Amoeba Sisters Video Recap worksheet on mutations, featuring educational content and illustrations about genetic changes in DNA.

Let's go through the Amoeba Sisters Video Recap: Mutations (Updated) worksheet step by step, solving each question and explaining the reasoning.

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1. What is a mutation?

✔ Answer:
A mutation is a change in genetic material. It is specifically a change within a nucleic acid. That includes fungi, protists, plants, bacteria, archaea, animals, and viruses.

🔹 Explanation:
Mutations are alterations in the DNA or RNA sequence of an organism. These changes can occur naturally or due to environmental factors like radiation or chemicals. Since all living organisms (and some viruses) have genetic material made of nucleic acids, mutations can happen across all domains of life.

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2. A specific part of a nucleic acid (such as DNA or RNA) experiences a mutation that could lead to a different protein produced. View the illustration below of DNA. Which part of the DNA experiences the mutation?

✔ Answer:
Nitrogenous Bases

🔹 Explanation:
DNA consists of sugar-phosphate backbones and nitrogenous bases (adenine, thymine, cytosine, guanine). The sequence of these nitrogenous bases determines the genetic code. A mutation occurs when one of these bases is changed (e.g., via substitution, insertion, or deletion), potentially altering the amino acid sequence during protein synthesis.

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3. On the DNA illustration, draw an arrow to show where the answer to #2 could be located.

✔ Answer:
(You would draw an arrow pointing to one of the colored circles representing the nitrogenous bases on the DNA strand.)

🔹 Explanation:
In the cartoon image, the colorful circles along the DNA helix represent the nitrogenous bases. You should point to any of those bases — for example, the blue, purple, yellow, or orange circle — since it's the base that mutates.

> 📝 *Note: This is a visual task; you cannot draw here, but in the original worksheet, you’d draw an arrow to a nitrogenous base.*

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4. The mRNA codon CUU could mutate to C__CU and still code for leucine, which would not change the amino acid.

✔ Answer:
CUC

🔹 Explanation:
The mRNA codon CUU codes for the amino acid leucine. Because of the degeneracy of the genetic code, multiple codons can code for the same amino acid.

- CUU, CUC, CUA, and CUG all code for leucine.
- So if CUU mutates to CUC, it’s still leucine → this is a silent mutation.

So, the blank should be filled with: CUC

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5. Which type(s) of organism(s) can experience a mutation? Mark any that apply.

✔ Answers (all checked):
- ☑ Animals (this includes humans)
- ☑ Archaea
- ☑ Bacteria
- ☑ Fungi
- ☑ Plants
- ☑ Protists

🔹 Explanation:
All living organisms contain DNA (or RNA in some viruses) and undergo replication, so they can experience mutations. Even single-celled organisms like bacteria and protists can have mutations. Viruses are not listed here, but many of these organisms host viruses that also mutate.

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6. Even a gene mutation that is a point mutation, meaning it affects one nucleotide base, can still make a major change.

#### Scenario: Sickle Cell Anemia

We're given:
- Normal hemoglobin DNA: GGA CTC CTC
- mRNA: CCU GAG GAG
- Amino Acids: Proline – Glutamic Acid – Glutamic Acid

Now, suppose there's a point mutation: the first T (thymine) in the second codon (CTC) is replaced by an A (adenine) → becomes CAC.

Let’s analyze:

#### Mutated DNA:
Original: `GGA CTC CTC`
Mutated: `GGA CAC CTC`

#### mRNA:
- Transcribe DNA to mRNA (remember: mRNA is complementary and uses U instead of T):
- GGA → CCU
- CAC → GUG
- CTC → GAG

So, mutated mRNA: CCU GUG GAG

#### Amino Acids:
Use the codon chart:
- CCU → Proline
- GUG → Valine
- GAG → Glutamic Acid

So, amino acid sequence: Proline – Valine – Glutamic Acid

➡️ This is the sickle cell mutation!

✔ Final Answers for Question 6:

- Portion of mutated hemoglobin DNA: GGA CAC CTC
- mRNA: CCU GUG GAG
- Amino Acids: Proline – Valine – Glutamic Acid

🔹 Explanation:
This is a substitution mutation (T → A), which changes the codon from CTC (glutamic acid) to CAC (valine). This single amino acid change alters the shape of hemoglobin, causing red blood cells to become sickle-shaped under low oxygen. This is a classic example of how a point mutation can cause a major disease.

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✔ Summary of Key Concepts:

| Concept | Explanation |
|--------|-------------|
| Mutation | Change in nucleic acid sequence |
| Silent Mutation | Changes DNA but not amino acid (e.g., CUU → CUC) |
| Point Mutation | One base changed (can be silent, missense, or nonsense) |
| Sickle Cell Anemia | Caused by a point mutation changing glutamic acid to valine |

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🌟 Final Answer Boxed:

> Question 4: CUC
> Question 6:
> - Mutated DNA: GGA CAC CTC
> - mRNA: CCU GUG GAG
> - Amino Acids: Proline – Valine – Glutamic Acid

This mutation demonstrates how a single nucleotide change can have profound effects on health and protein function.

Let me know if you'd like a printable version or help drawing the arrow!