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79 Cards in this Set
- Front
- Back
cells
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structure units of living things,
smallest living unit, composed of C,H,O,N |
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cell theory
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1)cell-basic structural/functional unit
2)organism activity-depends on cell activities 3)principle of complementarity- cell activity dictated by structures 4)continuity of life-has cellular basis |
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generalized cell
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parts: 1)plasma membrane
2)cytoplasm 3)nucleus |
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Fluid mosaic model
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depicts plasma membrane as thin structure of bilayer of lipid molec w/ protein molec
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lipid bilayer
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consists of phospholipids w/ cholest & glycolipids
-phospholipids: unsaturated- kinks tail increase space |
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glycolipids
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-phospholipids w/ attached sugar groups
-found on outer plasma membrane surface |
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lipid rafts
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-20% of outer membrane surface
-assemblies of saturated phospholipids w/ unique lipids: sphingolipids & cholest -platforms for signaling |
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integral proteins
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-inserted into lipid bilayer
-have hydrophilic/hydrophobic regions -transmembrane proteins:span membrane & protrude both sides |
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transmembrane proteins
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-involved in transport
-cluster to form channels (pores) -act as carriers-bind to substances -receptors & relay messages to cell interior (signal transduction) |
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peripheral proteins
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-not embedded in lipid
-attach loosely to integral proteins or membrane lipids -include network of filaments that help support membrane |
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glycocalyx
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fuzzy, sticky carb. rich area
"sugar-coated" enriched by glycolipids & glycoproteins provides specific biological markers |
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microvilli
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-fingerlike extensions of membrane that project from free/exposed cell surface
-increase plasma membrane surface area -have actin:contractile filaments -acts as mechanical stiffener |
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3 factors of membrane junctions
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1) glycoproteins in glycocalyx act as adhesive
2) wavy contours- fit in tongue & groove fashion 3) special junctions formed: tight junctions, desmosomes, gap junctions |
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tight junctions
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adjacent cells fuse together to form impermeable junction
expl: digestive tract |
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desmosomes
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-anchoring junctions
-mechanical coupling scattered (rivets) -plaque: buttonlike thickening -adjacent cells held together by linker protein filaments -abundant in tissues of mechanical stress -expl: skin, heart muscle |
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gap junctions
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-cells connected by hollow cylinders-connexons
present in excitable tissues-heart/smooth muscle |
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interstitial fluid
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-extracell. fluid
-derived from blood -contains amino acids, sugars, fatty acids |
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plasma membrane
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-selectively permeable barrier
allows subs. to pass while excluding others |
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processes
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passive- cross membrane w/o energy
active- needs ATP to move |
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passive processes
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2 types: diffusion & filtration
diffusion- occurs in every cell filtration-occurs across capillary walls |
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diffusion
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-tendency of molec. to scatter evenly
-move from high to low concentration and diffuses along concentration gradient -driving force: kinetic energy |
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simple diffusion
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-unassisted diffusion of lipid-soluble or small particles
-rate not controllable |
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osmosis
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unassisted diffusion of solvent (water)
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facilitated diffusion
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-assisted diffusion & highly selective
-rate controllable by regulating carriers -binds to protein carriers in membrane |
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carrier
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-transmembrane integral protein that shows specificity for molec of large polar subs.
1) envelop then release transported subs. 2) binding site: moved from one membrane to other |
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channels
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-transmembrane proteins that serve to transport subs. through aqueous channels
-selective b/c of pore size & charges of amino acids |
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types of diffusion
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1) simple diffusion
2) facilitated diffusion 3) osmosis |
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osmosis
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-diffusion of solvent (water), selectively permeable
-occurs when water concent. differs |
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aquaporins
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water specific channels constructed by transmembrane proteins
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osmolarity
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total concentration of solute particles in solution
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hydrostatic pressure
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back pressure exerted by water against membrane which equals osmotic pressure-cell's tendency to resist water entry
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tonicity
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ability of solution to change shape by altering internal water volume
-depends on 1) solute concent. 2) solute permeability |
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isotonic
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-"same tonicity"
-same concentration of nonpenetrating solutes -retain normal shape & no change in water |
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hypertonic
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-solution w/ higher concentration than in cell
-cell lose water & crenate (shrink) |
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hypotonic
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-solutions contain lower concent. than cells
-cells plump & water rushes into them then bursts and lyse |
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selectivity
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simple diffusion & osmosis are not selective
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filtration
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process that forces water/solutes through membrane
gradient: pressure-pushes solute-containing fluid (filtrate) from low to high |
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active processes
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uses ATP
types: 1)primary active transport 2)secondary active transport |
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active transport
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requires carrier proteins that combine specifically & reversibly w/ subs.
