mRNA
AccessExcellence 

Links
Protein Synthesis**
Codons - 20 amino acids 
Synthesis***

DNA - deoxyribonucleic acid

	found in the nucleus
	controls the function and structures of the cell
	genes are segments of DNA
	each gene controls the synthesis of one protein (generally)
	proteins are composed of amino acids arranged in specific sequences - polypeptide chains
	each amino acid is synthesised by a set of three nucleotides called a codon

1. DNA "unzips" - a segment of the double helix uncoils and separates to allow mRNA to be formed
2. mRNA leaves the nucleus
3. mRNA attaches to a ribosome on the endoplasmic reticulum
4. each tRNA segment brings a specific amino acid (present in the cytoplasm) to the mRNA
   • each tRNA can only link with a specific amino acid
5. when all of the sites on the mRNA are occupied by complementary segments of RNA, the protein folds to form its specific characteristic shape
6. some proteins need to go to the Golgi apparatus to complete their synthesis

	some proteins are exported as enzymes, hormones, etc
	some proteins are necessary for the cell's function
	some are used to produce membranes or the structures on membranes