Translation

Translation

• When: After transcription, during protein synthesis.

• Where: Cytoplasm (at ribosomes; either free in cytosol or bound to ER).

Translation

From RNA to Protein

mRNA

carries codons (triplets of nucleotides) coding for amino acids.

tRNA

adaptor molecules with anticodons that bring the correct amino acids.

Ribosome

• made of rRNA + proteins; site of peptide bond formation.

Translation

Outcome: A polypeptide chain that folds into a functional protein.

Initiation

• Small ribosomal subunit binds to mRNA.

• First tRNA (carrying methionine) binds to the start codon (AUG).

• Large ribosomal subunit attaches, forming a functional ribosome.

Elongation

• tRNAs bring amino acids according to mRNA codons.

• Ribosome catalyzes peptide bonds → growing polypeptide chain.

• Ribosome moves along mRNA (5′ → 3′ direction).

Termination

• Ribosome reaches a stop codon (UAA, UAG, UGA).

• Release factor frees the polypeptide; ribosome disassembles.

Central Dogma of Molecular Biology

DNA → RNA → Protein

Replication

ensures genetic continuity.

Transcription

copies information into a mobile form (mRNA).

Translation

interprets that code into proteins — the molecules that actually perform most cell functions.