26. Mitochondria are rodlike double membrane structures whose inner membrane folds into projections called cristae. The function of a mitochondria is to be the site of ATP synthesis and be the powerhouse of the cell.
27. Ribosomes are dense particles consisting of two subunits, each composed of ribosomal RNA and protein and they can be free or attached to the rough endoplasmic reticulum. Ribosomes function is to be the site of protein synthesis. The endoplasmic reticulum consists of a “rough” and a “smooth” portion. The rough ER is a membrane system enclosing a cavity, and coiling through the cytoplasm. It is externally studded with ribosomes and its function is to attach sugar groups to proteins and transports proteins through vesicles toward the golgi apparatus. The smooth ER is similar but it is free of ribosomes, which is why it is called smooth. The golgi apparatus is a stack of smooth membrane sacs and associated vesicles close to the nucleus. The function of the golgi
is to package, modify and segregate proteins for secretion from the cell.
28. The function of a lysosomes which is a membranous sac containing acid hydrolases is to be the site of intracellular digestion. The function of a peroxisome which is a membranous sac of oxidase enzymes is to detoxify a number of toxic substances. The most important enzyme; catalase breaks down hydrogen peroxide.