DNA Transcription and Translation Activity (Middle School and Up) - Free Printable

Let’s solve this step by step.

We are given DNA sequences for three organisms. We need to:

1. Transcribe DNA → mRNA (remember: A→U, T→A, C→G, G→C)
2. Translate mRNA → tRNA codons (tRNA is complementary to mRNA — so A↔U, C↔G)
3. Use the genetic code to find which amino acid each mRNA codon codes for.

⚠️ Important note: The worksheet says “tRNA Codons” but in biology, tRNA has *anticodons* that pair with mRNA codons. So we’ll treat “tRNA Codons” as the anticodon sequence that matches the mRNA.

Also, remember: DNA is read 3’ to 5’, and mRNA is made 5’ to 3’. But since the problem gives us short triplets without direction, we’ll assume they’re written 5’ to 3’ for simplicity (as is common in worksheets like this).

---

Step 1: Understand base pairing

DNA → mRNA transcription:
- DNA A → mRNA U
- DNA T → mRNA A
- DNA C → mRNA G
- DNA G → mRNA C

mRNA → tRNA anticodon:
- mRNA A → tRNA U
- mRNA U → tRNA A
- mRNA C → tRNA G
- mRNA G → tRNA C

Then use standard genetic code table to get amino acids from mRNA codons.

---

## Organism 1:

DNA:
AAA → mRNA: UUU → tRNA: AAA → Amino Acid: Phenylalanine (Phe)
UCG → mRNA: AGC → tRNA: UCG → Amino Acid: Serine (Ser)
ATG → mRNA: UAC → tRNA: AUG → Amino Acid: Tyrosine (Tyr)
TGG → mRNA: ACC → tRNA: UGG → Amino Acid: Threonine (Thr)

Wait — let me double-check ATG:

DNA: A T G
mRNA: U A C (because A→U, T→A, G→C) → yes
tRNA anticodon: A U G (complement of UAC) → yes
Amino acid for UAC = Tyrosine → correct.

TGG:
DNA: T G G
mRNA: A C C
tRNA: U G G
ACC → Threonine → correct.

---

## Organism 2:

DNA:
CAC → mRNA: GUG → tRNA: CAC → Valine (Val)
AAA → mRNA: UUU → tRNA: AAA → Phenylalanine (Phe)
ACA → mRNA: UGU → tRNA: ACA → Cysteine (Cys)
ATG → mRNA: UAC → tRNA: AUG → Tyrosine (Tyr)
ATA → mRNA: UAU → tRNA: AUA → Tyrosine (Tyr)
TTA → mRNA: AAU → tRNA: UUA → Asparagine (Asn)
GTA → mRNA: CAU → tRNA: GUA → Histidine (His)
TTC → mRNA: AAG → tRNA: UUC → Lysine (Lys)
TCC → mRNA: AGG → tRNA: UCC → Arginine (Arg)

Check one: GTA → DNA G T A → mRNA C A U → tRNA G U A → CAU = His → correct.

TTC → DNA T T C → mRNA A A G → tRNA U U C → AAG = Lys → correct.

TCC → DNA T C C → mRNA A G G → tRNA U C C → AGG = Arg → correct.

---

## Organism 3:

DNA:
ATA → mRNA: UAU → tRNA: AUA → Tyrosine (Tyr)
TTA → mRNA: AAU → tRNA: UUA → Asparagine (Asn)
AAA → mRNA: UUU → tRNA: AAA → Phenylalanine (Phe)
ATG → mRNA: UAC → tRNA: AUG → Tyrosine (Tyr)
TTC → mRNA: AAG → tRNA: UUC → Lysine (Lys)
ACA → mRNA: UGU → tRNA: ACA → Cysteine (Cys)
TCC → mRNA: AGG → tRNA: UCC → Arginine (Arg)
GTA → mRNA: CAU → tRNA: GUA → Histidine (His)

All match previous patterns.

---

Now let’s write out the full answers clearly.

Final Answer:

Organism 1:
DNA: AAA → mRNA: UUU → tRNA: AAA → Amino Acid: Phe
DNA: UCG → mRNA: AGC → tRNA: UCG → Amino Acid: Ser
DNA: ATG → mRNA: UAC → tRNA: AUG → Amino Acid: Tyr
DNA: TGG → mRNA: ACC → tRNA: UGG → Amino Acid: Thr

Organism 2:
DNA: CAC → mRNA: GUG → tRNA: CAC → Amino Acid: Val
DNA: AAA → mRNA: UUU → tRNA: AAA → Amino Acid: Phe
DNA: ACA → mRNA: UGU → tRNA: ACA → Amino Acid: Cys
DNA: ATG → mRNA: UAC → tRNA: AUG → Amino Acid: Tyr
DNA: ATA → mRNA: UAU → tRNA: AUA → Amino Acid: Tyr
DNA: TTA → mRNA: AAU → tRNA: UUA → Amino Acid: Asn
DNA: GTA → mRNA: CAU → tRNA: GUA → Amino Acid: His
DNA: TTC → mRNA: AAG → tRNA: UUC → Amino Acid: Lys
DNA: TCC → mRNA: AGG → tRNA: UCC → Amino Acid: Arg

Organism 3:
DNA: ATA → mRNA: UAU → tRNA: AUA → Amino Acid: Tyr
DNA: TTA → mRNA: AAU → tRNA: UUA → Amino Acid: Asn
DNA: AAA → mRNA: UUU → tRNA: AAA → Amino Acid: Phe
DNA: ATG → mRNA: UAC → tRNA: AUG → Amino Acid: Tyr
DNA: TTC → mRNA: AAG → tRNA: UUC → Amino Acid: Lys
DNA: ACA → mRNA: UGU → tRNA: ACA → Amino Acid: Cys
DNA: TCC → mRNA: AGG → tRNA: UCC → Amino Acid: Arg
DNA: GTA → mRNA: CAU → tRNA: GUA → Amino Acid: His