Transcript Mutations - Miss Garry`s Biology Class Website!

Mutations!
When things go wrong in the DNA!
Objective (YOUR GOAL
BY THE END OF THE
CLASS PERIOD!):
I will be able to identify
mutations in a DNA
sequence
Mutated Frog
What is a Mutation?
 Mutations = a permanent change in the DNA
sequence
- A base (letter) in the DNA is changed
What is the effect of a mutation?
 Mutations are a natural process that can lead to:
a. No effect  nothing happens to the
phenotype
b. Beneficial effect  phenotype is affected.
The organism is better adapted to its
environment
c. Harmful effect  phenotype is different.
The organism is less adapted to it
environment
How do mutations affect
proteins?
 Proteins have to be folded a certain way to
work
 Mutations can change the type of amino acids
in the polypeptide
 This can change how the protein folds = may no
longer work
What causes mutations?
 Mutagens: Environmental factors
such as UV light, x-rays,
cigarette smoke, etc.
 As DNA replicates, sometimes mistakes can
occur
Mutations in DNA may cause cancer


Cancer: uncontrolled cell growth
Mutations may change the proteins that help
control how fast cells divide

Result: cells divide too quickly
leading to cancerous tumors
Cancerous
Benign
CFU
1. Mutations within a DNA sequence are:
A Natural process that always affect the
phenotype
B Natural process that produce genetic
diversity
C Unnatural processes that always affect
the phenotype
D Unnatural processes that are harmful to
genetic diversity
Two types of gene mutations
1. Point (base substitution) mutations
2. Frameshift mutations
1. Point Mutation
• Substitution of a nucleotide
- One base is switched for a different base
normal
mutation
 Point Mutations can either have an effect or
have no effect
 Ex:
C–A–T–G–A–G
C–A–G–G–A–G
•Ex) UAU= tyrosine UGU= cytosine
•Ex) Sickle Cell Anemia
Sickle Cell Anemia
Shape of the protein hemoglobin
in your blood
GAA makes glutamic acid
In sickle cell anemia, GAA is
changed to GUA which makes
valine
Cystic Fibrosis
2. Frameshift Mutation

A.
Two types:
Insertion: an extra nucleotide (base) is added to the
sequence
•
B.
Example: ATCGTC  ATTCGTC
Deletion: A nucleotide (base) is missing
•
Example: ATCGTC  ACGTC
Deletion of U
What is the result of a frameshift mutation?
•
Causes the codons to shift and changes all the amino
acids following the mutation
Insertion Example
 Ex) The big fat cat The big sfa tca t
 Ex) C – A – T – G – A – G 
C–A–C–T–G–A–G
Deletion Example
 Ex) The big fat cat  Thb igf atc at
 Ex) C – A – T – G – A – G
C–A–T–A–G
Review: Difference between a point mutation
and a frameshift mutation.
 Which one do you think has a greater effect on the protein?
Why?
Checking for Understanding:
Original: THE DOG BIT THE CAT
Mutation: THE DOG BIT THE CAR
1. Point or frameshift?
Check for Understanding:
Original: THE DOG BIT THE CAT
Mutation: THE DOB ITT HEC AT
2. Point or frameshift? Insertion or deletion?
What types of mutations?
3.
4.
Frameshift:
Insertion
Frameshift:
Deletion
Catalyst
1. Identify the type of DNA mutation shown below:
AGCTTGCCA  AGCTTTGCCA
A
B
C
D
Insertion
Deletion
Substitution
Inversion
2. Which of the following would be most likely to cause a mutation:
A When endoplasmic reticulum is missing ribosomes
B When mRNA does not leave the nucleus the right way
C All of the nitrogen bases are in the right order
D A deletion of a nucleotide in DNA
3. What is the new door policy for my room?
Announcements
•
•
•
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Homework packet due Friday
Tutoring today after school today and Thursday
Extra credit for bringing in printer paper
Peer health
WEDNESDAY: Textbook Questions
Directions: Use Chapter 8.7 (pages 252-255) to answer the
following questions
.
THURSDAY: Multiple-Choice Questions
Directions: Write five multiple-choice questions that could be used on the quiz. Make
them creative and challenging. Each question should have four choices (a-d).
Question #1:
______________________________________________________________________
a) _______________________________________________________________
b) _______________________________________________________________
c) _______________________________________________________________
d) _______________________________________________________________
DO NOW
Please place your Tuesday HW of your desk 
Answer the following questions on the BACK of
the Spiderman worksheet
What is a mutation?
Are mutations natural or unnatural?
What are the different kinds of mutations we
learned about yesterday?
On your own, or with a partner, begin completeing
the front of the Spiderman Mutation worksheet!
Hint: Numbers 1-3 all occur near
the second A. Numbers 4-6 all
occur near the last G.
TAC GAT GGC
1. TAC GTG GC
deletion
2. TAC GGT GGC
substitution
3. TAG GAC TGG C
insertion
4. TAC GAT GAC
Substitution/ point mutation
5. TAC GAT GGT C
Insertion
6. TAC GAT GC
deletion
For Questions 7-9: the original DNA sequence is ATT ACC GAG. You will
create the examples of mutations that may occur in the DNA of a human
skin cell. Indicate the location of the mutation by underlining.
7. Give an example of a point mutation given the above sequence
ATT ACC GAC
8. Give an example of an insertion that may occur.
ATT TAC CGA G
9. Give an example of a deletion that may occur.
ATA CCG AG
Frameshift (insertion and deletion) and point mutation
Frameshift is more harmful.
•How does a mutation result in the change in the protein created?
•The amino acids are the changed resulting in the
protein to be different.
•Do you think most mutations are good or bad? Why?
•What causes mutations? What are some examples of mutagens?
•Mutagens: UV light, cigarette smoke,
•DNA replication mistakes, problem with the chromosomes,
genetics
•
•
DNA mutation video
Discovery Channel – Human Mutations
1. The following is a strand of DNA that a protein will be made
from. Write the “transcripted” mRNA in the spaces below it.
2. G
– A – C – G – C – C – A – T – G – G – A – A – G – T–C
3. __ - __ - __ - __ - __ - __ - __ - __ - __ - __ - __ - __ - __ - __ - __
4. Draw a line between each codon.
5. Look up the amino acid for each codon on the codon chart
and write them in the spaces below. Be sure to do this in
order. This is the “normal protein.”
6. ________ - ________ - _______ - ________ - ________
MUTATION ACTIVITY
Word Wall
mutation
tRNA
codon
Point mutation
anticodon
gene
Frame shift mutation
amino acid
Insertion
protein
Deletion
ribosome
Mutagen
transcription
Polypeptide
central dogma
Translation
RNA
Genetic Disorders
•
A genetic disorder is a disease that is caused by
an abnormality in an individual's DNA.
Abnormalities can range from a small mutation in
a single gene to the addition or subtraction of an
entire chromosome or set of chromosomes.