Structure of m RNA

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Structure of mRNA (Messenger RNA)

mRNA is a single-stranded RNA molecule that carries genetic information from DNA to ribosomes for protein synthesis.

1. General Features

  • Composed of ribonucleotides (A, U, G, C)

  • Single-stranded and linear

  • Has 5′ → 3′ polarity

  • Sequence is complementary to the DNA template strand

2. Structural Components of Eukaryotic mRNA

1. 5′ Cap

  • Modified 7-methyl guanosine (m⁷G) added to the 5′ end

  • Functions:

    • Protects mRNA from degradation

    • Helps ribosome binding

    • Required for nuclear export

2. 5′ Untranslated Region (5′ UTR)

  • Lies between the 5′ cap and start codon

  • Regulates translation initiation

3. Coding Region

  • Begins with start codon (AUG)

  • Ends with a stop codon (UAA, UAG, or UGA)

  • Contains codons that specify amino acids

4. 3′ Untranslated Region (3′ UTR)

  • Located after the stop codon

  • Involved in:

    • mRNA stability

    • Regulation of translation

5. Poly-A Tail

  • A stretch of adenine nucleotides (≈50–250 A’s) at the 3′ end

  • Functions:

    • Prevents degradation

    • Enhances translation

    • Aids nuclear export

3. Structure of Prokaryotic mRNA (Brief)

  • No 5′ cap

  • No poly-A tail (or very short)

  • Often polycistronic (codes for multiple proteins)

  • Contains Shine–Dalgarno sequence for ribosome binding

Diagram (Text Representation)

5′ Cap — 5′ UTR — AUG — Coding Region — Stop Codon — 3′ UTR — Poly-A Tail

If you want, I can also give a short exam answer, labeled diagram, or difference between prokaryotic and eukaryotic mRNA.

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