DNA mutations

Question 1

what is a silent mutation?

Answer 1

when a nucleotide substitution results in a different codon that still encodes the same amino acid

Question 2

what is the consequence of a silent mutation?

Answer 2

the protein is unaffected so their is no function difference

Question 3

what is a missense mutation?

Answer 3

nucleotide substitution results in a codon that encodes a different amino acid

Question 4

what is the consequence of a missense mutation?

Answer 4

the primary protein sequence is altered which can be radical or conservative:
radical- new amino acid R group different in charge or size= potential altered secondary or tertiary structure affecting function
conservative- similar amino acid R group size and charge = similar protein shape and function

Question 5

what is a nonsense mutation?

Answer 5

nucleotide substitution results in a stop codon that stops translation

Question 6

what is the consequence of nonsense mutations?

Answer 6

• protein truncated and so may not function properly or at all
• Nonsense Mediated Decay (NMD)

Question 7

what is nonsense-mediated decay?

Answer 7

process during translation that detects transcripts with premature stop codons and degrades them

Question 8

what are insertion mutations?

Answer 8

changes the number of nucleotides in a gene by adding a piece of DNA

Question 9

what is the consequence of a insertion mutation?

Answer 9

FRAMESHIFT MUTATION
Every nucleotide in the gene is shifted along by one downstream from the insertion, therefore the resulting mRNA will be shifted one. Different amino acids will be incorporated so the gene may not function.

Question 10

what is a deletion mutation?

Answer 10

removes a piece of DNA

Question 11

what is the consequence of a deletion mutation?

Answer 11

FRAMESHIFT MUTATION
every nucleotide is shifted up one therefore different amino acids are incorporated resulting in potential alter of function