and pass on their
genes in this
environment?
• Which would not?
• Which organisms
would be “naturally
selected” to survive
and which would
not?
Cody and Codette
• Reflect back on Cody and Codette’s
offspring. After the entire class has
completed their organism and placed them
into an environment.
• Which organisms would live to survive and
pass on their genes?
• Which would not?
Vocabulary
• Natural occurrence is Natural Selection
• Natural selection is the process by
which certain heritable traits—those
that make it more likely for an
organism to survive and successfully
reproduce —become more common
in a population over successive
generations.
Vocabulary
• Selective breeding:
• The method of breeding certain organisms
together that have desirable traits.
• The process of manipulating the
phenotype of the offspring.
Example of Selective Breeding
Hardy – can thrive in hot
climates, the beef is not as
good
Tender, tasty beef
Does not thrive in hot
climates
Heat resistant cattle with tender beef
Selective Breeding - Ancestry
American Bulldog
Bull Mastiff
Staffordshire Bull Terrier
American Pit Bull Terrier
Selective Breeding
Try it Out!
• Dog Breeding
Ethics
• Think Time
Discuss some possible positive outcomes of :
•Selective Breeding
•Cloning
•Genetic Engineering
Discuss some possible negative outcomes of:
•Selective Breeding
•Cloning
•Genetic Engineering
Putting It All Together
• Sponge Bob
• Make an Acrostic from the word “Heredity”
• Create analogies using the following pairs
of words:
– Homozygous/heterozygous
– Phenotype/genotype
– Dominant/recessive
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