Transcript File - Ms. Becerra`s Biology class

DNA Mutations
When our DNA has mistakes!
Copy everything in BLUE on Page
A DNA MUTATION is a change or mistake in the
DNA sequence that may or may not affect the
proteins.
G
3’
A
T
A
C
T
T
C
A
G
5’
Causes of DNA Mutations
1. Environmental Factors
(UV light, radiation,
chemicals, etc.)
2. Mistakes during DNA
replication – TRANSCRIPTION
MISTAKES DON’T COUNT!!
NOTE: DNA polymerase
makes about 1 mistake in
every 50 MILLION bases
during replication!!
3 Types of Mutations
1. Substitution (AKA Point Mutation):
Substitute = take
outdoes
something
and replace
it with another
What
substitute
mean?
Map of Malaria Cases
Map of Sickle Cell Cases
Substitution/Point Mutation:
when one or more DNA bases are replaced
G
A
T
A
G
C
T
T
C
A
3’
G
5’
Original
or Normal
Mutated
DNADNA
If you have a mutation in your DNA…
It could change your mRNA…
It could change the amino acid…
It could change the protein!
An English Example…
Normal:
THE MAN SAW THE DOG EAT THE RUG
Point Mutation:
THE MAN SAW THE FOG EAT THE RUG
Frameshift Mutations
2. Deletion Mutation:
when one
or=more
are deleted
What
delete
mean?
Delete
todoes
takeDNA
awaybases
something!
CYSTIC FIBROSIS
Normal CFTR Sequence:
G
3’
ANucleotide
T
Amino Acid
A A T CC A T CT
Ile -
T G GC
TTT
T G TA
T
Ile - Phe - Gly - Val
CFTR Sequence:
IfAbnormal
you have
a mutation in your DNA…
Nucleotide
A T C A Tyour
T GG
T GTT
It could change
mRNA…
Amino Acid
Ile - Ile - Gly - Val
It could change
the amino acid…
It could change the protein!
G
5’
Cystic Fibrosis
Healthy
Cystic Fibrosis
MUCUS
An English Example…
Normal:
THE MAN SAW THE DOG EAT THE RUG
Deletion Mutation:
THE MAN SAT HED OGE ATT HER UG
Frameshift Mutations
3. Insertion Mutation:
when
or something
more
bases
areobject
added
Insertone
=What
add
is doesDNA
insert
into
mean?
another
G
A
T
A
C G T
T
C
A
3’
G
5’
If you have a mutation in your DNA…
It could change your mRNA…
It could change the amino acid…
It could change the protein!
An English Example…
Normal:
THE MAN SAW THE DOG EAT THE RUG
Insertion Mutation:
THE MAN SAW THE FAT DOG EAT THE RUG
Effects of Mutations
Mutations can be…
1. Neutral (no effect)
2. Beneficial (good)
3. Harmful (bad)
Sickle
Cell
Anemia!
Cystic
Fibrosis!
NOTE: Most mutations
are neutral because it
usually does not affect
the amino acid.
Possible HIV cure??
Why are most DNA mutations neutral?
• There are many
possible codons
for the same
amino acid!
• Most likely the protein will
not be affected.
• DNA can also repair itself.
• A mistake may happen in a
“recipe” that the cell does
not use.
• A few mistakes is minor in
comparison to the 6 billion
bases you have!
Will mutations be passed on to their
children?
Only if the DNA mutation is in the testes or
ovaries (sex cells)!
A mutation in any other
cell only affects parent.
We will talk about
chromosome disorders later.
Practice Problem
Protein
Result
Phe – Pro – Trp
Normal
Phe – Ser– Arg
Mind Control
Phe – Arg
Telekinesis
Phe – Trp
X-Ray Vision
Phe – Ser – Trp
Superhuman Strength
Oh no, Ms. Becerra’s DNA polymerase made a mistake! This caused a substitution
mutation in her DNA. Replace Normal DNA Base #4 with an A, and replace #7 with an T.
NORMAL DNA:
A A G–G G C–A C C
Type of Mutation: Substitution Mutation
MUTATED DNA:
A A G–A G C–T C C
NEW RNA:
U U C–U C G–A G G
Phe – Ser – Arg
NEW PROTEIN:
MIND
CONTROL!
TERATOMA!!!
Learning Log – 11/30 – Page 72
need to
know
warm up
Copy the following:
• How to read mutation problems carefully!
Answer the following:
1. What type of mutation happened below?
Normal DNA: TATGGCAAC
Mutant DNA: TATGCAAC
Learning Log – 12/2 – Page 72
need to
know
Copy the following:
• Review: How does protein synthesis
happen in the cell?
warm up
Answer the following:
1. What happens to a protein after it’s
made?
Learning Log – 12/3 – Page 72
need to
know
warm up
Copy the following:
• Why do we have different cells even
though the DNA (instructions) are the
same?
NONE – WONDERWALL!
New Life Form??