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Mutations or "DNA out of control'

Mutations or "DNA out of control'. Mutations (p. 262) What are mutations? Mutations are changes in the DNA sequence that are inherited. Do mutations have negative, neutral or positive side effects on an organism ? Where do mutations occur? somatic (body) cells

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Mutations or "DNA out of control'

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  1. Mutationsor "DNA out of control'

  2. Mutations (p. 262) What are mutations? • Mutations are changes in the DNA sequence that are inherited. Do mutations have negative, neutral or positive side effects on an organism? Where do mutations occur? somatic (body) cells gametes (reproductive cells)

  3. Causes of mutations Changes to the base pair sequence of genetic material (either DNA or RNA) that are: Spontaneous • copying errors in the genetic material during cell division Mutagenic • exposure to UV radiation, natural background radiation, chemical mutagens, or viruses

  4. See pg 265 for more info!

  5. Cancer Diagnosis/Treatment

  6. When can mutations occur?

  7. Result of Point Mutations In order of increasing severity: 1. silent mutation changes between 2 codons for the same amino acid GCU GCC Ala Ala 2. missense mutation the coded amino acid changes to a different AGA AGU Amino acid Arg Ser 3. nonsense mutation changes the coded amino acid to a stop codon UAUUAA Tyr STOP 4. frameshift mutation changes the reading frame GCU AGU AAU GCU AGA AU Ala Ser Asp Ala Arg

  8. Types of Mutations 1) Substitution: exchanging of one nucleotide for another does not change reading frame, but changes codon • (silent, missense, nonsense mutations)

  9. 2) Deletion: loss of one or more nucleotides changes the reading frame (frameshift mutation)

  10. 3)Insertion (Addition): • gain of one or more nucleotides • changes the reading frame (frameshift mutation)

  11. Summary

  12. Chromosomal Mutations 1) Translocation: -a section of DNA moves from one chromosome to another -can inactivate a gene if the section is part of an exon or promoter

  13. 2) Inversion: -a section of DNA from one strand exchanges with an section of DNA from the other strand -can inactivate a gene if the section is part of an exon or promoter

  14. Cancer and Disease • Knudson’s Two-Hit Theory • Carcinogenesis (development of cancer) requires: • Activation of oncogenes (genes that promote cell growth and division) • Deactivation of tumour suppressor genes (genes that prevent cell growth and division or cause programmed cell death – apoptosis) • Both alleles (two-hit) must be affected • If one is normal, it will still make the correct protein

  15. At each checkpoint, the cell undergoes screening to make sure it is healthy. If a mutations is found the cell will undergo apoptosis. Sometimes mutations go undetected, continue to replicate andcan form cancer.

  16. http://www.youtube.com/watch?v=mHOX43-4PvE • stop at 1:13 • Homework pg 262-265 • #19-24 • Homework • Page 259-263 • Questions1-7

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