[♪ Music Continuing Still, Sound of the closing bell plays in the translucent screaming an Iit showing why there aren't any real The cell is the basic unit of life. Some living organisms such as animals and plants are made of hundreds of trillions of these basic units of life called cells. Animal cells. A typical animal cell will include the nucleus, a cell membrane and a cell cytoplasm. The nucleus is the structure that contains the genetic information, otherwise known as DNA, and it controls the actions and the reactions of the cell. The cell membrane, which is the border of the cell, acts as the gatekeeper and it controls what enters and exits the cell, as well as enabling neighboring cells to stick to one another. The cell cytoplasm is the site of the cell's chemical reactions. Lots of chemical reactions occur here, such as respiration. Respiration takes place in specialized structures called mitochondria. Plant cells contain the structures that animal cells contain, the nucleus, the cytoplasm and the cell membrane, but they also include lots of extra structures. For example, they contain a cell wall. A cell wall is made of cellulose, and this structure provides support for the shape of the cell. Plant cells also contain chloroplasts, which are filled with a chemical called chlorophyll. Chlorophyll enables plant cells to absorb light, so it can be used in photosynthesis. Chlorophyll is also the substance that gives plants its green colour. Finally, plant cells also contain structures known as vacuoles. These are filled with a watery substance which contains these old sugars, called cell sat. The role of the vacuole is to provide support for the cell shape and to store sugars. Specialized cells. Some cells are specialized. They are able to carry out particular jobs. The specialized cells we will look at are red blood cells, nerve cells and white blood cells. Red blood cells do not possess a nucleus. This is so that they've got enough space to be able to absorb and transport as much oxygen as possible. Nerve cells are specialized in that they have branched endings called dendrites. This is so they can communicate with lots of other nerve cells. You will also notice they have long axons along which the electrical message can travel. Finally, white blood cells enable us to fight infections. They can be identified by the characteristic lobe nucleus. White blood cells have a flexible cytoplasm so that they can engulf pathogens in a process called phagocytosis. Some other white blood cells are specialized to produce antibodies and it's these antibodies that fight pathogens.