Protein Synthesis Worksheet - BIO 1150 - Studocu - Free Printable

Let's go through the Protein Synthesis Worksheet step by step and correct or verify each part based on molecular biology principles. We'll address the tasks in order, explain the reasoning, and clarify any errors.

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Problem 1: Fill in the complementary DNA strand

Given DNA strand (top):
A T G G T A G C T A A C C T T

We need to find the complementary DNA strand using base pairing rules:

- A ↔ T
- T ↔ A
- G ↔ C
- C ↔ G

So, complement of:
```
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
```

✔ The student has written:
T A C C A T C G A T T G G A A → This is correct.

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Problem 2: Transcribe mRNA from the bottom DNA strand

The bottom DNA strand is:
T A C C A T C G A T T G G A A

mRNA is synthesized from this template strand via transcription, with RNA bases replacing DNA bases:

- A ↔ U (in RNA)
- T ↔ A
- G ↔ C
- C ↔ G

So, transcribe DNA → mRNA:

```
DNA: 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
```

✔ Student wrote: A U G G U A G C U A A C C U U → Correct

> Note: The red mark near "GUA" seems like a correction attempt, but it’s actually correct.

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Problem 3: tRNA anti-codons

tRNA carries the anti-codon, which is complementary to the mRNA codon.

For each mRNA codon:

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

So the tRNA anti-codons should be:
UAC CUG CGA UUG GAA

✔ Student wrote: U A C C A U C G A U U G G A A — Wait! That’s not anti-codons.

This appears to be a mistake.

The student wrote the same sequence as mRNA, but tRNA anti-codons must be complementary to mRNA codons.

So correct tRNA anti-codons are:

| mRNA | AUG | GUA | GCU | AAC | CUU |
|------|-----|-----|-----|-----|-----|
| tRNA | UAC | CUG | CGA | UUG | GAA |

So line 3 should be:
U A C C U G C G A U U G G A A

✘ Student wrote: U A C C A U C G A U U G G A A → This looks like they copied the mRNA again, not anti-codons.

⚠️ Error here: tRNA anti-codons must be complementary to mRNA codons.

---

Problem 4: Amino Acids

Now use the mRNA codons and codon table to determine amino acids.

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

✔ Student wrote:
- Methionine
- Valine
- Alanine
- Asparagine
- Leucine

→ All correct.

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Problem 5: mRNA is synthesized in translation or transcription?

Answer: Transcription

✔ Student circled transcription → Correct

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Problem 6: mRNA has codons or anti-codons?

mRNA has codons (three-base sequences that code for amino acids).

tRNA has anti-codons.

✔ Student circled codons → Correct

---

Section 7–10: Second DNA Sequence

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

Complement (bottom strand):
We need to fill in the complementary DNA strand.

```
DNA: C A G G A A T G C T C G A T
↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓
G T C C T T A C G A G C T A
```

✔ Student wrote: G T C C T T A C G A G C T A → Correct

---

Problem 8: mRNA transcription

Template DNA: G T C C T T A C G A G C T A

Transcribe to mRNA:

- G → C
- T → A
- C → G
- C → G
- T → A
- T → A
- A → U
- C → G
- G → C
- A → U
- G → C
- C → G
- T → A
- A → U

So mRNA:
C A G G A A U G C U C G A U

✔ Student wrote: C A G G A A U G C U C G A U → Correct

---

Problem 9: tRNA anti-codons

Now, for each mRNA codon, write the tRNA anti-codon (complementary):

| mRNA | CAG | GAA | UGC | UCG | AU |
|------|-----|-----|-----|-----|----|
| tRNA | GUC | CUU | ACG | AGC | UA |

Wait — last codon is AU, but that’s only two bases. Let's check:

mRNA: C A G G A A U G C U C G A U

Break into codons:
- CAG
- GAA
- UGC
- UCG
- AU → incomplete?

Wait — the DNA was: C A G G A A T G C T C G A T → 14 bases → 14/3 = 4.66 → Not divisible by 3

But let's count:

C A G G A A T G C T C G A T → 14 nucleotides

That’s odd — protein synthesis usually works in triplets. But perhaps we’re missing something.

Wait — look at the original DNA:

C A G G A A T G C T C G A T

That’s 14 bases → so maybe it's meant to be:

CAG GAA TGC TCG AT → still ends at AT, which is incomplete.

But the student wrote mRNA: C A G G A A U G C U C G A U → 14 bases.

