DNA Mutations and Effects

Name:

Date:

Part 1: Identify the Mutation

Compare each changed DNA sequence with the original sequence. Choose the best answer.

1. Original: ATG CCT GAA TGG
Changed: ATG CAT GAA TGG
What type of mutation has occurred?

Substitution

Insertion

Deletion

2. Original: ATG CCT GAA TGG
Changed: ATG ACC TGA ATG G
What type of mutation has occurred?

Substitution

Insertion

Deletion

3. Original: ATG CCT GAA TGG
Changed: ATG CTG AAT GG
What type of mutation has occurred?

Substitution

Insertion

Deletion

4. Which mutation is most likely to cause a frameshift?

A substitution of one base

An insertion of one base

A substitution of three bases

Part 2: Analyse the Effects

5. In the substitution in Question 1, one DNA base has changed but the number of bases has stayed the same. Explain how this could change one amino acid in the protein.

6. Explain why an insertion or deletion of one base can affect every codon after the mutation.

7. Classify each possible effect as helpful, harmful, or neutral. Write one piece of evidence for each classification.

a) A mutation helps bacteria survive an antibiotic: ____________________

Evidence: __________________________________________________________

b) A mutation changes a codon but the same amino acid is made: ____________________

Evidence: __________________________________________________________

c) A mutation stops an important protein from working: ____________________

Evidence: __________________________________________________________

8. A mutation changes the DNA sequence, but the resulting protein and trait do not change. Is this mutation neutral? Explain your answer.

Part 3: Explain and Extend

9. Choose one mutation from this worksheet. Describe the DNA change, predict its effect on the protein, and explain whether the effect could be helpful, harmful, or neutral.

Success Criteria

Check your work:

I can identify a substitution, insertion, and deletion.

I can explain how a mutation may affect a protein.

I can classify an effect as helpful, harmful, or neutral using evidence.

Support Options

Use a ruler or reading guide to track each DNA base. Read the sequences aloud in groups of three, or ask a partner to read the questions with you. You may use a labelled diagram of DNA, codons, and proteins.

Extension Challenge

Create a new DNA sequence with one substitution, one insertion, or one deletion. Predict its effect on the protein and trait, then justify whether the effect is helpful, harmful, or neutral.