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Cells
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Structural and functional units of the human body
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Describe how every individual begins life.
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Every individual begins life as a single cell, a fertilized egg. Then, divides into 2 cells, then 4, 8, 16 and so on.
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Differentiation
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-during development cells become specialized in size, shape, characteristics, and function
-variety of cells |
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Plasma (cell) membrane
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-separates the material outside the cell (extracellular) from the material inside the cell (intracellular)
-maintains the integrity of the cell -if broken or ruptures, the cell dies |
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Selectively permeable
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-determines what can go into or out of the cell
-some substances can pass through the membrane but other cannot |
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What are the main structural components of the plasma membrane?
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1. phospholipids
2. proteins |
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Phospholipids
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-arranged in a double layer (bilayer)
-cheese sandwich |
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Hydrophilic
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Attract water and other polar molecules
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Hydrophobic
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Water will not mix with it
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"fingerprints"
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-proteins on the surface of the cell that act as markers for identification
-enable the body to recognize and accept its own cells but reject those that are foreign |
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Cytoplasm
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-the gel-like fluid inside the cell
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Organelles
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-"little organs"
-functional machinery of the cell -each type has a specific role in the metabolic reactions that take place in the cytoplasm |
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Intracellular fluid
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-primarily water
-contains dissolved electrolytes, metabolic waste products and nutrients (amino acids and simple sugars) |
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Inclusions
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Bodies that are temporarily in the cell but that are not a part of the permanent metabolic machinery of the cell
ex. secretory products, glycogen granules, pigment granules and lipid droplets |
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Nucleus
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-the control center that directs the metabolic activities of the cell
-all cells have at least 1 at some time -relatively large, spherical body -usually in the center of the cell |
