Protein Synthesis

Transcription occurs…

In the nucleus.

Transcription 1

RNA polymerase binds to the DNA base sequence of a gene.

Transcription 2

Enzyme unwinds and exposes part of the D NA molecule.

Transcription 3

RNA polymerase moves along one strand of the exposed gene and catalyzes synthesis of an mRNA, whose nucleotides are complementary to those of the strand of the gene.

Transcription 4

When RNA polymerase reaches the end of the gene, the newly formed mR NA is released.

Transcription 5

The DNA rewinds and closes the double helix.

Transcription 6

The mRNA passes through a pore in the nuclear envelope and enters the cytoplasm.

Translation occurs… 

In the cytoplasm.

Translation 1

A ribosome binds to the mRNA near the codon at the beginning of the messenger strand.

Translation 2

A tRNA molecule that has the complementary anticodon brings its amino acid to the ribosome.

Translation 3

A second tRNA brings the next amino acid to the ribosome.

Translation 4

A peptide bond forms between the two amino acids, and the first tRNA is released.

Translation 5

This process repeats for each codon in the mRNA sequence as the ribosome moves along its length, forming a chain of amino acids.

Translation 6

The growing amino acid chain folds into the unique conformation of a functional protein.

Translation 7

The completed protein molecule is released. The mRNA, ribosome, and tRNA are recycled.