Damn Near Everything There Is To Know About Cells: Essay -- essays res

Damn Near Everything There Is To Know About Cells: Biology Cell Report There are many parts of a cell, they all have specific duties, and are all needed to continue the life of the cell. Some cells exist as single-celled organisms that perform all of the organism's metabolism within a single cell. Such single-celled organisms are called unicellular. Other organisms are made up of many cells, with their cells specialized to perform distinct metabolic functions. One cell within an organism may be adapted for movement, while another cell carries out digestion. The individual cells no longer carry out all life functions, but rather depend on each other. Many-celled organisms are called multicellular. When a group of cells function together to perform an activity, they form a tissue. The cells of a human are organized into tissues such as muscle and nerve tissues. Plant tissues include those of the stem and root. Many cells in tissues are linked to each other at contact sites called cell junctions. Cell junctions help maintain differences in the internal environment between adjacent cells, help anchor cells together, and allow cells to communicate with one another by passing small molecules from one cell to another. Groups of two or more tissues that function together make up organs. An organ system is a group of organs that work together to carry out major life functions. Eukariotic Cell Structure: Boundaries and Control: Plasma Membrane - The plasma membrane is sometimes called the cell membrane, or the cellular membrane. It is the outermost part of the animal cell, and it's purpose is to enclose the cell, and change shape if needed. The cell membrane is capable of allowing materials to enter and exit the cell. Oxygen and nutrients enter, and waste products such as excess water leave. The plasma membrane helps maintain a chemical balance within the cell. Cell wall - The cell wall is an added boundary to the cell. It is relatively inflexible, and surrounds the plasma membrane. The cell wall is much thinker than the plasma membrane and is made of different substances in different organisms. The cells of plants, fungi, almost all bacteria, and some protists have cell walls. Animal cells have no cell walls. Plant cells contain cellulose molecules, which form fibers. This fibrous cellulose of plants provides the bulk of the fiber in our diets. Chitin, a nitr... ... pigments, molecules that give color. Structures for Support and Locomotion: The cytoskeleton is a network of thin, fibrous elements that act as a sort of scaffold to provide support for organelles. It also helps maintain cell shape in a manner similar to the way poles maintain the shape of a tent. The cytoskeleton is usually composed of microtubules and microfilaments. Microtubules are thin, hollow cylinders made of protein. Microfilaments are thin, solid protein fibers. Microtubules and microfilaments make up most of the sytoskeleton. Cilia - Cilia are only contained in some cells. They are short, numerous, hairlike projections out of the plasma membrane. Cilia tend to occur in large numbers on a cell's surface, and their beating activity is usually coordinated. Flagella - Flagella are longer projections that move with a whiplike motion. Cells that have flagella only have one or two per cell. In single-celled organisms, cilia and flagella are the major means of locomotion. Sperm cells of animals and some plants move by means of flagella. Organisms that contain many cells, including humans, have cilia that move fluids over a cell's surface, rather than moving the cell itself.