Protein Synthesis Worksheet: Fill in DNA, mRNA, Codons & Amino ... - Free Printable

Let's go through the Protein Synthesis Worksheet step by step and explain each part. The goal is to understand how DNA is transcribed into mRNA, which is then translated into a sequence of amino acids using tRNA and the genetic code.

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🔬 Overview of the Process

1. DNA → mRNA (Transcription)
- DNA base pairing: A ↔ T, G ↔ C
- In transcription, RNA uses U instead of T

2. mRNA → Protein (Translation)
- mRNA codons (3-base sequences) are read by tRNA with complementary anti-codons
- Each codon codes for a specific amino acid (using the Codon Table)

---

## ✔ Problem 1–4 (First Sequence):

Given:
```
DNA: A T G G T A G C T A A C C T T
T A C C A T C G A T T G G A A
```

Step 1: Complementary DNA strand (already filled)

- Correctly paired:
- A ↔ T, T ↔ A, G ↔ C, C ↔ G
- So bottom strand is correct:
`T A C C A T C G A T T G G A A` ✔️

---

Step 2: Transcribe to mRNA

- mRNA is synthesized from the template strand (bottom DNA strand).
- Replace T with U in RNA.

So:
```
DNA template: T A C C A T C G A T T G G A A
mRNA: A U G G U A G C U A A C C U U
```
✔ This matches what’s written.

---

Step 3: tRNA Anti-codons

tRNA carries anti-codons that pair with mRNA codons.

| mRNA Codon | tRNA Anti-codon |
|------------|------------------|
| AUG | UAC |
| GUA | C AU |
| GCU | CGA |
| AAC | UUG |
| CUU | GAA |

But wait — the worksheet shows:
```
tRNA: U A C C A U C G A U U G G A A
```
This appears to be the same as mRNA, but it should be anti-codons.

Wait — this might be a formatting issue.

Actually, looking at the diagram:

The tRNA anti-codons are shown underneath the mRNA codons. For example:

- mRNA: A U G → tRNA: U A C → so anti-codon = UAC → pairs with AUG
- mRNA: G U A → tRNA: C A U → anti-codon = CAU → pairs with GUA
- mRNA: G C U → tRNA: C G A → anti-codon = CGA → pairs with GCU
- mRNA: A A C → tRNA: U U G → anti-codon = UUG → pairs with AAC
- mRNA: C U U → tRNA: G A A → anti-codon = GAA → pairs with CUU

✔ So yes, the tRNA anti-codons are correctly written under each mRNA codon.

---

Step 4: Amino Acids (from mRNA codons)

Use standard codon table:

| mRNA Codon | Amino Acid |
|------------|------------------|
| AUG | Methionine (Start) |
| GUA | Valine |
| GCU | Alanine |
| AAC | Asparagine |
| CUU | Leucine |

✔ These match the answers provided.

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Step 5: "mRNA is synthesized in translation or transcription?"

Answer: Transcription
➡️ mRNA is made during transcription, not translation.
Translation is when mRNA is used to build protein.

✔ Correct answer: transcription

---

Step 6: "mRNA has codons or anti-codons?"

Answer: Codons
➡️ mRNA contains codons (three-base sequences that code for amino acids).
Anti-codons are on tRNA.

✔ Correct answer: codons

---

## ✔ Problem 7–10 (Second Sequence):

Given:
```
DNA: C A G G A A T T G C T C G A T
G T C C T T A A C G A G C T A
```

Step 7: Complementary DNA strand

Already filled:
`G T C C T T A A C G A G C T A`
→ Correct based on base pairing.

---

Step 8: Transcribe to mRNA

Template strand: `G T C C T T A A C G A G C T A`
mRNA: replace T with U →
`C A G G A A U U G C U C G A U`

✔ Matches what's written.

---

Step 9: tRNA Anti-codons

Now find anti-codons for each mRNA codon:

| mRNA Codon | tRNA Anti-codon |
|------------|------------------|
| CAG | GUC |
| GAA | CUU |
| UUG | AAC |
| CUC | GAG |
| GAU | CUA |

So tRNA sequence should be:
`G U C C U U A A C G A G C U A`
(Which matches the worksheet.)

✔ Correct.

---

Step 10: Amino Acids

Use codon table:

| mRNA Codon | Amino Acid |
|------------|--------------------|
| CAG | Glutamine |
| GAA | Glutamic Acid |
| UUG | Leucine |
| CUC | Leucine |
| GAU | Aspartic Acid |

Wait — the worksheet says:

- CAG → Valine ✘ (Incorrect!)
- GAA → Glutamic Acid ✔
- UUG → Leucine ✔
- CUC → Leucine ✔
- GAU → Aspartic Acid ✔

But CAG codes for Glutamine, not Valine!

✘ Error in worksheet?

Let’s double-check:

- CAG → Glutamine (Gln)
- Valine codons: GUU, GUC, GUA, GUG

So CAG ≠ Valine

But the worksheet says:
> "Valine" under CAG → ✘ Incorrect

Also, GAA → Glutamic Acid ✔
UUG → Leucine ✔
CUC → Leucine ✔
GAU → Aspartic Acid ✔

So only first amino acid is wrong.

👉 Correction:
CAG → Glutamine, not Valine.

---

## ✔ Final Answers Summary:

Part 1–4:

- DNA complement: ✔ Correct
- mRNA: ✔ Correct
- tRNA anti-codons: ✔ Correct
- Amino acids:
- AUG → Methionine ✔
- GUA → Valine ✔
- GCU → Alanine ✔
- AAC → Asparagine ✔
- CUU → Leucine ✔

Question 5: mRNA is synthesized in transcription ✔

Question 6: mRNA has codons ✔

Part 7–10:

- DNA complement: ✔
- mRNA: ✔
- tRNA anti-codons: ✔
- Amino acids:
- CAG → Glutamine (not Valine) ✘ (Worksheet error)
- GAA → Glutamic Acid ✔
- UUG → Leucine ✔
- CUC → Leucine ✔
- GAU → Aspartic Acid ✔

---

## 🛠️ Correction Needed:
> Line 10: First amino acid should be "Glutamine", not "Valine".

---

## ✔ Final Answer Key (Corrected):

| Position | mRNA Codon | tRNA Anti-codon | Amino Acid |
|---------|------------|------------------|----------------|
| 1 | AUG | UAC | Methionine |
| 2 | GUA | CAU | Valine |
| 3 | GCU | CGA | Alanine |
| 4 | AAC | UUG | Asparagine |
| 5 | CUU | GAA | Leucine |
| 6 | CAG | GUC | Glutamine |
| 7 | GAA | CUU | Glutamic Acid |
| 8 | UUG | AAC | Leucine |
| 9 | CUC | GAG | Leucine |
| 10 | GAU | CUA | Aspartic Acid |

---

## ✔ Summary of Questions:
5. mRNA is synthesized in transcription
6. mRNA has codons

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## 💡 Conclusion:
- The worksheet is mostly correct.
- One major error: CAG codes for Glutamine, not Valine.
- This mistake could mislead students about the genetic code.

✔ Recommendation: Correct the first amino acid in section 10 from "Valine" to "Glutamine".

Let me know if you'd like a corrected version of the worksheet!