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165 Cards in this Set
- Front
- Back
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Light microscope
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Visible light passed through specimen and then focused; not able to resolve detail below 200 nm
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Organelles
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Subcellular structures; too small to be resolved by light microscopes
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Electron microscope
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Bombards specimens with electrons; able to resolve detail of 2 nm; cells are killed
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Cell ultrastructure
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Cell detail as resolved by electron microscopes
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Scanning electron microscope (SEM)
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Able to resolve 3D pictures of surfaces of cells; specimen coated with gold; agitated electrons picked up
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Transmission electron microscope (TEM)
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Beam fired through cross-section of cell; two-dimensional pictures
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Cell fractionation
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Separation of organelles via centrifuges
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Ultracentrifuge
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Most powerful centrifuges; 130,000 RPM max; 1 million g max force
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Cytosol
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Semifluid substance inside cells in which organelles are found
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Prokaryotic cell
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DNA is found in nucleoid; no membrane
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Nucleoid
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In a prokaryotic cell, where the nucleus is found
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Eukaryotic cell
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DNA is found in nucleus, enclosed by a membrane; larger than prokaryotic
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Cytoplasm
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Region between plasma membrane and nucleus of a cell
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Mycoplasmas
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Smallest bacteria cells; 0.1-1 micrometers
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Plasma membrane
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Selective barrier that allows passage of various things to cell; surface-area to volume ratio must be high
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Nucleus
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Contains DNA; most conspicuous organelle in most cells; contains chromatin, nucleolus; synthesizes mRNA
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Nuclear envelope
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Double-layered, pored membrane encasing nucleus
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Nuclear lamina
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Protein filaments that maintain nucleus's shape
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Nuclear matrix
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Network of fibers throughout nuclear interior
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Chromosomes
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Structures that carry genetic information; only recognizably shaped during cell division
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Chromatin
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Substance that makes up chromosomes; a mix of DNA and proteins; diffuse mass except during cell division
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Nucleolus
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Creates rRNA; assembles large and small ribosomal subunits; sometimes more than one
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Ribosomes
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Synthesize proteins from mRNA; made out of rRNA and proteins
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Free ribosomes
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Ribosomes that are suspended in the cytosol
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Bound ribosomes
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Ribosomes that are attached to ER; synthesize proteins for secretion, membranes or membrane-bound organelles (lysosomes)
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Endomembrane system
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System of membranes: synthesis of proteins; includes nuclear envelope, ER, Golgi apparatus, lysosomes, vacuoles, plasma membrane; related through vesicle use
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Vesicles
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Small sacs made of membrane segments; relates endomembrane system components
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Endoplasmic reticulum
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Network of membranous tubules and sacs (cisternae); ER membrane seperates ER lumen (inside cisternae) from cytosol
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Smooth ER
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ER without ribosomes; produces lipids; detoxifies toxins; stores calcium
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Rough ER
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Creates secretion proteins; creates membranes by expanding continually
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ER lumen
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Folds secretory proteins into their proper shapes; kept separate from cytosol
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Glycoproteins
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Proteins that have carbohydrates bonded to them
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Transport vesicles
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Formed from ER membrane; attaches to other membranes; contains proteins; synthesized from transitional ER
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Golgi apparatus
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Center of shipping, manufacturing, warehousing, sorting; made of cisternae; modifies proteins and lipids; modifies glycoprotein carbohydrates; transports to and from cisternae via vesicles; targets products for various areas of cell; dynamic structure
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Cis face / Trans face
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Cis face is receiving side of Golgi apparatus, located near ER; trans face is shipping side, located opposite cis face
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Lysosome
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Digestive membranous sac; contains enzymes, is acidic; formed by budding from Golgi apparatus trans face; digest food / cell products
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Phagocytosis
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Process of cells engulfing smaller organisms / macromolecules; forms food vacuole that connects with lysosome and digests engulfed substance; products are used as nutrients
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Macrophages
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White blood cell that used phagocytosis to destroy bacteria
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Autophagy
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Damaged organelle or cytosol is surrounded by membrane and taken to lysosome where it is digested
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Food vacuoles
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Formed by phagocytosis
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Contractile vacuole
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Water pump that expels excess water; in freshwater protists
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Central vacuole
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Develops from coalescence of smaller vacuoles; storage: stores proteins, ions, disposes of by-products, pigmentation, poison for predators, growth as vacuoles enlarge with water; occupies a lot of space
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Tonoplast
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Membrane enclosing central vacuole
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Mitochondria
