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 mutations one by one, using the original DNA sequence you provided.

ORIGINAL DNA Sequence

DNA Sequence: T A C A C C T T G G C G A C G A C T
mRNA Sequence: A U G U G G A A C C G C U G C U G A
Amino Acid Sequence: Met - Val - Gly - Ser - Ser

MUTATED DNA Sequence #1

MUTATED DNA Sequence #1: 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 the first "A" change to "U")
Amino Acid Sequence: Met - Val - Gly - Ser - Ser

Will there likely be effects? Yes
What type of mutation is this? Substitution, Missense mutation (the first amino acid changed)

MUTATED DNA Sequence #2

MUTATED DNA Sequence #2: 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 the "A" change to "C")
Amino Acid Sequence: Met - Leu - Gly - Ser - Ser

Will there likely be effects? Yes
What type of mutation is this? Substitution, Missense mutation (the second amino acid changed)

MUTATED DNA Sequence #3

MUTATED DNA Sequence #3: 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 the "G" change to "A")
Amino Acid Sequence: Met - Val - Stop

Will there likely be effects? Yes
What type of mutation is this? Substitution, Nonsense mutation (change to stop codon)

MUTATED DNA Sequence #4

MUTATED DNA Sequence #4: 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 the "G" change to "T")
Amino Acid Sequence: Met - Val - Gly - Stop

Will there likely be effects? Yes
What type of mutation is this? Insertion, Frameshift mutation (the final position of "T" and "C" change the reading frame)

Summary

1. Mutation #1

   • Type: Substitution
   • Effect: Missense

2. Mutation #2

   • Type: Substitution
   • Effect: Missense

3. Mutation #3

   • Type: Substitution
   • Effect: Nonsense

4. Mutation #4

   • Type: Insertion
   • Effect: Frameshift