Cells160-page14 - • Some protists such as Amoeba feed by...

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Cell - 14 Vesicles: Lysosomes and other "—somes" Golgi Vesicles Most Golgi vesicles are temporary structures, formed to transport manufactured molecules for export from the cell. Vesicles may also be formed at the plasma membrane for import of substances into the cell, a process called pinocytosis, which we will discuss later. Other vesicles form organelles, each containing enzymes needed for specialized functions within the cell. Lysosomes contain hydrolytic enzymes, which can breakdown carbohydrates, proteins, nucleic acids, and many lipids. Lysosomes are manufactured from enzymes and membranes of the rough ER and packaged in the Golgi complex. The Lysosome is responsible for disassembly or breakdown of cell components when no longer needed or when damaged or in need of recycling. It is a normal part of cell maintenance and renewal. Lysosomes can also destroy or degrade bacteria and foreign substances. Macrophages for example, contain large numbers of lysosomes.
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Unformatted text preview: • Some protists, such as Amoeba feed by a process of phagocytosis. The food vacuole formed merges with lysosomes for digestion. • Plant cells do not need lysosomes; breakdown products of plants are stored in their central plant vacuoles (see later) Lysosome Phagocytosis and Food Vacuole formation Peroxisomes Peroxisomes contain enzymes that transfer hydrogen in biochemical reactions to oxygen, forming hydrogen peroxide as a by-product. Since H 2 O 2 is toxic, peroxisomes also contain an enzyme, catalase, which breaks down the H 2 O 2 . Glyoxysomes Plant cells, especially in seeds, contain glyoxysomes. These cells store oils so that the germinating seed has a fuel supply. During germination, the fatty acids are converted to sugar molecules for the rapid cell respiration needed for successful germination and seedling establishment....
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