[Music] hi and welcome back to free science lessons by the end of this video you should be able to describe the structure and function of the vacuoles found in animal and plant cells over the last few videos we've been looking at the organelles found in eukaryotic cells one of the key features of cells is that they're dynamic organelles can move around and increase or decrease in number depending on what the cell is doing now a good example of this are vesicles vesicles are simply sacks of fluid and caused by a membrane and we've already seen examples of vesicles for example vesicles transfer proteins from the rough endoplasmic reticulum to the Golgi apparatus in the Golgi apparatus carbohydrate molecules can be attached to the proteins to form glycol proteins vesicles then carry the glycol proteins from the Golgi apparatus to the cell membrane to be secreted from the cell now sometimes cells form membrane sacs which are larger than a vesicle and can be longer lived in this case scientists call this a vacuole and a good example of this is in phagocytosis during phagocytosis pathogens are engulfed by a white blood cell in this case the pathogen is contained in a phagocytic vacuole lysosomes then fuse with the phagocytic vacuole and the lysosomal enzymes destroy the pathogen vacuoles play other roles in animal cells for example in the removal of waste materials now a key idea you need to understand is that animal cell vacuoles are temporary structures however in plant cells we find a large permanent vacuole a plant cell vacuole is surrounded by a membrane called the tonoplast the tonoplast plays a role in control in which chemicals enter and leave the vacuole the fluid in the vacuole is called the cell sap cell sap contains dissolved sugars mineral salts and amino acids the cell sub can also contain other molecules for example in some plants the cell sap contains poisonous chemicals to deter herbivores whereas in flowers the cell sap can contain colored pigments to attract pollinators the cell sub can also contain waste chemicals produced by the plant cell now the vacuole plays another very important role in plant cells as we've seen the cell sap contains dissolved chemicals including mineral salts and because of this the cell sap has a low water potential this means that water moves into the plant cell by osmosis and this water enters the vacuole this creates a hydrostatic pressure acting outwards and this causes the cytoplasm to press against the cellulose cell wall scientists say that the plant cell is turgid and the turgidity of the plant cells helps to support the plant this is very important for plants which do not have a woody stem okay so hopefully now you can describe the structure and function of the vacuoles found in animal and plant cells [Music]