Transcript 6.1 Mutation

Mutations

March 42, 2009
Catalyst:
When
you hear the word mutation, what
do you think of? Write at least three
complete sentences.
Write in complete sentences!
Don’t talk during the Catalyst!
Objectives
By the end of today, all SWBAT…
 Define a mutation
 Explain how mutations contribute
to variation.
Alright: New Unit!!! Evolution

We are beginning a two-week unit about evolution.
We are going to learn some things such as:
 Why
do some people have lighter skin and other have
darker skin?
 Why would a cuckoo bird lay her eggs in another
birds’ nest?
 Why did white moths become less common and gray
moths become more common near a factory?

The answer can all be found in evolution!
Introduction/Bridge



Evolution is DIRECTLY related to genetics.
The traits of all living things are found in their
DNA/chromosomes.
Why are there differences between people? Why
are there any differences among the individuals of
any living thing?
Mutations

Key Point #1
A
mutation is a change in the sequence of
DNA.

Example:
 The
gene for making insulin (a protein that
regulates your blood sugar), could have the
DNA sequence of GTA-CGT-ACC-GTAACT…
Figure it out yourself! (10 mins)



You need your codon tables from the
genetics unit
First, circle the difference in each mutation
from the original
After you finish, answer the question…
 Which
mutation would cause the biggest
change?
Why does that matter?



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Your DNA has instructions
to make the proteins!!!!
Changes in your DNA are
copied into your RNA.
That faulty RNA is used to
pick the amino acids in
your protein.
What could possibly
happen if you have the
wrong amino acids????
DNA
RNA
Protein
Correct Protein 1

Original correct DNA sequence:
A-ACT
CAU-GCA-UGG-CAU-UGA
GTA-CGT-ACC-GT
Histidine-Alanine-Tryptophan-
Histidine-STOP
Messed Up Protein 1

Mutated (switching one base):
C-ACT
CAU-GCA-UGG-CAG-UGA
GTA-CGT-ACC-GT
Histidine-Alanine-Tryptophan-
Glutamine-STOP
Messed Up Protein 2

Mutation (switching one base)
T-GTC-ACT
CAU-GCA-UGA-CAG-UGA
GTA-CGT-AC
Makes
amino acid sequence:
Histidine-Alanine-STOP
Messed Up Protein 3

Mutation (inserting a base):
A-CGT-AAC-T
GTA-CGT-AC
GTA-CGT-ACA-CGT-AAC-T
CAU-GCA-UGU-GCA-UUG-A
Histidine-Alanine-Cysteine-Alanine-
Leucine
What CAUSES mutations?

Radiation
 Radioactive
materials
 UV radiation

Old age
Mutations

Key Point #2
 Mutations
occur randomly in the DNA of
living organisms. This causes variation.
 Variation
is the differences among individual
phenotypes.

Example:
 Eye
color in humans.
More Variation Examples

Quickness in gazelles.

Leaf Size for a tea plant
It’s all about the babies

Key Point #3
 Mutations
can either increase fitness, decrease
fitness, or not change fitness
 What do you think fitness means?
Fitness:
ability
of
an
organism
to
pass
 Amount of muscles?
 NO! on to the next generation.
its genes
 Heart

rate?
NO!
Practice!

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There is a mutation that causes fur color in bears to become white.
When would this increase fitness and why?
 In snowy areas, this would increase fitness because these bears
would be able to hide easier. They could catch more prey, live
longer, and reproduce more.
When would this decrease fitness and why?
 In darker areas (such as the forest), this would decrease fitness
because these bears would stand out. They would not be able to
live as long and then they would reproduce less.
When would this not change fitness?
 If the bear was in an area where it did not need to hide, it may not
change fitness. This would change how much they reproduce.
Practice

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There is a mutation that causes rabbits to have
longer ears.
When would this increase fitness?
When would this decrease fitness?
When would this not change fitness?
Practice

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There is a mutation that causes trees to grow
shorter.
When would this increase fitness?
When would this decrease fitness?
When would this not change fitness?
Exit Question
What
is a mutation?
How do mutations contribute to
variation?
Write in complete sentences!
Don’t talk during the Exit Question!