1 / 17

Mutations

Mutations. Categories of Mutations by Type. Deletions Inversions Insertions Duplications Point mutations Change of a single nucleotide in the DNA Nucleotide change – transition or transversion Single nucleotide insertion Single nucleotide deletion. Categories of Mutations by Affect.

zitkalasa
Download Presentation

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. Categories of Mutations by Type • Deletions • Inversions • Insertions • Duplications • Point mutations • Change of a single nucleotide in the DNA • Nucleotide change – transition or transversion • Single nucleotide insertion • Single nucleotide deletion

  3. Categories of Mutations by Affect • Regulatory • Affect production or steady state levels of gene product • promoters, splicing sequences, ribosome binding sites • Structural (Coding) • Affect actual sequence of gene product • point mutations within coding sequence • Silent • a change in DNA sequence that has no detectable affect on gene expression or gene product function • SNP – single nucleotide polymorphisms

  4. Point Mutations in Coding Sequences Missense – changes amino acid Nonsense – creates stop codon Frameshift – alters remainder of reading frame results in completely different amino acid sequence.

  5. Base Changes • Transitions • pyrimidine replaces pyrimidine - C to T or T to C • purine replaces purine – G to A or A to G • GC changed to A=T or vice versa • Most common base change • Transversion • purine replaces pyrimidine or vice versa • G to C or T • A to C or T • C to G or A • T to G or A • GC changed to CG or T=A • Rare

  6. Tautomeric Shifts Lead to Transitions Figure 16.10

  7. Normal amino-A = keto-T amino-C  keto-G Tautomeric imino-A = amino-C amino-A = imino-C enol-T  keto-G keto-T  enol-G Tautomeric Base-Pairing

  8. Tautomeric Shifts Alter Base-Pairing Specificity

  9. Tautomer Figure 16.10

  10. Modification of Bases by Alkylating Agents EMS – ethylmethane sulfonate DMS – Dimethyl sulfonate ENU - Ethylnitrosourea

  11. Alkylation Leads to Transitions

  12. Deamination leads to Transitions

  13. Oxidative DNA Damage Leads to Transversion Mutations free radicals

  14. Intercalation Leads to Insertions/Deletions

  15. Ionizing Radiation DNA Damage VIS

  16. Shortwave UV (UVA) Causes Thymidine Dimers

  17. X-rays & γ-rays Cause DNA Strand Breaks

More Related