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Engages in cellular respiration; double-membraned; outer membrane is smooth, inner is folded; different proteins embedded in each; reproduce on their own and contain their own DNA; not part of endomembrane system
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Cristae
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Folds in inner mitochondrial membrane; increases surface area and allows presence of more proteins
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Mitochondrial matrix
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Inner compartment of mitochondria; contains enzymes for ATP production; contains free ribosomes for mitochondrial synthesis; contains mitochondrial DNA
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Chloroplasts
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Member of plastids group; contain green pigment chlorophyll; engages in photosynthesis; reproduce themselves, contain DNA; separated from cytosol by at least 2 membranes
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Plastids
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Amyloplasts: store starches, colorless; chromoplasts: contain pigments that give yellow and orange hues; chloroplasts: see above
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Thykaloids
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Poker chip-like shapes inside chloroplasts
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Granum
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A stack of thykaloids
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Stroma
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Fluid outside thykaloids inside chloroplasts
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Peroxisomes
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Metabolic compartment bounded by single membrane; transfers hydrogen from a substance to oxygen, produces hydrogen peroxide; breaks fatty acids down for use in mitochondria; detoxifies compounds like alcohol and hydrogen peroxide; do not bud from endomembrane system; reproduce by splitting
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Glyoxysomes
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Enzymes that initiate conversion of fatty acids to sugar in fat-storing tissues to kickstart growth of seedlings
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Cytoskeleton
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Network of structural fibers extending throughout cell's cytoplasm
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Motor proteins
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Participate in cell motility; attach to cytoskeleton and motor protein receptor
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Cell motility
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Encompasses both cellular motion as a whole and intracellular motion; often pattern of movement is provided by cytoskeleton (vesicles travel along monorails; manipulates plasma membrane during phagocytosis)
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Microtubules
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Thickest type of fiber in cytoskeleton; shape and structure support; tracks along which organelles can move (secretory vesicles); resist compression
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Centrosome
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A region that is a "microtubule-organizing center"; origin of microtubules; compression resistance
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Centriole
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Only in animal cells; rings of triplets of microtubules; purpose unknown, centrioles replicate before cell division; within centrosome
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Flagella
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Beating structures extending from cell; provides force in same direction of cell movement; typically small in number
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Cilia
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Beating structures extending from cell; provides force 90 degrees from direction of cell movement; typically large in number; used when cells are held in place to move substances along tissue surface
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Flagella / cilia ultrastructure
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Core of microtubules sheathed in plasma membrane; 9 doublets of microtubules in a ring connected by cross-linking proteins to 2 central microtubules
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Basal body
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Centriole-like structure anchoring cilia / flagella in place
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Dynein
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Motor proteins connecting outer doublets of cilia / flagella; their movement causes cilia / flagella to bend
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Microfilaments
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Filaments of cytoskeleton that bear tension; gives outer cytoplasmic layer gel consistency; make up microvilli; causes cell contraction / expansion (muscle cells); cell motility of amoeba
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Actin
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Protein that makes up microfilaments
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Myosin
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Filaments made of this are connected with microfilaments and they walk along each other to cause cell contraction / expansion
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Pseudopodia
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Cellular extensions involved in amoeba movement
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Cytoplasmic streaming
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Circular motion of cytoplasm that distributes materials throughout a cell; results from actin-myosin interactions; in large plant cells
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Intermediate filaments
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Bears tension; diverse; upholds cell structure almost entirely; nuclear lamina
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Cell wall
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Extracellular plant cell structure that retains plant cell shape and prevents excessive uptake of water; cellulose is embedded in a matrix of other polysaccharides and proteins
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Primary cell wall
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Outer cell wall; thin and flexible
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Middle lamella
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Between primary cell walls of adjacent cells; sticky substance that glues cells together; made of pectins
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Secondary cell wall
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Located between plama membrane and primary cell wall; deposited in layers; strong and durable
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Extracellular matrix
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Consists of glycoproteins; links different cells; affects cell behavior and migration
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Collagen
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In ECM, forms strong fibers between cells; embedded in proteoglycan network
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Proteoglycans
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Weaves network that collagens are part of; 95% carbohydrates
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Fibronectin
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Connects cells to extracelular matrix by bonding to integrins
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Integrins
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Bonds to fibronectin to connect cells to ECM
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Plasmodesmata
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Channels in cell walls of plant cells that connect adjacent cells' cytosol
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Tight junctions
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Membranes of neighboring cells are pressed against one another and bound by proteins; does not allow fluid to pass through
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Desmosomes
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Like rivets that fasten cells together; extend into the cell
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Gap junctions
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Connects small pores in plasma membrane that allows molecules to pass from one cell to another; allows communication
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Selective permeability
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When a membrane allows some substances to pass through it more easily than others