And tRNA: G U C C U U A C G A G C C U A

Wait — student wrote: G U C C U U A C G A G C C U A

Let’s analyze:

mRNA: C A G G A A U G C U C G A U
Codons: CAG, GAA, UGC, UCG, AU → last one is incomplete.

But student wrote tRNA: GUC CUU ACG AGC CUA → 5 codons, 15 bases? No — let's see:

Student wrote: G U C C U U A C G A G C C U A → 14 bases.

So matching:

| mRNA | CAG | GAA | UGC | UCG | AU |
|------|-----|-----|-----|-----|----|
| tRNA | GUC | CUU | ACG | AGC | UA |

But AU is not a valid codon. It should be AUG or AU... — likely typo.

Wait — original DNA: C A G G A A T G C T C G A T

Let’s re-express properly:

- CAG → mRNA: CAG → tRNA: GUC → Glutamine
- GAA → mRNA: GAA → tRNA: CUU → Glutamic acid
- TGC → mRNA: UGC → tRNA: ACG → Cysteine
- TCG → mRNA: UCG → tRNA: AGC → Serine
- AT → mRNA: AU → incomplete

Ah! There’s a problem: AT is only two bases. But DNA has 14 bases — probably a typo.

Wait — the DNA is written as:

C A G G A A T G C T C G A T

That’s 14 bases: positions 1–14

But codons are read in groups of three.

So:
1–3: CAG
4–6: GAA
7–9: TGC
10–12: TCG
13–14: AT → incomplete

But student wrote mRNA: C A G G A A U G C U C G A U → 14 bases

And tRNA: G U C C U U A C G A G C C U A → 14 bases

So they seem to have paired:

- CAG → GUC (anti-codon)
- GAA → CUU
- UGC → ACG
- UCG → AGC
- AU → UA? But AU isn’t a codon.

Wait — last two bases are A and U, but in mRNA, after UCG comes A U, but it should be AUG or AU... — unless the last codon is AUG?

Wait — the DNA ends with A T → so mRNA ends with A U

But that can't form a complete codon.

Possibility: the DNA might be intended as:

C A G G A A T G C T C G A T

But if we group:

- CAG
- GAA
- TGC
- TCG
- AT → incomplete

So either:
- It's a mistake in the worksheet
- Or the last two bases are meant to be A T, and we ignore them?

But student wrote mRNA: C A G G A A U G C U C G A U

Which is:
- CAG
- GAA
- UGC
- UCG
- AU → invalid

But student wrote tRNA: G U C C U U A C G A G C C U A

Which is:
- GUC (anti-CAG)
- CUU (anti-GAA)
- ACG (anti-UGC)
- AGC (anti-UCG)
- CUA (anti-AUG?) — but mRNA has AU, not AUG

Wait — if mRNA ends with A U, then tRNA would have U A, but student wrote C U A — that suggests they thought mRNA had AUG?

But DNA ends with A T, so mRNA ends with A U — no G.

So there’s a discrepancy.

Wait — look back: DNA is written as:

C A G G A A T G C T C G A T

But the student wrote the complementary strand as:

G T C C T T A C G A G C T A

Let’s check:

- C → G
- A → T
- G → C
- G → C
- A → T
- A → T
- T → A
- G → C
- C → G
- T → A
- C → G
- G → C
- A → T
- T → A

So complementary DNA: G T C C T T A C G A G C T A

Now, template strand for transcription is this bottom strand:
G T C C T T A C G A G C T A

So mRNA is transcribed from this:

- G → C
- T → A
- C → G
- C → G
- T → A
- T → A
- A → U
- C → G
- G → C
- A → U
- G → C
- C → G
- T → A
- A → U

So mRNA: C A G G A A U G C U C G A U

Same as student.

Now, break into codons:
- CAG → Glutamine
- GAA → Glutamic acid
- UGC → Cysteine
- UCG → Serine
- AU → incomplete

But student wrote amino acids:
- Glutamine
- Glutamic acid
- Leucine
- Leucine
- Aspartic acid

Wait — Leucine? But UGC codes for Cysteine, UCG codes for Serine, not Leucine.

✘ Mistake here!

