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ch3notes - Types of tonicity Tonicity describes the...

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Types of tonicity: Tonicity: describes the behavior of cells in a fluid environment. Hypertonic:(hyper-osmotic): soultion has higher concentration of solute on the outside. This results in a net movement of water out of the cell. (EX- food preservation) hypotonic(hypo-osmotic): solution has a lower concentration on the outside. This results in water moving into the cell. Isotonic: an extracellular solution that has the same concentration of soulute as what is in the cell. There is no net movement of water in or out of cells. Hydro-static pressure: ( fluid mechanics ) The pressure at a point in a fluid at rest due to the weight of the fluid above it. Also known as gravitational pressure. The negative of the stress normal to a surface in a fluid. *The pressure exerted or transmitted by the fluid (e.g. water ) at rest. Osmotic pressure: the more solute particles present, the higher the osmotic pressure, (Osmotic pressure depends only on the number of solute particles present in a solution , not the kinds of solute particles.) cell differentiation: The process whereby relatively unspecialized cells, e.g. embryonic or regenerative cells, acquire specialized structural and/or functional features that characterize the cells, tissues, or organs of the mature organism or some other relatively stable phase of the organism's life history. Differentiation includes the processes involved in commitment of a cell to a specific fate. *governed by genes. Your body "tunes" the genes of each cell type differently. Depending on where in the body it is located, a given gene can be turned off, weakly on, or strongly on. For example, the gene for globin, which composes hemoglobin, is strongly on in cells that will mature into red blood cells and off in every other cell type. Cells control the tuning, or expression, of genes by keeping a tight rein on RNA polymerase. For genes that are strongly on, cells use special molecular tags to lure in RNA polymerase and to ensure that the machine works overtime transcribing those genes. For genes that are off, cells use different tags to repel RNA polymerase. Receptor mediated endocytosis: is a process by which cells internalize molecules or viruses. As its name implies, it depends on the interaction of that molecule with a specific binding protein in the cell membrane called a receptor. Pinocytosis: ("cell-drinking", "bulk-phase pinocytosis", "non-specific, non-adsorptive pinocytosis", "fluid endocytosis") is a form of endocytosis in which small particles are brought into the cell suspended within small vesicles which subsequently fuse with lysosomes to hydrolyze, or to break
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down, the particles. This process requires energy in the form of adenosine triphosphate (ATP), the chemical compound used as energy in a majority of cells. Pinocytosis is primarily used for the absorption of extracellular fluids (ECF), Membrane receptors Cell-cell communication is by chemical messenger.
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