Protein Synthesis

Protein synthesis is a two-step process involving transcription and translation.
It occurs in cells and is vital for the production of proteins needed for cell structure and function.

Transcription occurs in the nucleus where the DNA unzips, and one strand is used as a template to synthesise RNA.
RNA polymerase links free RNA nucleotides together to form a strand of messenger RNA (mRNA).
Before mRNA leaves the nucleus, it undergoes splicing where introns (non-coding sequences) are removed and exons (coding sequences) are joined together.

Translation takes place at the ribosomes in the cytoplasm.
mRNA attaches itself to the ribosome where a protein is synthesised.
The sequence of bases on the mRNA determines the sequence of amino acids in the protein.
Each set of three bases (codon) on the mRNA corresponds to one amino acid.
Transfer RNA (tRNA) brings the correct amino acid to the ribosome in a process called elongation; the amino acids are joined together in a chain to form a protein.
The process stops when a stop codon is reached on the mRNA, marking the end of the protein chain.

Proteins are made up of one or more chains of amino acids, which determine their function and property.
The sequence of amino acids in a protein is determined by the sequence of bases in a gene on the DNA molecule.
The amino acid sequence determines the shape of the protein, and the shape of the protein determines its function.

Mutations in the DNA can lead to an incorrect sequence of amino acids, which can lead to the formation of faulty proteins.
DNA codes for around 20 different amino acids, which can form a wide variety of sequences to create different proteins.
Understanding protein synthesis is fundamental for understanding genetic engineering, gene therapy, and the development therapeutic drugs.