Gene Mutations and Proteins

Name:

Date:

📚 Part 1: Multiple Choice & Matching

Model how gene mutations affect proteins and organism function (S.8.3)

1. Which statement best defines a gene mutation?

A change in the DNA sequence

A change in the shape of a cell

A change in the number of chromosomes

2. Which type of mutation usually has the largest effect on the resulting protein?

Silent mutation

Missense (single amino acid change)

Frameshift (insertion/deletion)

Duplication of a codon

3. A nonsense mutation creates a premature stop codon. What is a likely result?

The protein is shorter and may not work

The protein has one different amino acid but is unchanged otherwise

No change to the amino acid sequence

4. Which level of protein structure is affected first when the amino acid sequence changes?

Primary structure

Tertiary structure

Quaternary structure

5. Match each mutation type (left) with the most typical effect on the protein (right).

1. Silent mutation

2. Missense mutation

3. Nonsense mutation

4. Frameshift mutation

A. Multiple amino acids changed downstream

B. Early stop codon; truncated protein

C. No change in amino acid sequence

D. Single amino acid substitution

✏️ Part 2: Short Answers & Modeling

6. Transcribe and translate the normal DNA coding strand below. Then transcribe and translate the mutated strand. Explain how the mutation changes the protein.

Normal DNA (coding strand): ATG GAA TGT

Mutated DNA (coding strand): ATG GAA TGA

Notes: Transcribe to mRNA, then translate to amino acids (use standard codons: AUG = Met, GAA = Glu, UGU = Cys, UGA = Stop).

7. Describe in one sentence how a frameshift (insertion or deletion) can affect an organism's traits.

8. Draw a simple chain showing three amino acids for the normal protein and show how a nonsense mutation (early stop) would shorten it. Label the stop point.

9. Give one real-world example of how a gene mutation can affect an organism's function or survival (briefly explain).

10. Reflection: Why is it important for scientists to model the effects of mutations on proteins?