Controlling gene expression

• All the cells in an organism carry the same gene but the structure and function of sdifferent cells varies
• Structure and function varies because not all the genes in a cell are expressed (transcribed and used to make a functional protein)
• Some genes in a cell are selectively switched on and off
• Because cells show different gene expression, different proteins are made and these proteins modify the cell - they determine the cell structure and controll cell processes (including the expression of more genes which produces more proteins)
• Gene expression (protein synthesis) can be controlled at the transcriptional, post-transcriptional, and post-translational level