The human cell Term Paper Example | Topics and Well Written Essays - 4500 words

The human cell - Term Paper Example It has organelles for various functions. The chemical processes and complex interactions that occur inside the cell form the bridge between the nonliving and the living (Sherwood 2010). Inside the human body, various processes that go on synchronized to provide an efficient healthy functioning are interrelated and coupled for optimum functional output. This requires organization at various levels. In complex living beings like humans, there are many levels of organization, as opposed to single cellular organisms like bacteria. The study about the cell and its structure was revolutionized with the invention of microscope. The discovery of microscope in 16th century encouraged scientists to study these basic building blocks. It was Robert Hooke who discovered the cell in 1965 and named it Cellulae (Latin: tiny rooms) as he observed box like structures in a thin slice of cork under his microscope (Lee et al 2009). He was the first one to describe the fungus Mucor. Later Antony Van Leeuw enhoek improved the microscope and documented some initial findings about protozoa and bacteria (Gest 2004). The contributions of Matthias Schleiden, Theodor Schwann and Rudolf Virchow lead to the development of ‘The Cell Theory’ in 1839. According to the cell theory: 1. All living things are made from one or more cells. 2. The cell is the basic unit of life. 3. All cells come from preexisting cells. Thus the cell is an essential component of the human body and this paper will explore the organization and cellular membrane of  the cell. It will also analyze the energy processes of the cells accompanied with the enzymes and the metabolic activities of the cells. ORGANIZATION OF CELLS Advances in microscopy and imaging led to further research into the cell structure. It is now established fact that cells are composed of various organelles and there are complex signaling pathways that control the expression of various molecules. The structure and composition of different cell types vary, but certain characteristics are common to all cells. Cells of similar kind together form the tissues (Marieb 2006). There are four basic types of tissues that form the entire organism, epithelium, supporting or connective tissue, muscle and nerve tissue. Organs are formed by two or more tissue types combined together for a specific function. One tissue type forms the parenchyma, the functioning part of the organ, while other tissues provide the supporting frame work, i.e. the stroma (Crowley 2007). The organization of different organs working together to perform a particular function forms the organ system, like nervous system, digestive system, musculoskeletal system and others. Finally, the different organ systems work together in an individual to maintain a state of homeostasis and optimum health functions (Ganong 2005; Guyton et al 2007). Protoplasm and Cell Membrane: The basic cellular structural components are similar in all cell types. Cells are bounded by a plasma membrane (cell membrane) and contain the fluid called protoplasm. The protoplasm is divided in clear cytoplasm and the central nucleus. The protoplasm is made up of five basic substances, water, carbohydrates, proteins, lipids and electrolytes. Water is the basic fluid medium of cell and forms up to 75- 80% of its concentration. It provides a medium for the suspension of particulate matter and in which chemical reactions can take place. Proteins are the building blocks of cells and form up to 10- 20 % of cell mass. They are of two types, functional and structural. Functional proteins are the enzymes that catalyze the cell reactions. They can be present as part of the membranes or can be mobile and catalyze the reactions as