mutations exam III.txt

Card Set Information

mutations exam III.txt
2011-12-04 12:56:05

Show Answers:

  1. mutation causes…
    • change in RNA
    • change in protein
    • change in shape and function
  2. mutation definition
    heritable change in genetic behavior NOT caused by recombination
  3. Germinal mutation
    mutation which alters fxn in cells... can give rise to gametes, which are passed onto the next generation
  4. Somatic mutation
    mutation occurring in non-sex (somatic cells) and are NOT passed onto progeny except in plants they can be germinal
  5. Types of mutations based on lesion
    • 1. point mutations
    • 2. missense mutations
    • 3. nonsense mutations
    • 4. silent mutations
    • 5. neutral mutations
    • 6. frameshift mutations
  6. Type of mutation based on fxn
    • 1. amorphic
    • 2. hypomorphic
    • 3. hypermorphic
    • 4. antimorphic
    • 5. neomorphic
  7. Point mutations
    • affects single basepair
    • a. transition: a purine replaces a purine or vice versa
    • b. tranversion: a purine replaces a pyrimidine or vice versa
  8. Missense mutation
    one basepair changes the amino acid
  9. Nonsense mutation
    • basepair change causes the change of an aa to a STOP codon
    • Protein is usually NONfunctional
  10. Silent mutation
    basepair change results in the SAME aa (b/c multiple codes for one aa)
  11. Neutral mutation
    • basepair change substitutes a RELATED amino acid
    • No overall change in function
    • ie: Lys-->Arg
  12. Frameshift mutation
    • addition or deletion of a basepair shifting the reading frame of mRNA so ribosome incorporates wrong aa during translation
    • protein is NONfunctional
  13. Amorphic mutation
    Loss of function (Null)
  14. Hypomorphic mutation
    Partial LOSS of fxn (leaky)
  15. Hypermorphic mutation
    Increase in fxn (Overproducer)
  16. Antimorphic***
    • antagonized wildtype (normal)
    • Knockout (KO) - reduces fxn of the WT gene product
  17. Neomorphic
    • Gain of a NEW function, usually dominant
    • mutant gene expressed at a new time & place during development
  18. mutation reversions
    • bp change that restores its fxn
    • forward mutation: normal --> mutant
    • reverse mutation: mutant --> normal (REVERTS back to normal)
  19. suppression w/types
    • mutation @ a 2nd site that partially or fully RESTORES fxn lost b/c of mutation @ other site
    • 1. Intergenic suppressor: mutation in 1 gene corrects effects of mutation from another gene
    • 2. Intragenic suppressor: suppressor mutation w/in the same gene
    • ie a bp addition near a bp deletion
  20. Causes of mutations
    • Spontaneous mutations
    • Induced mutations
  21. Spontaneous mutations
    • 1. transposable elements of DNA (major cause): called JUMPING genes
    • discovered thru working w/corn to see patterns of colors
    • 2. Defective subunits of DNA pol III: the pol III usually has proofreading fxn that removes wrong nucleotides, but if it's defective
    • 3. Base tautomers: change in base structure that causes them to mispair. ie A-G, A-C
  22. Induced mutations
    • mutagen: any agent that can induce mutations in DNA
    • 1. X-Rays: 1st mutagenic agent discovered…usually breaks DNA strands
    • 2. UV light: causes covalent crosslinking b/w bases of DNA, usually Thymine
    • 3. THymine dimers: interfere w/basepairing, leading to insertion of incorrect nucleotide (these mutations can cause skin cancer)