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primary active transport
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-hydrolysis of ATP
-active transporters/solute pumps move solutes against concent. gradient -expl: sodium potassium pump |
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active transport: Na+-K+ pump
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carrier: enzyme Na+-K+
-ionic concent. differences essential to maintain fuction -Na+-K+ leak slowly but continuously along concent. ground -Na+-K+ pump ejects 3 Na+ out of cell, 2 K+ back in cell -maintains membrane potential & osmotic balance |
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secondary active transport
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Na+-K+ pump indirectly drives secondary active transport
-moves Na+ membrane against concent. gradient |
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vesicular transport
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-energized by ATP
-transport large particles, macromolecules, & fluids -used for exocytosis & endocytosis |
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transcytosis
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moves substances into, across, out of cell
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vesicular trafficking
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move subs. from one area to another
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phagocytosis
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cytoplasmic extensions (pseudopods) form & engulf particle
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membrane potential
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voltage across membrane
voltage- electrical potential energy |
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resting membrane potential
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-50 to -100 mV
all cells polarized |
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cell adhesion molecules (CAMs)
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anchor cells to extracellular matrix
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membrane receptors
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contact signaling- important in normal development & immunity
electrical signaling- enrve impulse chemical signal- neurotransmitters signal nerve impulse -lygand (G-protein): 1st messenger |
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cytoplasm
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material between plasma membrane & nucleus
cytosol- water w/ dissolved protein, salts, sugars |
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mitochondria
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-double membrane structure
-produce ATP: need glucose & Oxygen -responds to needs of ATP |
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ribosomes
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responsible for synthesizing protein
found in ER & cytosol |
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endoplasmic reticulum
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-rough ER contains ribosomes
-smooth ER is not studded w/ ribosomes |
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smooth ER
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-tubules arranged in looping network
-catalyzes reaction in liver -breaks down alcohol/drugs |
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golgi apparatus
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"fedex"
stacked & flattened membranous sacs function: modification, concent. & packaging of proteins |
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lysosomes
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-spherical membranous bags containing digestive enzymes
-breakdown nonuseful tissue -breakdown bone to release calcium |
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endomembrane system
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system of organelles:
produce, store, export biological molecules |
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peroxisomes
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-contain peroxidase- help form water molec.
-membranous sacs contain oxidases/catalases -detoxify harmful or toxic subs. -neutralize dangerous free radicals |
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free radicals
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highly reactive chemicals w/ unpaired electrons
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cytoskeleton
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skeleton of cell (framework)
dynamic, elaborate series of rods |
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3 types of rods in cytoskeleton
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1) microtubules
2) microfilaments 3) intermediate filaments |
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microtubules
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-elements w/ largest diameter, hollow tubes made of spherical protein
-determine cell shape & distribution of cellular organelles |
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motor proteins
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tiny protein machines and pulled along microtubules
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microfilaments
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thinnest elements of cytoskeleton
strands of actin |
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intermediate filaments
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-tough, insoluble protein fibers that have diameter between microfilaments & microtubules
-most stable & permanent -have high tensile strength |
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cilia
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whiplike, motile cellular extensions on exposed surfaces
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nucleus
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-contains nuclear envelope, nucleoli, chromatin
gen-containing control center of cell |
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nuclear membrane
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-selectively permeable double membrane
-supported by lamina propia & ER |
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nucleoli
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ribosomal protein
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chromatin
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-threadlike strands of DNA & histones
-DNA wrapped around proteins |
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network of protein tubules that support & maintain shape of cell
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microtubules
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these proteins span the plasma membrane and are often channel proteins or carrier proteins
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integral proteins
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specialized, finger like projections of the plasma membrane that increase the cell surface are
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microvilli
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this membrane junction uses protein plaques with the linking proteins between them to join adjacent cell membranes; found in the skin
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desmosomes
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this transport process uses a carrier protein but no ATP to move molecules down its concentration gradient
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facilitated diffusion
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this organelle is primarily responsible for lipid metabolism and detoxification of drugs
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peroxosomes
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this nuclear region synthesizes ribosomal subunits
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nucleus
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this spherical organelle contains digestive enzymes that break down waste or glycogen
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lysosomes
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