The cell membrane (or plasma Membrane) is a structure that forms the outer boundary of the cell and allows only certain materials to move into and out of the cell. Food, oxygen and water move into the cell through the membrane. Waste products also leave through the membrane. The cell wall is a rigid structure outside the cell membrane that supports and protects the cell (for plants, fungi, and some protists and bacteria). The cell wall is made of tough cellulose fibers and other materials made by the cell. Note: fungal cell walls contain chitin instead of cellulose. Chloroplasts contain a green pigment called chlorophyll. This is what makes plants green. Chloroplasts take in sunlight, water and carbon dioxide to make oxygen and sugar (a form of food). This process is called photosynthesis. Cytoplasm is the gel-like material inside the cell membrane and outside the nucleus. Cytoplasm contains a large amount of water and many chemicals and structures that carry out the life processes in the cell. These structures that the cytoplasm contains are called organelles. Unlike a gelatin dessert, however, cytoplasm constantly moves or streams. The Endoplasmic Reticulum (ER) is a folded membrane that movesmaterials around in the cell. The ER extends from the nucleus to the cell membrane and takes up quite a bit of space in some cells. The ER is like a system of conveyor belts in a business or tunnels along which materials move from one place to another. In cells, structures called Golgi Bodies (also known as Golgi apparatus or Golgi complex) are stacks of membrane- covered sacs that package and move proteins to the outside of the cell. Golgi bodies are the packaging and secreting organelles of the cell. An active cell constantly produces waste products. In thecytoplasm, organelles called lysosomes contain chemicals(enzymes) that digest wastes and worn-out cell parts. Thesechemicals also break down food. These organelles are found primarily in animal cells. Cells require a continuous supply of energy. Mitochondria are organelles where food molecules are broken down and energy is released. The energy is then stored in other molecules that can power cell reactions easily. Just as a power plant supplies energy to a business, mitochondria release energy for the cell. The largest organelle in the cytoplasm of a eukaryotic cell is usually the nucleus, a structure that directs all the activities of the cell. The nucleus is like a manager who directs everyday business for acompany and passes on information to new cells. The nucleus contains genetic blueprints for the operations of the cell known as chromatin, makes up chromosomes during interphase of cell division. Nuclear envelope (or nuclear membrane) has pores in the membrane that allows materials to move in and out of the nucleus. The nucleolus is a region in the nucleus, ball-shaped, where ribosome are made. One chemical that takes part in nearly every cell activity is protein. Proteins are needed for chemical reactions that take place in the cytoplasm. Cells make their own proteins on small structures in the cytoplasm called ribosomes. Remember the last vacation you took? Your suitcase temporarily stored your clothes. Within a cell, a vacuole fills a similar role as a temporary storage space for the cell. Centrioles are found in the animal cell. They are used during cell division to divide chromosomes. Vacuoles store water, food, pigments, waste or other materials. Vacuoles are large in plant cells and small in animal cells. Vacuoles can also be found in fungi and protists. Just like a taxi transports people, vesicles transport protein packages created by the Golgi bodies. Chloroplast is chlorophyll-containing organelles where photosynthesis takes place in plants. Light energy is transformed into chemical energy.
