Chapter 4 - Chapter Outline - Organization of the Cell

Chapter 4 - Chapter Outline - Organization of the Cell -...

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Purav Patel Chapter 4 AP Biology Organization of the Cell Introduction German scientists Schleiden and Schwann used inductive reasoning to conclude that all plants and animals consist of cells. Later, the German Virchow saw new cells form through the division of previous cells. Cell Theory - the unifying concept that (1) cells are the basic units of organization and (2) cells come from other cells. The German biologist Weismann saw that cells share structural similarities and concluded that the existence of all the cells alive today derived from a single cell. Cells rarely obtain energy from one form to another, and that energy is used to carry out mechanical activities and chemical synthesis. Cells convert energy to a convenient form like ATP. The chemical reactions that convert energy from one form to another are essentially the same in all cells. Technology benefits the study of cells. By advances in microscopy, the cytoskeleton was studied in greater detail. The microtubules of cells are clearly visible in photographs aided by advanced microscopes. Cell Organization and Size Homeostasis - the internal maintenance of a stable environment in a cell To enable the functioning of cellular biochemical functions, cells maintain homeostasis in response to changes in salt concentration, pH changes, and temperature. The Organization of All Cells is basically similar Plasma Membrane - structurally distinctive surface membrane that surrounds all cells The plasma membrane allows the chemical composition of the inside of the cell to be maintained differently from the chemical composition of the outside of the cell. Cells exchange materials with the environment to accumulate needed substances and energy stores. Organelles - internal structures in cells specializing in metabolic activities such as energy conversion, compound synthesis, and manufacturing structures for functioning and reproduction Cell Size is Limited The micrometer (one millionth of a meter) is used to measure cells. The nanometer (one billionth of a meter) is used to measure cellular components. 1
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Purav Patel Chapter 4 AP Biology Human egg cells, some algae, and a few kinds of animal cells are visible to the naked eye. The cells of birds’ eggs are visible to the naked eye, though they are atypical cells. The plasma membrane contains specialized pumps and channels with gates that are selectively permeable , or regulating what comes in and out of the cell. The plasma membrane must be large enough relative to the cell volume to keep up with the demands of regulating the passage of materials. Thus, a cell’s surface area to volume ration is a critical factor in determining cell size. As a cell becomes larger, its volume increases at a greater rate than its surface area, limiting cell size. Above some critical size, the entrance and exit of nutrients, wastes, and ions fails to enter and
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Chapter 4 - Chapter Outline - Organization of the Cell -...

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