ANIMAL AND PLANT CELLS
- Most animal cells contain a nucleus, cytoplasm, cell membrane, mitochondria and ribosomes.
- Plant cells contain all the structures seen in aminal cells as well as a cell wall and, in many cases, chloroplasts and a permanent vacuole filled with sap.
- Enzymes control the chemical reactions inside cells.
- Cells may be specialised to carry out a particular function. Before they are specialised they are known as stem cells.
- Examples of specialised cells are fat cells, cone cells, root hair cells and sperm cells. These have may different adaptations to make them be able to do their function.
HOW DO SUBSTANCES GET IN AND OUT OF CELLS?
- Dissolved substances move in and out of cells by diffusion, osmosis and active transport.
- Diffusion is the net movement of particles from an area where they are at a high concentration to an area where they are at a low concentration.
- Osmosis is a special case of diffusion.
- Osmosis is the diffusion of water from a high water concentration to a low water concentration through a partially permeable membrane.