Understanding Mutations in DNA and Their Effects

 
Notes on Mutations
 
 
A change in DNA
 
M
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a
 
c
h
a
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g
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D
N
A
 
                    -not all mutations are harmful
 
                    -can happen in body cells and in gametes.
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p
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Substitution
: one base is substituted for another
 
      
  
         ACTTAGGC 
   
 AC
A
TAGGC
 
Insertion
: a base is added
 
      
  
        ACTTAGGC 
   
 ACTTAGGC
T
 
Deletion
: a base is removed
 
      
  
       ACTTAGGC 
  
  
 
 ACTTAGG__
 
M
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Ex: x-rays, UV light, radiation, chemicals, smoking, sun ta
Mutations
 
Mutations are changes in DNA sequences
changes to the order of A, T, C & G
different order = different amino acid in protein
different protein structure = different protein
function
B
b
b
b
B
B
Mutations
 
Point mutations
single base change
silent mutation
no amino acid change
redundancy in code
missense
change amino acid
nonsense
change to stop codon
Point mutation leads to Sickle cell anemia
What kind of mutation?
Missense
!
Sickle cell anemia
 
Primarily Africans
recessive inheritance pattern
strikes 1 out of 
400
 African Americans
Mutations
 
Frameshift
shift in the 
reading
frame
changes everything
“downstream”
insertions
adding base(s)
deletions
losing base(s)
Where would this mutation 
cause the most change:
beginning or end of gene? 
T
H
E
R
A
A
T
A
N
D
T
H
E
C
A
T
A
T
E
T
H
E
R
E
D
B
A
T
T
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A
A
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N
D
T
H
E
C
A
T
A
T
E
T
H
E
R
E
D
B
A
T
Frameshift mutations
T
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A
T
A
N
D
T
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C
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T
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T
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D
B
A
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T
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N
D
T
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C
A
T
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T
H
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R
E
D
B
A
T
T
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R
A
T
A
N
D
T
H
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C
A
T
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T
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T
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R
E
D
B
A
T
T
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T
A
N
D
T
H
E
C
A
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B
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Cystic fibrosis
 
Primarily whites of
European descent
strikes 1 in 
2500
 births
1 in 25 whites is a carrier (Aa)
normal allele codes for a membrane protein
that moves Cl
-
 across cell membrane
mutant channel limit movement of Cl
-
 (& H
2
O) across cell
membrane
thicker & stickier mucus coats cells
mucus build-up in the pancreas, lungs, digestive tract & causes
bacterial infections
without treatment children die before 5;
with treatment can live past their late 20s
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Mutations in DNA are changes that can occur in body cells or gametes, leading to alterations in the genetic code. Not all mutations are harmful, but they can impact protein structure and function. Different types of mutations, such as substitutions, insertions, and deletions, can result from various factors including mutagens in the environment. Point mutations, like missense changes, can have significant consequences, like in the case of sickle cell anemia. Frameshift mutations, which alter the reading frame of genes, can cause significant downstream effects. Understanding these mutations is crucial in comprehending genetic disorders and inheritance patterns.


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  1. Notes on Mutations A change in DNA

  2. Mutations Mutation Mutation: a change in DNA -not all mutations are harmful -can happen in body cells and in gametes. ** **mutations are passed down to offspring only when they are in the gametes ** ** Types of Mutations Types of Mutations Substitution: one base is substituted for another ACTTAGGC ACATAGGC Insertion: a base is added ACTTAGGC ACTTAGGCT Deletion: a base is removed ACTTAGGC ACTTAGG__

  3. Mutagens: Mutagens: factors in the environment that cause mutations Ex: x-rays, UV light, radiation, chemicals, smoking, sun ta https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcQAazMOfKKyRFeYB_ZTfV4jWedLtNM9wAFm5xzbnV2FEIWylj2txkdgea1D https://encrypted-tbn1.gstatic.com/images?q=tbn:ANd9GcTHeWDfxdiK1ALAO0HqhZEWMDd1XlPGJOukbGhJFxZvg3EKkwI29HZEKQ71 https://encrypted-tbn1.gstatic.com/images?q=tbn:ANd9GcQT5cWEqb9yYmyaOzE3gYrfMrV24gY7rW9a2cNfAOaal8rnX7VetwPaCw

  4. Mutations Mutations are changes in DNA sequences changes to the order of A, T, C & G different order = different amino acid in protein different protein structure = different protein function BB Bb bb

  5. Mutations Point mutations single base change silent mutation no amino acid change redundancy in code missense change amino acid nonsense change to stop codon

  6. Point mutation leads to Sickle cell anemia What kind of mutation? Missense!

  7. Sickle cell anemia Primarily Africans recessive inheritance pattern strikes 1 out of 400 African Americans

  8. Mutations Frameshift shift in the reading frame changes everything downstream insertions adding base(s) deletions losing base(s) Where would this mutation cause the most change: beginning or end of gene?

  9. Frameshift mutations THERATANDTHECATATETHEREDBAT THERATANDTHECATATETHEREDBAT Deletion THERTANDTHECATATETHEREDBAT THERTANDTHECATATETHEREDBAT Insertion THERAATANDTHECATATETHEREDBAT THERAATANDTHECATATETHEREDBAT

  10. Cystic fibrosis Primarily whites of European descent strikes 1 in 2500 births 1 in 25 whites is a carrier (Aa) normal allele codes for a membrane protein that moves Cl- across cell membrane mutant channel limit movement of Cl- (& H2O) across cell membrane thicker & stickier mucus coats cells mucus build-up in the pancreas, lungs, digestive tract & causes bacterial infections without treatment children die before 5; with treatment can live past their late 20s

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