When is a single base substitution mutation least likely to be deleterious?

What can happen to the amino acid sequence when there is a base substitution mutation in a strand of dna?

• Answer:

  Any of these: 1. Nothing because most eukaryotic DNA doesn't code for an amino acid sequence or have a function that's critical to an amino acid sequence 2. No amino acid sequence is made because an important consensus sequence such as a promoter got trashed 3. Nothing because the genetic code is "degenerate" -- the mutation is a "synonymous mutation." 4. A different amino acid is put into the amino acid sequence. This is a "missense mutation." 5. The polypeptide ends, because the mutation changed a codon that coded for an amino acid into a stop codon. This is a "nonsense mutation." 6. The polypeptide gets extended because the mutation changed a stop codon into a codon that codes for an amino acid. Look up amber, ochre, and opal.