Four other membrane-enclosed organelles that we have not looked at in detail include vacuoles, lysosomes, peroxisomes and glyoxysomes. Although vacuoles are found in animals, they are predominantly found in plant and fungal cells. The function, size and shape of vacuoles depends largely on the type of cell that we are examining. In plant cells, vacuoles function to store water, maintain hydrostatic pressure and store and hydrolyze waste products. In animal cells, vacuoles are much smaller and help in endocytotic and exocytotic processes. Lysosomes are membrane-enclosed organelles that are found in animals (recent evidence might show that they are also found in plants as well) and function to breakdown waste products and all four different types of macromolecules. They contain an acidic environment (pH of about 5) and many different types of hydrolytic enzymes that can breakdown lipids, carbohydrates, proteins and nucleic acids. Lysosomes can also destroy the cell by releasing their contents into the cytosol in a process known as autolysis. The proteins found inside lysosomes are generated in the rough endoplasmic reticulum. Microbodies, which includes peroxisomes and glyoxysomes, are spherical membrane-bound organelles. Peroxisomes are responsible for producing and breaking down hydrogen peroxide. They also contain many enzymes that can oxidize different molecules. They breakdown fatty acids to produce ATP and they can also synthesize lipids such as cholesterol. Peroxisomes are also responsible for detoxifying the cell from drugs and toxins. The proteins found inside peroxisomes are produced in free ribosomes of the cytosol part of the cell. Glyoxysomes are simply specialized peroxisomes that are found in plant and fungal cells, especially in germinating plant cells. These membrane-bound organelles are responsible for breaking down fatty acids to produce sugars that can be used by the plants before the plant actually matures and uses its chloroplast for its major source of sugars.