DNA Mutations

• What is the definition of a mutation?


  A change in the DNA base sequence
• What can cause mutations in DNA?


  Mutations can be caused by spontaneous changes during DNA duplication and by carcinogens or radiation.
• What are carcinogens?


  A group of harmful chemicals that increase the risk of mutations.
• How do carcinogens and radiation affect mutations?


  They increase the risk of a mutation occurring but do not always cause mutations.
• What is a gene?


  A section of DNA that codes for a protein.
• What is a triplet or codon?


  A group of 3 bases that codes for one of the 20 different amino acids.
• How does a mutation in DNA affect protein synthesis?


  A mutation can change the amino acid sequence, potentially altering the protein's shape and function.
• What happens if a mutation changes an amino acid in an enzyme?


  The enzyme's active site may change, preventing it from fitting the substrate and forming an enzyme-substrate complex.
• What is the typical effect of most mutations?


  Most mutations have no significant effect on protein function.
• What is non-coding DNA?


  DNA that does not code for proteins and often does not seem to have a function.
• Why might non-coding DNA be important?


  Some non-coding DNA plays a role in the expression of genes, determining whether they are turned on or off.
• What are the three specific types of mutations?

  Substitutions, insertions, and deletions.
• What is a substitution mutation?


  A mutation where one base is changed or substituted for another base.
• Why are insertion mutations considered worse than substitution mutations?


  Insertion mutations shift all subsequent bases, altering all following codons and amino acids.
• What happens during a deletion mutation?


  A base is removed from the sequence, causing all subsequent bases to shift left and change the following codons.
• What are the consequences of mutations on proteins?


  • Mutations can change the amino acid sequence.
  • This may alter the protein's shape and function.
  • Some mutations have no significant effect.
  • Most mutations occur in non-coding DNA.
• How do the three types of mutations differ from each other?

  • Substitution: One base is changed for another.
  • Insertion: An extra base is added, shifting subsequent bases.
  • Deletion: A base is removed, also shifting subsequent bases.