Describe the roles of DNA and RNA in determining the sequence of amino acids in proteins.

The sequence of bases (a gene) on DNA determines the order of amino acids that come together to form a polypeptide (protein) chain.

The DNA is 'unzipped' by enzymes called Helicases. This allows a single strand of DNA to be copied (transcription) to form a molecule of messenger RNA (mRNA).

The mRNA then leaves the nucleus through the nuclear pores and enters the cytoplasm.

In the cytoplasm the mRNA associates with a ribosome.

Free amino acids within the cytoplasm are brought together in the correct order (determined by the sequence of the mRNA) to form a polypeptide chain (protein).