POINT MUTATIONS

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POINT MUTATIONS

• Not like X-Men

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MUTATION

• Any change in the genetic sequence (DNA) that
  affects the genetic information

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POINT MUTATIONS

• Occurs at 1 single point in DNA
• These could cause one amino acid to change, which
  would change the protein that is being produced.

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POINT MUTATIONS

• BASE SUBSTITUTION
• A nucleotide is replaced with a different
  nucleotide.
• Three examples
• Transversion mutation
• Transition mutation
• Silent mutation

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BASE SUBSTITUTIONExamples

• Transversion happens when one purine (A,G) is
  swapped with a pyrimidine (C,T).
• DNA CTT to CAT
• mRNA GAA to GUA
• AA Glu to Val

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Transversion Substitution
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BASE SUBSTITUTIONExamples

• transition mutations happen when one purine is
  swapped with the other purine or a pyrimidine is
  swapped with a pyrimidine.
• DNA CTT to CCT
• mRNA GAA to GGA
• AA Glu to Gly

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BASE SUBSTITUTIONExamples

• Silent mutations happen when a base codon is
  changed but both code for the same amino acid.
• DNA GAA to GAC
• mRNA CUU to CUG
• AA Leu to Leu

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POINT MUTATIONS

• FRAMESHIFT Because of a point mutation, there
  is a shift in the reading frame of genetic
  message
• Almost always affect all the amino acids after
  the mutation, which will affect the entire
  protein.

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Frameshift Mutation Examples

• Insertion
• Shifts the reading to the right
• DNA from GCATCG to GCC ATC
• mRNA from CGU AGC to CGG UAG
• Amino
• Acid from Arg Ser to Arg STOP

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Point Mutation

• Deletion
• Shifts the reading to the left
• DNA from GCATCG to GAT CG
• mRNA from CGU AGC to CUA GC
• Amino
• Acid from Arg Ser to Leu

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A New Subtype of Brachydactyly Type B Caused by
Point Mutations in the Bone Morphogenetic Protein
Antagonist NOGGIN
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Hutchinson-Gilford progeria syndrome The
disease is caused by a small point mutation on a
single gene known as LMNA. Almost all cases are
caused by the substitution of only one base pair
out of the approximate 25 000 DNA base pairs that
compose the LMNA gene. This gene codes for the
protein lamin A, which is important to determine
the shape of a cells nucleus. It is vital in
providing support to the nucleus inner membrane.
The mutation in the LMNA gene causes an abnormal
form of the lamin A protein. That malformed
protein makes the inner cell membrane unstable
and little by little damages the nucleus this
makes cells more prone to die prematurely.
Researchers are still trying to figure out how
exactly this leads to the phenotypes associated
with progeria.
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CHROMOSOMAL MUTATIONS
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INVERSION and TRANSLOCATION

• Inversion 2 sections of the chromosome are
  reversed
• Translocation 1 part of a chromosome breaks off
  and attaches to another part of a chromosome
• Duplication Part of chromosome is copied

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Examples

• ORIGINAL CHROMOSOME
• ABCDEFG where the letters are representing
  genes on the chromosome.
• Inversion ABGFEDC
• Translocation ABCDXYZ
• Duplication ABBBCDEFG

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Inversion

• Brenden Adams abnormal growth rate is due to an
  inversion in chromosome-12, a growth gene defect
  that skyrocketed his growth rate.

In Brendens case, his 12th chromosomes dont
match. Experts dont know why, but the middle of
one of them broke off, flipped around and
re-attached at the zygote stage of development,
disrupting a critical gene that controls growth.
http//www.kimatv.com/news/local/11161021.html?tab
video
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Translocation Examples

• Acute Promyelocytic Leukemia caused by a
  rearrangement of genetic material between
  chromosome 9 and 22.

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Translocation Examples

• The section on 15 is responsible for suppressing
  tumors (control growth). The section on 17 is
  responsible for helping white blood cells mature.
  When the two are translocated, tumors can grow
  and white blood cells cannot mature.
• It is aquired not inherited.

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Translocation
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Translocation
A chromosome 512 translocation causes severe
skeletal and composite cardiac malformations.
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Duplication
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Deletion

• a portion of one chromosome is lost during cell
  division. That chromosome is now missing certain
  genes. When this chromosome is passed on to
  offspring the result is usually lethal due to
  missing genes.

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Chromosome New Chromosome Mutation
AbcdEFghijklm Abcdkjlm 1
AbcdEFghijklm AbihgFEdcjklm 2
AbcdEFghijklm AcdEFghijklm 3
AbcdEFghijklm AbcdEFghiWxYz 4
AbcdEFghijklm AbcdbcdEFghijklm 5
AbcdEFghijklm AbcdEFkjihglm 6
AbcdEFghijklm AbcdEFdEFghijklm 7
AbcdEFghijklm Abcdmlkjhg 8
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Chromosome New Chromosome Mutation
AbcdEFghijklm Abcdkjlm 1 Deletion Inversion
AbcdEFghijklm AbihgFEdcjklm 2 Inversion
AbcdEFghijklm AcdEFghijklm 3 Deletion
AbcdEFghijklm AbcdEFghiWxYz 4 Translocation
AbcdEFghijklm AbcdbcdEFghijklm 5 Duplication
AbcdEFghijklm AbcdEFkjihglm 6 Inversion
AbcdEFghijklm AbcdEFdEFghijklm 7 Duplication
AbcdEFghijklm Abcdmlkjhg 8 Deletion Inversion
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• http//www.chemistryexplained.com/Ma-Na/Mutation.h
  tml
• http//embryology.med.unsw.edu.au/Defect/page21.ht
  m
• http//www.biology.arizona.edu/human_bio/activitie
  s/karyotyping/karyotyping.html
• http//www.docstoc.com/docs/38810096/Mutations