A+P O-Chem and Cell Review
Terms
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- microvilli
- minute extensions of the plasma membrane that increase surface area (usually for absorption)
- rough ER
- operates the cell's 'membrane factory'; creates integral proteins and phospholipids
- hydrostatic pressure
- movement of water and solutes through a semipermiable membrane from a region of higher hydrostatic pressure to lower hydrostatic pressure along a pressure gradient
- examples of membrane proteins' functions
- transport, enzymatic activity, receptors for signal transduction, intercellular joining, cell-cell recognition, attachment to cytoskeleton and ECM
- filtration
- the passive process that forces water and solutes through a membrane or capillary wall by fluid or hydrostatic pressure along a pressure (not concentration) gradient
- example of filtration
- movement of water, nutrients, and gases through a capillary wall; formation of kidney filtrate
- examples of gap junctions
- these junctions are often present in electrically excitable tissues, such as the heart and smooth muscle
- simple diffusion
- a passive process by which non-polar and lipid-soluble substances diffuse directly across the lipid bilayer.
- nucleus
- contains the 'genetic library'; dictates kinds and amounts of proteins to be synthesized
- tight junction
- a junction between plasma membranes of adjacent cells in which their integral protein molecules fuse together, forming an impermeable junction that encircles the cell
- examples of desmosomes
- for example, found in heart muscle and skin
- example of simple diffusion
- movement of fats, oxygen, carbon dioxide through the lipid portion of the bilayer
- ribosome
- site of protein synthesis in a cell; can be free-floating or membrane-bound on the Rough ER
- hypotonic
- eg, solutions that are more dilute (contain a lower concentration of non-penetrating solutes) than cells
- osmotic pressure
- a measure of the tendency of water to move into a concentrated solution
- desmosome
- "binding bodies" relying on intermediate filaments and cadherins that functionally "rivet" cells together in various locations across their membranes, and provide internal support within the cells
- example of osmosis
- movement of water into and out of cells directly through the lipid phase of the membrane via aquaporins
- cofactor
- the non-protein portion of a holoenzyme
- gap junction
- a communicating junction between adjacent cells, formed by hollow cyllinders composed of transmembrane proteins
- mitochondria
- the cell's 'power plant' provides most of the ATP supply
- cillia
- move substances in one direction across cell membrane
- apoenzyme
- the protein portion of a holoenzyme
- smooth ER
- performs lipid metabolism, synthesis of steroid-based hormones, detoxification (eg liver and kidneys)
- example of facilitated diffusion
- movement of glucose and some ions into cells
- lysosome
- the cell's 'demolition crew'; digests bacteria, viruses, toxins; degrades worn out organelles
- channels
- transmembrane proteins that serve to selectively transport specific substances, usually ions or water, through aqueous channels
- example of tight junctions
- junctions between epithelial cells lining the digestive tract, keeping digestive enzymes and microorganisms in the intestine from seeping into the bloodstream
- facilitated diffusion
- a passive process by which molecules such as glucose and other sugars, amino acids and ions are 'ferried' through the bilayer via through carrier proteins or through water-filled channel proteins
- aquaporin
- transmembrane protein that constitute a water-specific channel through which water can move freely and reversibly
- examples of microvilli
- often found in absorptive cells such as intestinal and kidney tubule cells
- osmolarity
- total concentration of all particles in a solution
- cytoskeleton
- machinery for locomotion/ motility
- holoenzyme
- an enzyme that consists of an apoenzyme and a cofactor