Animal cell. Illustration showing the organelles present in an animal cell. At lower centre is the nucleus,which contains the cell's genetic information in the form of DNA (deoxyribonucleic acid). Surrounding the nucleus is endoplasmic reticulum (ER,above nucleus),a membrane bound organelle that is the site of lipid synthesis and the production of membrane-bound proteins. ER may be either rough (RER),that is with ribosomes (black dots),or smooth (SER),without ribosomes. Also seen are mitochondria (oval),which produce the cell's energy,and Golgi apparatus (bottom centre),a membrane-bound organelle that modifies and packages proteins. The round structures are lysosomes,which contain enzymes for digesting foreign particles |