Transcript 6.1 Mutation

Mutations

November 2, 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?




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
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 =
doability
you think
means? to pass
Fitness
of fitness
an organism
Amount
of
muscles?
its genes on to the next generation.
 NO!
How
many
children
it
has.
Heart rate?
 NO!
Practice!


There is a mutation that causes fur color in bears to
become white.
What is the relationship between this mutation and
variation in bears?
 Mutation



increases variation!
When would this increase fitness and why?
 In snowy areas  better at hunting
When would this decrease fitness and why?
 In dark areas (like the forest)  prey would see it
coming  would starve
When would this not change fitness?
 If it doesn’t need to hide to catch food
Practice




There is a mutation that causes eagles to have
larger claws.
What is the relationship between this mutation and
variation in eagles?
When would this increase fitness and why?
When would this not change fitness and why?
Practice




There is a mutation that causes grass to be black.
What is the relationship between this mutation and
variation in grass?
When would this increase fitness and why?
When would this decrease fitness and why?
Practice




There is a mutation that causes rabbits to have
longer ears.
What is the relationship between this mutation and
variation in rabbits?
When would this decrease fitness and why?
When would this not change fitness and why?
Practice




There is a mutation that causes trees to grow
shorter.
What is the relationship between this mutation and
variation in trees?
When would this increase fitness and why?
When would this decrease fitness and why?
Key Point Wrap-Up

Key Point #1
A

mutation is a change in the sequence of DNA.
Key Point #2
 Mutations
occur randomly in the DNA of living
organisms. This causes variation.
 Variation
is the differences among individual
phenotypes.

Key Point #3
 Mutations
can either increase fitness, decrease
fitness, or not change fitness
Exit Question
What
is a mutation?
What is the relationship
between mutations and
variation?
Write in complete sentences!
Don’t talk during the Exit Question!