NAME __________________________________ Mutations Worksheet

Question

Deletion, Insertion & Substitution
There are several types of mutation:
➢ DELETION (a base is lost/deleted)
➢ INSERTION (an extra base is added/inserted)
--- Deletion & insertion may cause what’s called a FRAMESHIFT mutation, meaning the reading “frame"
changes, thus changing the amino acid sequence from this point forward
➢ SUBSTITUTION (one base is substituted for another)
--- If a substitution changes the amino acid, it’s called a MISSENSE mutation
--- If a substitution does not change the amino acid, it’s called a SILENT mutation
--- If a substitution changes the amino acid to a “stop,” it’s called a NONSENSE mutation
Complete the boxes below. Classify each as Deletion, Insertion or Substitution AND as either
frameshift, missense, silent or nonsense (Hint: Deletion & Insertion will always be frameshift).
ORIGINAL DNA Sequence ➔ T A C A C C T T G G C G A C G A C T
What is the mRNA sequence?
amino acid sequence?
MUTATED DNA Sequence #1 ➔ T A C A T C T T G G C G A C G A C T
What is the mRNA sequence? (Circle the change)
amino acid sequence?
Will there likely be effects? What type of mutation is this? ______________________________
MUTATED DNA Sequence #2 ➔ T A C G A C C T T G G C G A C G A C T
What is the mRNA sequence? (Circle the change)
amino acid sequence?
Will there likely be effects? What type of mutation is this? ______________________________
MUTATED DNA Sequence #3 ➔ T A C A C C T T A G C G A C G A C T
What is the mRNA sequence? (Circle the change)
amino acid sequence?
Will there likely be effects? What type of mutation is this? ______________________________
MUTATED DNA Sequence #4 ➔ T A C A C C T T G G C G A C T A C T
What is the mRNA sequence? (Circle the change)
amino acid sequence?
Will there likely be effects? What type of mutation is this? ____________________________

Answer 1

Let's break down the requested tasks based on the original DNA sequence and the mutated sequences provided.

Original DNA Sequence

• Original sequence: T A C A C C T T G G C G A C G A C T
• mRNA sequence: (transcribing the DNA to RNA, replacing Thymine (T) with Uracil (U))
  A U G U G G A A C C G C U G C U G A
• Amino acid sequence: (using the codon chart)
  AUG - Met (Methionine)
  UGG - Trp (Tryptophan)
  AAC - Asn (Asparagine)
  CGC - Arg (Arginine)
  UGC - Cys (Cysteine)
  UGA - Stop
  Amino acid sequence: Met-Trp-Asn-Arg-Cys

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Mutated DNA Sequence #1

• Mutated sequence: T A C A T C T T G G C G A C G A C T
• mRNA sequence:
  A U G U A G A A C C G C U G C U G A (Circle change: T(A) → T(A) T → A(T)*)
• Amino acid sequence:
  AUG - Met (Methionine)
  UAG - Stop
  Amino acid sequence: Met-Stop
• Likely effects: Yes, likely to be significant due to an early stop codon.
• Type of mutation: Substitution, Nonsense mutation

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Mutated DNA Sequence #2

• Mutated sequence: T A C G A C C T T G G C G A C G A C T
• mRNA sequence:
  A U G C U G G A A C C G C U G C U G A (Circle change: T(A) → G(C))
• Amino acid sequence:
  AUG - Met (Methionine)
  CUG - Leu (Leucine)
  GAA - Glu (Glutamic acid)
  CGC - Arg (Arginine)
  UGC - Cys (Cysteine)
  UGA - Stop
  Amino acid sequence: Met-Leu-Glu-Arg-Cys
• Likely effects: Yes, it likely changes the function of the protein.
• Type of mutation: Substitution, Missense mutation

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Mutated DNA Sequence #3

• Mutated sequence: T A C A C C T T A G C G A C G A C T
• mRNA sequence:
  A U G U G G A A U C G C U G C U G A (Circle change: T(T) → A(A))
• Amino acid sequence:
  AUG - Met (Methionine)
  UGG - Trp (Tryptophan)
  AAU - Asn (Asparagine)
  CGC - Arg (Arginine)
  UGC - Cys (Cysteine)
  UGA - Stop
  Amino acid sequence: Met-Trp-Asn-Arg-Cys
• Likely effects: There could be minimal effects as it’s likely a silent mutation.
• Type of mutation: Substitution, Silent mutation

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Mutated DNA Sequence #4

• Mutated sequence: T A C A C C T T G G C G A C T A C T
• mRNA sequence:
  A U G U G G A A C C G C U G A U G A (Circle change: C(G) → T(A))
• Amino acid sequence:
  AUG - Met (Methionine)
  UGG - Trp (Tryptophan)
  AAC - Asn (Asparagine)
  CGU - Arg (Arginine)
  AUC - Ile (Isoleucine)
  Stop - Codon
  Amino acid sequence: Met-Trp-Asn-Arg-Ile
• Likely effects: Yes, it causes a shift in the amino acid sequenсe.
• Type of mutation: Insertion, Frameshift mutation

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To summarize the effects and types of mutations for each of the sequences:

1. Mutation #1: Substitution, Nonsense Mutation
2. Mutation #2: Substitution, Missense Mutation
3. Mutation #3: Substitution, Silent Mutation
4. Mutation #4: Insertion, Frameshift Mutation