Transcription and Translation Worksheet Diagram

Let's solve this step-by-step based on the diagram and the instructions provided.

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Part (a): Label the Diagram

We are given a word list to label parts of the diagram showing transcription (top) and translation (bottom). The diagram has two main sections:

- Top: Transcription in the nucleus.
- Bottom: Translation in the cytoplasm.

We'll go through each numbered label and identify what it refers to.

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#### Top Section: Transcription

This is occurring in the nucleus, where DNA is used to make mRNA.

1. Label 1: This is a strand of RNA being synthesized from the DNA template. It’s complementary to the DNA template strand.
→ mRNA (transcription)

2. Label 2: This enzyme synthesizes RNA using DNA as a template.
→ RNA polymerase

3. Label 3: This is a segment of DNA that serves as the template for mRNA synthesis. It runs in the 3' to 5' direction.
→ DNA - template strand

4. Label 4: The structure that surrounds the nucleus and separates it from the cytoplasm.
→ nuclear membrane

5. Label 5: The double helix of DNA, with one strand serving as the template. The strand not being used as a template is called the coding strand because its sequence matches the mRNA (except T instead of U).
→ DNA - coding strand

6. Label A: This is the entire process happening in the nucleus — copying DNA into RNA.
→ transcription

7. Label B: This arrow shows the movement of mRNA from the nucleus to the cytoplasm.
→ mRNA (transcription) → But since it's moving out, we can label B as mRNA (transcription) or just mRNA. However, more precisely, it's the mRNA molecule leaving the nucleus.
→ mRNA (transcription)

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#### Bottom Section: Translation

This occurs in the cytoplasm, where mRNA is read by ribosomes to build a protein.

6. Label 6: The large structure where translation occurs.
→ ribosome

7. Label 7: The RNA strand being read by the ribosome. It carries the genetic code from DNA.
→ mRNA (translation)

8. Label 8: The small cloverleaf-shaped RNA molecules carrying amino acids. Each has an anticodon that pairs with the mRNA codon.
→ tRNA with amino acid

9. Label 9: The three-letter code on mRNA that specifies an amino acid. Example: AUG codes for Methionine.
→ codon

10. Label 10: The growing chain of amino acids linked together.
→ peptide

11. Label 11: The three-base sequence on tRNA that pairs with the mRNA codon.
→ anticodon

12. Label 12: The amino acid attached to the tRNA.
→ amino acid

13. Label 13: Another tRNA molecule that has not yet picked up an amino acid.
→ tRNA without amino acid

14. Label C: The entire process occurring in the cytoplasm — building a protein from mRNA.
→ translation

15. Label D: The direction of protein synthesis (from N-terminus to C-terminus), which corresponds to the reading of mRNA from 5' to 3'.
→ translation

Also, note the 5’ and 3’ ends must be labeled for all DNA and RNA strands.

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Part (b): Label the 5′ and 3′ ends

We need to label the 5′ and 3′ ends of all DNA and RNA strands.

#### Top (Transcription):
- The DNA template strand runs 3′ → 5′ (because RNA polymerase reads it in this direction).
- The DNA coding strand runs 5′ → 3′ (same as mRNA, except T instead of U).
- The mRNA is synthesized 5′ → 3′, so:
- mRNA 5′ end is at the left (start of transcription)
- mRNA 3′ end is at the right (end of transcription)

So:
- On the mRNA strand (label 1):
- Left end = 5′
- Right end = 3′
(Already labeled)

- On the DNA template strand (label 3):
- Left end = 3′
- Right end = 5′

- On the DNA coding strand (label 5):
- Left end = 5′
- Right end = 3′

#### Bottom (Translation):
- The mRNA strand (label 7) runs 5′ → 3′ from left to right.
- So, 5′ end is on the left, 3′ end is on the right

- The tRNA molecules have their anticodon loops facing the mRNA. The tRNA enters the ribosome with the amino acid at the 3′ end.

But the 5′ and 3′ ends of tRNA are not directly labeled here, but the mRNA is clearly oriented.

So, label:
- mRNA (label 7):
- Left end = 5′
- Right end = 3′

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✔ Final Answers:

#### (a) Labels:

| Number | Label |
|--------|-------|
| 1 | mRNA (transcription) |
| 2 | RNA polymerase |
| 3 | DNA - template strand |
| 4 | nuclear membrane |
| 5 | DNA - coding strand |
| 6 | ribosome |
| 7 | mRNA (translation) |
| 8 | tRNA with amino acid |
| 9 | codon |
| 10 | peptide |
| 11 | anticodon |
| 12 | amino acid |
| 13 | tRNA without amino acid |
| A | transcription |
| B | mRNA (transcription) |
| C | translation |
| D | translation |

> Note: A, B, C, D are boxes on the side indicating processes or molecules.

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#### (b) 5′ and 3′ Ends:

- DNA template strand (label 3):
- Left end = 3′
- Right end = 5′

- DNA coding strand (label 5):
- Left end = 5′
- Right end = 3′

- mRNA (label 1 and 7):
- Left end = 5′
- Right end = 3′

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🔍 Explanation:

- Transcription occurs in the nucleus, where RNA polymerase uses the template strand of DNA (3′→5′) to synthesize mRNA (5′→3′). The coding strand is identical to mRNA (T→U).
- Translation occurs in the cytoplasm on ribosomes. The mRNA is read in the 5′→3′ direction. tRNA brings amino acids to the ribosome via anticodon-codon pairing. The peptide bond forms between amino acids, forming a peptide chain.
- Codons are on mRNA; anticodons are on tRNA.
- The nuclear membrane separates transcription and translation (in eukaryotes).

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✔ All labels and directions are now correctly assigned!