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Amphipathic molecule
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A molecule with both a hydrophilic and hydrophobic portion; phospholipids are amphipathic
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Fluid mosaic model
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The model of a cell membrane as a fluid structure with embedded proteins
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Davson and Danielli
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They proposed an incorrect model with a phospholipid bilayer coated with proteins; differences in membranes, and the fact that proteins' hydrophobic portions would be immersed in water disproved it
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Cholesterol
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Restrains movement of phospholipids in the cell membrane and stabilizes membrane
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Integral proteins
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Proteins that go through the hydrophobic core of the membrane
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Transmembrane proteins
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Proteins that go entirely through the membrane
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Peripheral proteins
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Proteins that are not lodged in the bilayer but are loosely bonded to the outside; often attached to integral proteins
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Glycolipids
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Lipids with carbohydrates bonded to them; arrangement of carbohydrates has a part in cell-cell recognition
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Glycoproteins
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Like glycolipids but with proteins instead
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Transport proteins
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Proteins that selectively allow certain substances to pass through a membrane
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Channel proteins
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Proteins with a hydrophilic channel that allows certain materials to pass through the protein
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Aquaporins
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Channel proteins that allow water to cross the cell membrane
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Carrier proteins
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Proteins that change shape and selectively bond to specific molecules to shuttle them through to the cell
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Diffusion
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The tendency of a substance to spread out until the concentration of the substance is even throughout a solution
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Concentration gradient
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The direction a substance will diffuse without any work being done
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Passive transport
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Transport of substances due to diffusion across a biological membrane; no work must be done in order to make passive transport occur
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Osmosis
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The diffusion of water across a selectively permeable membrane
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Tonicity
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The ability of a substance to cause cells to gain or lose water
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Isotonic solution
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If a solution is isotonic to a cell, the net movement of water across the cell's membrane will be zero
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Hypertonic solution
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If a solution is hypertonic to a cell, the net movement of water across the cell's membrane will be out of the cell (the cell will lose water)
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Hypotonic solution
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If a solution is hypotonic to a cell, the net movement of water across the cell's membrane will be into the cell (the cell will gain water)
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Cytolysis / lysis
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The rupturing of a cell due to immersion in a hypotonic solution
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Osmoregulation
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The regulation of water balance in or out of the cell (may involve contractile vacuoles, etc.)
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Turgid
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The firmness of a plant cell due to immersion in a hypotonic solution
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Flaccid
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The limpness of a plant cell due to immersion in an isotonic solution
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Plasmolysis
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The process of a cell's membrane drawing back from its cell wall due to immersion in a hypertonic solution
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Facilitated diffusion
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Passive diffusion with the help of transport proteins; they allow substances to cross the membrane more quickly
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Gated channels / ion channels
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Channels that open or close in response to a stimulus
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Active transport
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Transport through proteins that expends energy to move solutions across their concentration gradients; energy supplied by ATP
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Sodium-potassium pump
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ATP changes configuration of protein; allows sodium to pass in one direction and potassium to pass in the other
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Membrane potential
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Charge difference between solution on one side of a membrane and solution on the other
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Electrochemical gradient
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A combination of electrical and chemical forces (concentration gradient) and electrical forces on an ion that affect diffusion
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Electrogenic pump
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Transports ions across a cell membrane against their electrochemical gradients, increasing membrane potential
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Proton pump
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An electrogenic pump for H+ ions (protons); this is the major electrogenic pump in non-animal eukaryotic cells; for animal cells it's the sodium-potassium pump
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Cotransport
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When proteins couple the diffusion of a particle down its concentration gradient with the active transport of another particle against its concentration gradient
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Exocytosis
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The transport of particles out of a cell; vesicles connect with the cell membrane and empty their contents out of the cell
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Endocytosis
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The transport of molecules into a cell by forming new vesicles / vacuoles
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Phagocytosis
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The transport of large molecules or organisms into cells by the extension of pseudopodia; it forms a vacuole rather than a vesicle
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Pinocytosis
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The transport of small extracellular particles into the cell via the formation of pockets in the cell membrane; the pockets later pinch off into the cell to form vesicles full of various small particles
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Receptor-mediated endocytosis
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When ligands that are not in high extracellular concentration bind to receptor proteins on a cell and are then taken into the cell in coated vesicles (coated with a fuzzy layer of coat proteins)
