mutations

• what is a mutation?


  a change in the DNA base sequence
• when do mutations occur?

  spontaneously
• what increases the risk of mutations?

  -carcinogens

  -certain types of radiation
• what happens if a triplet code changes?


  the sequence of amino acids would be different and have a different shape or function
• does a mutation have a significant effect most of the time?

  no
• when do mutations mostly occur?


  in non coding DNA which doesn’t code for a protein
• what are the three types of mutations?


  -substitutions

  -insertions

  -deletions
• what is a substitution mutation?


  when one of the bases is changed for another random base
• what is the problem of substitutions?


  could change the codon and therefore change the amino acid that it codes for
• what is an insertion mutation?


  an extra base is inserted in the sequence
• what is the problem of insertion mutations?


  the bases shift along by one which alters all the codons, the amino acid chain after that point would be completely different
• what is a deletion mutation?


  one of the bases is deleted from the sequence
• what is the problem of deletion mutations?


  all the codons after the deletion mutation would be altered
• what are carcinogens?


  found in cigarette smoke