The cytoplasm is composed of the cytosol the

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14. THE CYTOPLASM is composed of the cytosol, the cytoplasmic organlles, and inclusions. The cytoplasmic organelles include:a.i.The mitochondria is “the powerhouse” of the cell and it is the home of aerobic respiration to release energy, it has resident enzymes of the cristae (inner membrane foldings) and the matrix breakdown food in the presence of oxygen; it also contains its own DNA and is changing its shape constantly.a.ii.Ribosomes consist of 2 globular subunits, small and large ribosomal units and each ribosomal subunit consists of protein and rRNA. The free ribosomes float in the cytosol and synthesize proteins that stay in the cell. The bound ribosomes are bound to the rough ER and synthesize proteins
that are transported to the plasma membrane or for export out of the cell (secreted).a.iii.The rough ER is an external surface that is studded with ribosomes and the rough ER is abundant in secretory cells such as liver cells. The rough ER is known as the “Membane Factory” because the synthesis of integral proteins and phospholipids in plasma membranes is associated with the rough ER. a.iv.The smooth ER has no ribosomes. The smooth ER has special smooth muscle cells that are called Sarcoplasmic Reticulum which stores and releases calcium. The smooth ER’s membrane-bound enzymes catalyze-a.iv.1.Synthesis of fats, cholesterol, and steroid hormonesa.iv.2.Fat absorption, transport and metabolisma.iv.3.Glycogenolysis which results in energy productiona.iv.4.Detoxification of drugs and carcinogens in liver and kidney cells.a.v.Lysosomes are spherical membranous organelles and they contain powerful digestive enzymes that digest vesicles and biological molecules. They digest phagosomes, which means they are abundant in phagocytes. They digest worn- out oganelles, they stimulate glycogenolysis, and are involved in resorption to release calcium. They are known as the “demolition crew” because they also digest non useful tissues.a.vi.Peroxisomes are membranous sacs that contain powerful enzymes that neutralize harmful free radicals. There are two kinds of enzymes in peroxisomes: oxisases and Catalases. Free radicals (harmful) +oxidases = hydrogen peroxide (harmful). Hydrogen peroxide + catalases = water.a.vii.The Golgi Apparatus is “the traffic director” which is composed of stacked and flattened membranous sacs and receives proteins and lipids from the rough ER. The golgi modifies, packages, and tags proteins and lipids to their specific destinations. There are three types of vesicles that are produced by the golgi:
a.vii.1.Secretory vesicles which contain proteins released via exocytosis.a.vii.2.Vesicles that contain integral proteins and lipids destined for the plasma membrane to incorportated into the plasma membrane.a.vii.3.Vesicles containing powerful digestive enzymes that will remain in the cell and they are lysosomes.b.THE CYTOSKELETON consists of non membranous rod- like structures that support other cytoplasmic organelles and allow for movements:b.i.

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