The Cells



     The cell is one of the most basic units of life.  There are millions of different types of cells.  There are cells that are organisms onto themselves, such as microscopic amoeba and bacteria cells.  And there are cells that only function when part of a larger organism, such as the cells that make up your body.  The cell is the smallest unit of life in our bodies.  In the body, there are brain cells, skin cells, liver cells, stomach cells, and the list goes on.  All of these cells have unique functions and features.  And all have some recognizable similarities.  All cells have a 'skin', called the plasma membrane, protecting it from the outside environment.  The cell membrane regulates the movement of water, nutrients and wastes into and out of the cell.  Inside of the cell membrane are the working parts of the cell.  At the center of the cell is the cell nucleus.  The cell nucleus contains the cell's DNA, the genetic code that coordinates protein synthesis.  In addition to the nucleus, there are many organelles inside of the cell - small structures that help carry out the day-to-day operations of the cell.  One important cellular organelle is the ribosome.  Ribosomes participate in protein synthesis.  The transcription phase of protein synthesis takes places in the cell nucleus.  After this step is complete, the mRNA leaves the nucleus and travels to the cell's ribosomes, where translation occurs.  Another important cellular organelle is the mitochondrion.  Mitochondria (many mitochondrion) are often referred to as the power plants of the cell because many of the reactions that produce energy take place in mitochondria.  Also important in the life of a cell are the lysosomes.  Lysosomes are organelles that contain enzymes that aid in the digestion of nutrient molecules and other materials.  Below is a labelled diagram of a cell to help you identify some of these structures.