Let’s check:

| mRNA Codon | Amino Acid |
|------------|------------|
| CAG | Glutamine ✔ |
| GAA | Glutamic acid ✔ |
| UGC | Cysteine ✘ (student said Leucine) |
| UCG | Serine ✘ (student said Leucine) |
| AU | Incomplete |

So student wrote:
- Glutamine ✔
- Glutamic acid ✔
- Leucine ✘ (should be Cysteine)
- Leucine ✘ (should be Serine)
- Aspartic acid ✘ (no codon)

Also, last codon is AU, not GAU or anything.

But student wrote Aspartic acid, which corresponds to GAU, but mRNA has AU, not GAU.

So clearly, errors in amino acids.

Let’s correct:

Correct Amino Acids for mRNA: CAG GAA UGC UCG AU

- CAG → Glutamine
- GAA → Glutamic acid
- UGC → Cysteine
- UCG → Serine
- AU → incomplete

But since it’s not a full codon, we ignore it.

So amino acids should be:
1. Glutamine
2. Glutamic acid
3. Cysteine
4. Serine

But student wrote:
- Glutamine ✔
- Glutamic acid ✔
- Leucine ✘
- Leucine ✘
- Aspartic acid ✘

So major error in amino acids.

Also, tRNA anti-codons:

- CAG → GUC
- GAA → CUU
- UGC → ACG
- UCG → AGC
- AU → UA (but incomplete)

Student wrote: G U C C U U A C G A G C C U A

Which is:
- GUC → anti-CAG ✔
- CUU → anti-GAA ✔
- ACG → anti-UGC ✔
- AGC → anti-UCG ✔
- CUA → anti-AUG? But mRNA has AU, not AUG

So student likely assumed the last codon was AUG, but it's not.

Unless the DNA was meant to be longer.

Wait — look at the DNA: C A G G A A T G C T C G A T

But T G C T C G A T — maybe it's TGC TCG AT — but AT is not a codon.

Perhaps the DNA is:

C A G G A A T G C T C G A T

But if we read it as:
- CAG
- GAA
- TGC
- TCG
- AT → incomplete

But TGC → mRNA: UGC → Cysteine
TCG → mRNA: UCG → Serine

So yes, student incorrectly assigned Leucine to both.

Leucine codons are: UUA, UUG, CUU, CUC, CUA, CUG

So UGC and UCG are not leucine.

✔ Correct amino acids:
- Glutamine
- Glutamic acid
- Cysteine
- Serine

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Summary of Errors:

1. tRNA anti-codons in first section: Student wrote mRNA again instead of anti-codons.
- Should be: UAC CUG CGA UUG GAA
- Not: UACCAUCGAUU GGAA

2. Amino acids in second section:
- UGC → Cysteine, not Leucine
- UCG → Serine, not Leucine
- Last codon incomplete

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Final Corrections:

#### Section 1:
- tRNA (line 3): U A C C U G C G A U U G G A A
- Amino Acids (line 4): All correct ✔

#### Section 2:
- tRNA (line 9): G U C C U U A C G A G C ? (last incomplete)
- Amino Acids (line 10):
- Glutamine ✔
- Glutamic acid ✔
- Cysteine ✘ (not Leucine)
- Serine ✘ (not Leucine)
- (Incomplete)

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Answers to Questions:

5. mRNA is synthesized in transcription → ✔
6. mRNA has codons → ✔

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✔ Final Corrected Worksheet:

#### First Set:
1. DNA:
Top: A T G G T A G C T A A C C T T
Bottom: T A C C A T C G A T T G G A A

2. mRNA: A U G G U A G C U A A C C U U

3. tRNA: U A C C U G C G A U U G G A A
*(Complementary to mRNA)*

4. Amino Acids:
- Methionine
- Valine
- Alanine
- Asparagine
- Leucine → ✔

5. mRNA is synthesized in transcription → ✔
6. mRNA has codons → ✔

#### Second Set:
7. DNA:
Top: C A G G A A T G C T C G A T
Bottom: G T C C T T A C G A G C T A

8. mRNA: C A G G A A U G C U C G A U

9. tRNA: G U C C U U A C G A G C U A (last incomplete)

10. Amino Acids:
- Glutamine
- Glutamic acid
- Cysteine
- Serine
- (Incomplete)

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Key Takeaways:

- tRNA anti-codons are complementary to mRNA codons.
- Always use the codon table correctly.
- Check for triplet grouping and ensure codons are complete.
- mRNA has codons, tRNA has anti-codons.
- Transcription makes mRNA; Translation makes protein.

Let me know if you'd like a printable corrected version!