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Catalyst
1.
2.
3.
4.
5.
What are chromosomes composed of?
What are genes?
What forms the “rungs” of the DNA ladder?
Why is the sequence of bases important?
How are nitrogen base of DNA like the letters
of the alphabet?
Catalyst
1.
Why is the order of base pairs
important? Be specific-- (What
exactly happens if the order is
wrong—be sure to mention proteins,
and the genetic code).
I CAN…

I CAN describe why the order of
base pairs is important.
Mutation

A mutation is any change in a gene or
chromosome.
Mutations
Mutations can cause a cell to produce
an incorrect protein.
 As a result, the organism’s trait, or
phenotype, may be different from
what it would have normally been.
 Think of Hayden’s case…what
happened when that protein was built
incorrectly?

Mutations
InheritingInheriting
Mutations
MUTATION
In body cell...
In sex cell...
Will NOT pass to offspring!
WILL PASS to offspring!
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Types of Mutations
Type of Mutation
DNA Replication goes wrong...
Meiosis goes wrong...
Mutation at the DNA BASE LEVEL
Mutation at the CHROMOSOME Level
DNA bases out of order
Too many or too little chromosomes.
Ex. Tay Sachs disease
Ex. Down Syndrome

Mutations can occur both at the DNA
base level and at the chromosome
level.
Effects of Mutations
A mutation is harmful to an organism
if it reduces an organism’s chance for
survival.
 Reflect: When might a mutation be
helpful?

Genetic Disorder

A genetic disorder is an abnormal
condition that a person inherits
through genes or chromosomes.
Common Genetic Disorders
Cystic Fibrosis
 Sickle-Cell Disease
 Hemophilia
 Down Syndrome

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Exit Quiz

Why is the order of base pairs
important? Be specific (What exactly
happens if the order is wrong—be
sure to mention proteins, and the
genetic code).
Catalyst
1.
Why is the order of base pairs
important? Be specific-- (What
exactly happens if the order is
wrong—be sure to mention proteins,
and the genetic code).
Quick Write
1.
2.
Look around the room at the posted pictures.
How many different skin colors do you see?
What do you believe is happening at a genetic
level to produce the variety of skin color we see
in the human species? Use your new
understanding of genes and alleles to make an
educated guess.
Patterns of Human
Inheritance
The inheritance of traits is rarely as
simple as in Mendel’s experiments.
 Human traits rarely come in just two
simple forms like pea plant flowers.

3 Patterns of Human
Inheritance
1.
2.
3.
Trait controlled by single gene with
2 alleles.
Trait controlled by single gene with
multiple alleles.
Trait controlled by many genes that
act together.
Single Gene with 2 Alleles
Traits that are controlled
by a single gene with just
two alleles only have two
possible phenotypes or
physical appearances.
 Examples: Widow’s Peak
or No Widow’s Peak

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Single Gene with Multiple
Alleles
Multiple alleles: three or more forms
of a gene that code for a single trait.
 Example: A gene that comes in three
forms: purple, white, and blue.

Single Gene with Multiple
Alleles



Even though a gene may
have multiple alleles, a
person can ONLY carry 2
of those alleles because
chromosomes exist in
PAIRS (not triples,
quadruples etc.)
Each chromosome in a pair
only carries one allele for
the trait.
Example: Human Blood
Type
– A, B, AB, or O.
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Traits Controlled By Many
Genes
Some human traits
show a large variety of
phenotypes because
the traits are
controlled by many
genes.
 The genes act
together as a group to
produce a single trait.
 Example: Height, skin

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Q: Why do some traits show
so much variation?
Gummy Bear Breeding Part 2
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Gummy Bear Notes Reading
Introduction to GB
Breeding…
In gummy bears, fur color is actually
controlled by TWO genes, each one
with two possible alleles.
 For example, bears who have a
genotype of CC AA for fur color will
have a phenotype of green fur color.
 The next table reveals the remaining
possible combinations of fur color
alleles and the revealed phenotype
(the fur color we see!)

Introduction continued…

Copy the table below into your notes…
Genotype
CC AA
CC AB
CD AA
CD AB
DD AA
DD AB
Phenotype
Green
Clear
Red
Orange
Yellow
Purple
Question 1
1.
What type of inheritance pattern do
these gummy bears show?

Multiple genes with only 2
alleles each.
Your task…

Your job in this activity, is to predict
(before looking in the brown paper
bag) all of the possible genotypes and
phenotypes of the baby gummy bears
produced in a cross between two
parent gummy bears.
Question 2 and 3
The genotypes of the proud gummy bear
parents are labeled on the outside of your
bag.
2. What are the genotypes of your
expecting gummy bear parents?

XX AA
A. Mother Genotype: _____
_____
YY AA
B. Father Genotype: _____
_____
3.
What are the phenotypes of each parent?
A. Mother Phenotype: _____ _____
B. Father Phenotype: _____ _____
Question 4
4.
Remember that meiosis creates egg and
sperm cells (the sex cells), and that each
sex cell has only one allele from each
parent for each gene. Given this
information, list the possible alleles for
each sperm or egg cell.
A. Egg Options:
B. Sperm Options:
Question 5 and 6
What are all of the possible genotypes
for the next gummy bear generation.
(Hint: mix the sex cells you created above
around to find all possible combinations)
6. What will be the phenotypes for the
combinations above in Question 5? Use
your chart.
5.
Question 7

Open the brown paper bag with the
next gummy bear generation in it.
Were your predictions correct? What
are the phenotypes you see inside?
Question 8
8.
Were the offsprings’ phenotypes
the same or different from the
parents’? Were you surprised by the
results: why or why not?
Question 9

In gummy bears there were only two
genes that determined fur color. In
humans, there are over 100 genes
that contribute to skin color. Explain
how this will result in the HUGE
variation we see in human skin color.
Exit Quiz
What are two types of mutations?
 What are the three patterns of
inheritance in humans?
