Different Types of Cells

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Different types of cells and their ultra structure
The cell is the basic unit of life. Each cell can be regarded as a metabolic compartment, a separate place where the chemical processes of that cell occur. Cells are often designed to perform a particular function. Depending on that function, each cell type has an internal structure that suits it for its job. This is known as the ultrastructure of the cell. There are different types of cells inside the human body. They are the epithelial cells, muscle cells, nerve cells, bone cells and muscle cells. Epithelial cells are eukaryotic cells. Eukaryotic cells have a distinct nucleus and possess membrane-bounded organelles. They differ from prokaryotic cells, such as bacteria. The function of epithelial cells is to absorb and secrete. Epithelial cells have a nucleus which acts as the control centre of the cell through the production of mRNA and hence protein synthesis. They also have mitochondria which are the sites of aerobic respiration. They are therefore responsible for the production of the energy carrying molecule, ATP, from carbohydrates. Epithelial cells use a lot of energy in the process of absorbing substances from the intestines by active transport therefore they have many mitochondria for plentiful supply of ATP. They are also found extensively in muscle cells as muscles need continuous supply of ATP during rapid movement such as exercising. Epithelial cells also contain Endoplasmic Reticulum which are divided into two types; the rough ER, which has ribosomes present on the outer surfaces of the membranes. Its functions are to: provide a large surface area for the synthesis of proteins and glycoproteins and to provide a pathway for the transport of materials, especially proteins, throughout the cell. The smooth ER lacks ribosomes on its surface and is often more tubular in appearance. Its functions are to: synthesise, store and transport lipids and to synthesise store and transport carbohydrates....
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