1 / 13

Mutations

Mutations. Figure 14.25. Mutations. Sickle-cell hemoglobin. Wild-type hemoglobin. Mutant hemoglobin DNA. Wild-type hemoglobin DNA. changes in the genetic material Point mutations changes in one or a few nucleotide pairs of a gene can lead to the production of an abnormal protein. A. C.

oprah
Télécharger la présentation

Mutations

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Mutations

  2. Figure 14.25 Mutations Sickle-cell hemoglobin Wild-type hemoglobin Mutant hemoglobin DNA Wild-type hemoglobin DNA • changes in the genetic material • Point mutations changes in one or a few nucleotide pairs of a gene • can lead to the production of an abnormal protein A C C C C 5 T 5 3 3 G G T A 3 G G 3 5 5 mRNA mRNA G G A G G 3 5 U 5 3 Sickle-cell hemoglobin Normal hemoglobin Glu Val

  3. Sickle Cell Anemia

  4. Figure 14.26a Substitutions Wild type DNA template strand 3 5 T A C T T C A A A C C G A T T 5 3 A T G A A G T T T G G C T A A • A nucleotide-pair substitution replaces one nucleotide and its partner with another pair of nucleotides • Silent mutationshave no effect on the amino acid produced by a codon because of redundancy in the genetic code mRNA 5 3 A U G A A G U U U G G C U A A Protein Lys Gly Met Phe Stop Amino end Carboxyl end Nucleotide-pair substitution: silent A instead of G 3 T A C T T C A A A C C A A T T 5 5 3 A T G A A G T T T G G T T A A U instead of C 5 3 A U G A A G U U U G G U U A A Lys Gly Met Phe Stop

  5. Gene mutation: Substitution

  6. Figure 14.26b Substitutions Wild type DNA template strand 3 T A C T T C A A A C C G A T T 5 5 3 A T G A A G T T T G G C T A A • Missense mutations still code for an amino acid, but not the correct amino acid • Substitution mutations are usually missense mutations mRNA 5 3 A U G A A G U U U G G C U A A Protein Lys Gly Met Phe Stop Amino end Carboxyl end Nucleotide-pair substitution: missense T instead of C 5 3 T A C T T C A A A T C G A T T 5 3 A T G A A G T T T A G C T A A A instead of G 5 3 A U G A A G U U U A G C U A A Lys Ser Met Phe Stop

  7. Figure 14.26c Substitutions Wild type DNA template strand T A C T T C A A A C C G A T T 3 5 5 3 • Nonsense mutations change an amino acid codon into a stop codon, usu. a nonfunctional protein A T G A A G T T T G G C T A A mRNA 5 3 A U G A A G U U U G G C U A A Protein Lys Gly Met Phe Stop Amino end Carboxyl end Nucleotide-pair substitution: nonsense A instead of T 3 T A C A T C A A A C C G A T T 5 5 3 A T G T A G T T T G G C T A A U instead of A 5 3 A U G U A G U U U G G C U A A Met Stop

  8. Figure 14.26d Insertions and Deletions Wild type DNA template strand 3 5 T A C T T C A A A C C G A T T • Insertions and deletions are additions or losses of nucleotide pairs in a gene • disastrous effects on the resulting protein • may alter the reading frame, producing a frameshift mutation 5 3 A T G A A G T T T G G C T A A mRNA 5 3 A U G A A G U U U G G C U A A Protein Lys Gly Met Phe Stop Amino end Carboxyl end Nucleotide-pair insertion: frameshift causing immediate nonsense Extra A 3 5 T A C A T T C A A A C C G A T T 5 3 A T G T A A G T T T G G C T A A Extra U 3 5 A U G U A A G U U U G G C U A A Met Stop

  9. Gene Mutation: Deletion or Insertion?

  10. Gene Mutation: Deletion Insertion

  11. Figure 14.26e w/Frameshift Wild type DNA template strand 3 5 T A C T T C A A A C C G A T T 5 3 A T G A A G T T T G G C T A A mRNA 5 3 A U G A A G U U U G G C U A A Protein Lys Gly Met Phe Stop Amino end Carboxyl end Nucleotide-pair deletion: frameshift causing extensive missense missing A 5 3 T A C T T C A A C C G A T T 3 5 G A T G A A G T T G C T A A missing U 5 3 A U G A A G U U G G C U A A Leu Lys Ala Met

  12. Figure 14.26f w/no frameshift Wild type DNA template strand 3 T A C T T C A A A C C G A T T 5 5 3 A T G A A G T T T G G C T A A mRNA 5 3 A U G A A G U U U G G C U A A Protein Lys Gly Met Phe Stop Amino end Carboxyl end 3 nucleotide-pair deletion: no frameshift, but one amino acid missing missing T T C 5 3 T A C A A A C C G A T T 3 5 A T G T T T G G C T A A missing A G A 5 3 A U G U U U G G C U A A Met Phe Gly Stop

  13. Mutagens • Spontaneous mutationscan occur during DNA replication, recombination, or repair • Mutagens are physical or chemical agents that can cause mutations • Most carcinogens are mutagenic and visa versa

More Related