9.1 Gene mutation
,What are mutations?
• Changes to the quantity or sequence of bases in DNA
• Can be just one nucleotide
• May be inherited or happen during cell division
• How do mutations affect proteins?
• DNA change may change amino acid sequence change in bonding
new tertiary structure may no longer function
, Substitution of bases
• A nucleotide is replaced by another nucleotide
with a different base
• This may affect which amino acid it codes for
• Only one amino acid is affected in most cases
• If this amino acid was important in bonding then it
might affect the tertiary structure
• No effect: if the new codon codes for the same
amino acid
• If the new codon is a stop codon, then the rest of
the polypeptide wont be produced
,What are mutations?
• Changes to the quantity or sequence of bases in DNA
• Can be just one nucleotide
• May be inherited or happen during cell division
• How do mutations affect proteins?
• DNA change may change amino acid sequence change in bonding
new tertiary structure may no longer function
, Substitution of bases
• A nucleotide is replaced by another nucleotide
with a different base
• This may affect which amino acid it codes for
• Only one amino acid is affected in most cases
• If this amino acid was important in bonding then it
might affect the tertiary structure
• No effect: if the new codon codes for the same
amino acid
• If the new codon is a stop codon, then the rest of
the polypeptide wont be produced
