base substitution and frameshift mutations

1. 1-24-17 Warm up
Write the
DNA for the
amino acid
sequence:
Met-Trp-Pro-Gly

2. Plans for the week
• Monday – research a
geneticist
• Tuesday – share your
brochure; mutations
lesson
• Wednesday – mutations
lesson
• Thursday – review
molecular genetics
• Friday – molecular
genetics exam
• DNA structure and function
• Cell specialization and gene
expression
• Chromosome structure
• Karyotypes
• DNA replication
• formation of mRNA
• Using a codon chart
• role of mRNA, tRNA, and
ribosomes (rRNA) in the
production of proteins
• Mutations types
• Some important work by
some important scientists

3. 1-24-17 Agenda
1. Warm up
2. Mutations lesson until 11:30; 1:10; 2:15
3. Time to work on Brochure (last class time)
1. To have me print you must format to be 1
page back-to-back

4. Objective
 Students will analyze point mutations and
explain how the mutation affects the
sequence of amino acids.

5. Mutations

6. What you know so far…
 DNA codes for ________
 Proteins are made up of
_____ ____
 We can determine the
order of the ___________
in a ______ by using a
codon chart.
proteins
amino acids
amino acids
protein

7. How this connects to our new
lesson
 Proteins must
have exactly the
right shape to
work properly
Normal
protein
shape
Abnormal
protein shape
due to wrong
amino acids

8.  A mutation is a change in the genetic
code that causes the protein that is
coded for to have the wrong shape or
not be made by the cell

9. What kinds of mutations are
there? Bo Xishun 7’9”
Chandra Bahadur Dangi
21.5”

10. Point Mutations
 Changes in one or a few of the nitrogen
bases (letters) of the DNA code
– There are 2 main types

11. 1. Base substitution = a letter (or a
few letters) is substituted for another
How could
such a small
change make
a difference?
A change in the
bases might lead
to a change in
the amino acid
coded for

12. Add this diagram to your notes
Substitution of
bases (letters) Different
amino
acid
Wrong
protein
shape
Same
amino
acid
Same
protein
shape
No effect
on
person
Disease
or
disorder
Example:
Example:

13. Base Substitution Mutation
 Think of it like a sentence:
 Normal sentence would read
– THE DOG BIT THE CAT
 A base substitution mutation might make
the sentence read:
– THE DOC BIT THE CAT
This changes the meaning of the sentence

14.  Changing a single base
can cause a dramatic
change:
– Example: sickle cell anemia

15. Practice
Normal DNA: TAC GGC TTT
Mutated DNA: TAC GGC GTT
Step 1: Circle any mutations
Step 2: Transcribe DNA to mRNA
Step 3: Group mRNA into codons
Step 4: Use the codon chart to list the amino
acids
Q1: Where is the
mutation in this
DNA strand?
Q2: What amino
acid was
changed?
Q3: What kind of
mutation is this?

16. Practice
Normal DNA: CAA ACC GGG
Mutated DNA: CAA ACT GGG
Step 1: Circle any mutations
Step 2: Transcribe DNA to mRNA
Step 3: Group mRNA into codons
Step 4: Use the codon chart to list the amino acids
Q1: Where is the
mutation in this
DNA strand? Q2: What amino
acid was
changed?
Q3: What kind of
mutation is this?
Q4: How would
the protein
product be
affected?

17. Not all mutations cause problems
 Viable mutations – mutations that do
not decrease the ability of an organism
to survive and reproduce


18.  Changing a single
base may not cause
any change at all:
– Proline is coded for
by GGG, GGA, GGC,
and GGT
List at least two amino acids that
are coded for by 2 or more
codons. Write the names of the
amino acids and all their codons
on your whiteboard.
Are any amino acids
coded for by only 1
codon?
What are they?
We call these
SILENT
mutations

19. Add this to your diagram
Substitution of
bases (letters) Different
amino
acid
Wrong
protein
shape
Same
amino
acid
Same
protein
shape
No effect
on
person
Disease
or
disorder
Example:
Example:https://www.youtube.com/watch
?v=o3yQZp5Rs-o

20. Practice
 Partner A:
Normal DNA:
GAC AAG TCC
Mutated DNA:
GAC TAG TCC
 Partner B:
Normal DNA:
TCC ACA CTG
Mutated DNA:
GCC ACA CTG
Complete the sentence. Share with your partner and then
share with the class.
What kind of mutation is it?
Will it affect the protein? Explain.

21.  2. Frameshift
mutation =
the addition
or deletion of
1 or a few
base pairs

22. Frameshift Mutation
 Think of it as a sentence again:
– THE DOG BIT THE CAT
 Adding an extra letter makes it:
– THH EDO GBI TTH ECA T
 It changes the entire sentence to nonsense.
This kind of mutation always has a negative
effect on the protein product.

23.  Some diseases caused by frameshift
mutations:
 Breast cancer
 Cystic fibrosis
http://www.pbs.org/wgbh/nova/g
enome/program_t.html

24. More practice
 Partner A:
Original DNA:
GGGTTTACC
Mutated DNA
GGGATTTACC
 Partner B:
Original DNA:
GGGTTTACC
Mutated DNA
GGTTTACC
Q1. What kind of
mutation is this?
Q2. How would
this mutation
affect the protein
product?

25. More practice
 Write a DNA sequence of 9 letters.
 Label it “Original DNA”
 Then write the same DNA sequence but
with one of the mutation types we are
learning about.
 Give it to your neighbor to solve.
 Complete this sentence using the
problem your neighbor gave you.
This is an example of a ________ mutation. I can tell
because _________. This mutation will/will not change
the protein because _________________.

26. Now try it on your own
 Complete the three practice problems
on the worksheet.
 Have your teacher check it when you
are finished.