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Ligands
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Substances that bind to the receptor proteins in receptor-mediated endocytosis
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Metabolism
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The sum total of chemical reactions in an organism
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Metabolic pathway
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Where one molecule is altered into another or a group of other molecules, and the steps in between; each step is catalyzed by a certain enzyme
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Catabolic pathway
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Where a large molecule is broken down into smaller ones and energy is released
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Anabolic pathway
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Where energy is taken and smaller molecules are used to synthesize larger ones
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Bioenergetics
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The study of how organisms manage their energy resources
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Kinetic energy
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The energy associated with the motion of objects
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Thermal energy
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Energy associated with the motion of molecules
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Potential energy
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Energy that is not currently being used by a system
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Chemical energy
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Energy stored in chemical bonds; energy available for release when a chemical reaction takes place
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Thermodynamics
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The study of energy transformations in matter
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First law of thermodynamics
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The energy of the universe is constant; it cannot be created or destroyed
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Entropy
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A quantitative measurement of randomness
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Second law of thermodynamics
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Every energy transformation will increase the entropy of the universe as a whole
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Spontaneous
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Used to describe processes that can occur without an input of energy; spontaneous processes must increase the entropy of the universe
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Free energy
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The amount of energy in a system that is available to perform work when pressure and temperature are uniform; ∆G =∆H- T∆S
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Equilibrium
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When the backwards and forwards reactions occur at the same rate; also, when G (the amount of free energy) is at its lowest point
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Exergonic reaction
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A spontaneous reaction; it releases free energy and ∆G is negative; decreases the overall G of a system
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Endergonic reaction
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A non-spontaneous reaction, where work has to be done; it consumes free energy and ∆G is positive
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Energy coupling
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When the free energy released by an exergonic reaction is used to drive an endergonic reaction
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ATP (adenosine triphosphate)
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Phosphate groups are broken off to release free energy; coupled in a lot of reactions; instable due to crowded phosphate groups (negative charges)
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Phosphorylated
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When a molecule becomes phosphorylated, a negatively-charged phosphate group is added to it, making it less stable and increasing its reactivity; can change shapes of proteins to due mechanical and transport work
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Catalyst
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A chemical agent that speeds up a chemical reaction
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Enzyme
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A type of protein catalyst; molecules fit into active sites on the protein and reactions between them are sped up in various ways; always catalyzes in the direction of equilibrium
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Activation energy
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The initial energy required to start a reaction (energy needed to destabilize bonds between atoms)
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Substrates
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Reactants that an enzyme acts upon
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Enzyme-substrate complex
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When a substrate bonds to an enzyme it forms an enzyme-substrate complex for the duration of the chemical reaction
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Active site
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The area a substrate bonds to on an enzyme; usually a pocket or groove of some sort
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Induced fit
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The shape that an enzyme's active site changes into to snugly fit around the substrate after being loose before
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Methods of catalysis in enzymes
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Provides a template for reactants; stretches substrates toward transition state; microenvironment more conducive to reactions; direct participation
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Enzyme saturation
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When substrates leave enzymes at the same time as they enter
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Optimal conditions
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Most enzymes have optimal temperatures and pHs that they work under; if they go too far outside of their optimal range their rate might slow to a crawl or they might denature
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Cofactors
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A nonprotein helper required for an enzyme to function properly; they may be inorganic molecules
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Coenzymes
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Any organic cofactor
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Competitive inhibitors
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Chemicals that bind to an active site of an enzyme to prevent proper substrates from entering
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Noncompetitive inhibitors
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Chemicals that bind to a separate location on the enzyme from the active site, causing the shape of the active site to change so that the proper substrate no longer fits
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Allosteric regulation
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Regulation of an enzyme's operation by inhibiting / activating the enzyme purposefully
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Activator
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A molecule that, in allosteric regulation, stabilizes the active (fuctional) form of an enzyme
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Inhibitor
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A molecule that, in allosteric regulation, stabilizes the inactive (nonfunctional) form of an enzyme
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Cooperativity
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When the binding of a substrate to one enzyme in a group causes all of the other enzymes in the group to become active
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Feedback inhibition
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When a metabolic pathway is inhibited by its own end product; it regulates the amount of product that can be produced; sometimes the original reactant can also be used as an activator
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