Read the summary and the most important questions on Studyguide for Igenetics A Molecular Approach by Peter J. Russell, ISBN 9780805346657 | 9781616984571 | Cram101 Textbook Reviews

• 7 DNA mutation, DNA repair and transposable elements

• 7.1.2 Mutations defined

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• What is the difference between a "somatic mutation"  and a "germ-line mutation" ? (2)

  • Somatic mutation: affects only the individual itself
  • Germ-line mutation: may be passed on, and create mutations in both somatic cells as germ-line cells in next generation

• What is a "phenotype" ?

  The observable characteristics of an organism are produced by the genotype and its interaction with the environment

• What is a "genotype" ?

  The complete genetic make up (allele composition) of an organism

• What is a "nonsense mutation" ?

  A base pair change alters an mRNA codon for an amino acid to a stop (nonsense) codon

  • UAG
  • UAA
  • UGA

• What is a "neutral mutation" ? (2)

  • Base pair change in a gene that changes a mRNA codon in a way that the resulting amino acid substitution results no detectable change in the function of the protein being translated
    
  • Subset of missense mutations that does not result in a change of the protein

• What is a "silent mutation" ? (3)

  • Synonymous mutation
  • Changes a base pair but the altered mRNA codon specifies the same amino acid in the protein
  • Happens often on the 3rd position of a codon

• What is a "frameshift mutation" ? (3)

  • If 1 or more base pairs are added or deleted from a protein coding gene
  • the reading frame of an mRNA can change downstream of the mutation

  
  

  Usually results in a non-functioning protein
  

  • Stopcodon
  • Polypeptide too long
  • Significant alteration of amino acid sequence

• How can mutations be classified? (3)

  Cause: 

  • spontaneous vs. induced
    

  
  

  Effect on DNA: 
  

  • point vs. chromosomal
  • substitution vs. insertion/deletion
  • transition vs. transversion

  
  

  Effect on an encoded protein:

  • Nonsense
  • Missense
  • Neutral
  • Silent
  • Frameshift

• 7.1.3 Spontaneous and induced mutations

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• Characteristics of DNA replication errors? (5)

  • base pair substitution mutations
  • point mutation
  • change of one base pair to another
  • mismatched base pairs during replication
  • enol form of base (instead of keto form)
  • Repair by "mismatch repair systems"

• What is a "tautomer" ? (2)

  • Alternate chemical forms in which DNA or RNA bases can exist
  • Keto (normal) --> Enol (rare)