Question

mutation - a change in the dna
point mutations - when a single nitrogen base is deleted, inserted or substituted.
frameshift mutation- when many amino acids coded for are different because of an insertion or deletion.
the following example shows how these 3 kinds of mutations work. fill out the rna and protein for each and compare the mutations to the original. the mutation is in bold.
original dna tac gcg tgc acg atg cag tag tac
rna
protein
mutation 1 dna tac gcg tgc acg atc cag tag tac
rna
protein
type of mutation:
mutation 2 dna tac gcg tgc tcg atg cag tag tac
rna
protein
type of mutation:
mutation 3 dna tac gcg ctg cac gat gca gta gta c
rna
protein
type of mutation:

Explanation:

Step1: Transcribe DNA to RNA

• For the original DNA: TAC GCG TGC ACG ATG CAG TAG TAC
• RNA is transcribed as AUG CGC ACG UGC UAC GUC AUC AUG (using base - pairing rules: A - U, T - A, G - C, C - G)
• For Mutation 1 DNA: TAC GCG TGC ACG ATC CAG TAG TAC
• RNA is AUG CGC ACG UGC UAG GUC AUC AUG
• For Mutation 2 DNA: TAC GCG TGC TCG ATG CAG TAG TAC
• RNA is AUG CGC ACG AGC UAC GUC AUC AUG
• For Mutation 3 DNA: TAC GCG CTG CAC GAT GCA GTA GTAC
• RNA is AUG CGC GAC GUG CUA CGU CAU CAUG

Step2: Translate RNA to Protein (using the genetic code)

• Original RNA: AUG (Met), CGC (Arg), ACG (Thr), UGC (Cys), UAC (Tyr), GUC (Val), AUC (Ile), AUG (Met)
• Mutation 1 RNA: AUG (Met), CGC (Arg), ACG (Thr), UGC (Cys), UAG (Stop), GUC (Val), AUC (Ile), AUG (Met)
• Mutation 2 RNA: AUG (Met), CGC (Arg), ACG (Thr), AGC (Ser), UAC (Tyr), GUC (Val), AUC (Ile), AUG (Met)
• Mutation 3 RNA: AUG (Met), CGC (Arg), GAC (Asp), GUG (Val), CUA (Leu), CGU (Arg), CAU (His), CAUG (incomplete, but looking at codons: CAU - His)

Step3: Determine Mutation Type

• Mutation 1: A single base (G→C in DNA, which is a substitution. So it is a point mutation.
• Mutation 2: A single base (A→T in DNA, which is a substitution. So it is a point mutation.
• Mutation 3: Insertion (an extra base), which causes a frameshift mutation as it changes the reading frame for subsequent codons

Answer:

Original RNA: AUG CGC ACG UGC UAC GUC AUC AUG
Original Protein: Met - Arg - Thr - Cys - Tyr - Val - Ile - Met
Mutation 1 RNA: AUG CGC ACG UGC UAG GUC AUC AUG
Mutation 1 Protein: Met - Arg - Thr - Cys - Stop (truncated)
Mutation 1 Type: Point Mutation
Mutation 2 RNA: AUG CGC ACG AGC UAC GUC AUC AUG
Mutation 2 Protein: Met - Arg - Thr - Ser - Tyr - Val - Ile - Met
Mutation 2 Type: Point Mutation
Mutation 3 RNA: AUG CGC GAC GUG CUA CGU CAU CAUG
Mutation 3 Protein: Met - Arg - Asp - Val - Leu - Arg - His (incomplete due to codon - reading issues from insertion)
Mutation 3 Type: Frameshift Mutation