B3 - Protein Synthesis

Proteins are made by reading the code in DNA DNA controls the production of proteins in a cell A section of DNA that codes for a particular protein is called a gene Proteins are made up of molecules called amino acids, each protein has its own number and order of amino acids This means that each protein has a different shape and a different function It's the order of the bases which decide the order of the amino acids Each amino acid is coded for by a sequence of three bases in the gene Amino acids are joined together to make proteins by following the order of the genes Each gene contains a different sequence of bases

mRNA carries the code to the ribosomes Proteins are made in the cytoplasm by ribosomes To make the proteins the ribosomes have to use the code in DNA. DNA is found in the nucleus and cannot get out because it's really big, so the cell needs to get the code from the DNA to the ribosome This is done using mRNA, which is created by copying the code from the DNA mRNA acts as a messenger between the DNA and the ribosome, it carries the code between the two

DNA controls a cell by controlling protein production The proteins in a cell affect how it functions, some determine cell structure but others such as enzymes control cell reactions Different types of cells have different functions because they make different proteins Only certain proteins are made because only some of the full set of genes is used in any one cell. Some genes are switched off, which means the proteins they code for are not produced The genes that are switched on determine the function of the cell e.g. in a muscle cell the genes that code for muscle proteins are switched on and the genes that code for skin, nerve or bone proteins are switched off

New Page