Transcript 11.1 Intro Evo and Mutations

Mutations

November 1+1, 2009
Objectives:
By
the end of today, you will be able to
define a mutation and explain how they
contribute to variation.

Catalyst:
When
you hear the word mutation, what
do you think of? Write at least three
complete sentences.
Agenda





Catalyst Review
Mutations
Variations
Independent Practice
Exit Question
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. They
can be good, bad, or not matter at all.

Example:
 The
gene for making insulin (a protein that regulates
your blood sugar), could have the DNA sequence of
GTA-CGT-ACC-GTA-ACT…
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:
GTA-CGT-ACC-GTA-ACT

 Makes
mRNA: CAU-GCA-UGG-CAU-UGA
 Make
amino acid sequence:
Histidine-Alanine-Tryptophan-Histidine-STOP

This makes the protein which can reliably allow your
body cells to take in more sugar or release sugar in
order to maintain a good blood sugar level.
Messed Up Protein 1

Mutated DNA sequence 1: (switching
one base)
C-ACT
CAU-GCA-UGG-CAG-UGA  RNA!
GTA-CGT-ACC-GT
Makes
amino acid sequence:
Histidine-Alanine-TryptophanGlutamine-STOP
Messed Up Protein 2

Another mutated DNA sequence:
(switching one base that makes a
STOP codon)
T-GTC-ACT
CAU-GCA-UGA-CAG-UGA
GTA-CGT-AC
Makes
amino acid sequence:
Histidine-Alanine-STOP
Messed Up Protein 3

Even more mutated DNA sequence:
(insertions)
ACGTAACT
GTACGTAC
GTA-CGT-ACA-CGT-AAC-T
CAU-GCA-UGU-GCA-UUG-A
Makes
 RNA!
amino acid sequence:
Histidine-Alanine-Cysteine-AlanineLeucine
Mutations

Key Point #2
 Mutations
occur randomly in the DNA of
living organisms and this causes variation.
 They cause traits to be slightly different
from each other.
 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
Fitness: ability of an organism to pass
 What do you think fitness means?
its genes
on
to
the
next
generation.
 Amount of muscles?

NO!
 Heart

NO!
 How

rate?
many kids you have?
YESSSS!!!!!
Practice!




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




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




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?