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Bio Chapters 4-5,9
| Term | Definition |
|---|---|
| light microscope | when visible light is passed through the specimen and then through glass lenses; lenses bend light to magnify the image when it hits the eye or camera |
| magnification | ratio of an object's image size to its real size |
| resolution | measure of the clarity of the image; minimum distance two points can be separated and still be distinguished as separate points |
| contrast | difference in brightness between the light and dark areas of an image |
| organelles | membrane-enclosed structures within eukaryotic cells |
| electron microscope | focuses electrons instead of light through the specimen or onto its surface |
| scanning electron microscope | electron beam scans sample surface, excites electrons on sample then have image detected and transmitted on a screen to make it appear 3D |
| transmission electron microscope | observes internal structure of cells by dying parts with heavy metals and passing electrons through an electromagnetic lens to be seen on a monitor |
| cell fractionation | broken cells are put in a tube spun in a centrifuge, then pellets are formed of the various organelles |
| cytosol | semifluid in cells where subcellular components are suspended |
| eukaryotic cell | DNA stored in the nucleus bounded by a double membrane ("true nucleus") |
| prokaryotic cell | DNA stored in not membrane-enclosed nucleoid ("before nucleus") |
| fimbriae | attachment structures on the surface of some prokaryotes |
| nucleoid | region where the cell's DNA is located (not enclosed by a membrane) |
| ribosomes | complexes that synthesize proteins |
| plasma membrane | membrane enclosing the cytoplasm |
| cell wall | rigid structure outside the plasma membrane |
| capsule | jellylike outer coating of many prokaryotes |
| flagella | locomotion organelles of some bacteria |
| cytoplasm | interior of cell |
| flagellum | motility structure present in some animal cells, composed of a cluster of microtubules within an extension of the plasma membrane |
| centrosome | region where the cell's microtubules are initiated; contains a pair of centrioles |
| cytoskeleton | reinforces cell's shape; functions in cell movement; components are made of protein |
| microvilli | projections that increase the cell's surface area |
| peroxisome | organelle with various specialized metabolic functions; produces hydrogen peroxide as a by-product and then converts it to water |
| mitochrondrion | organelle where cellular respiration occurs and most ATP is generated |
| endoplasmic reticulum | network of membranous sacs and tubes; active in membrane synthesis and other synthetic and metabolic processes; has rough (ribosome-studded) and smooth regions |
| nuclear envelope | double membrane enclosing the nucleus; perforated by pores; continuous with ER |
| nucleolus | nonmembranous structure involved in production of ribosomes; a nucleus has one or more nucleoli |
| chromatin | material consisting of DNA and proteins; visible in a dividing cell as individual condensed chromosomes |
| golgi apparatus | organelle active in synthesis, modification, sorting, and secretion of cell products |
| lysosome | digestive organelle where macromolecules are hydrolyzed |
| plasmodesmata | cytoplasmic channels through cell walls that connect the cytoplasms of adjacent cells |
| chloroplast | photosynthetic organelle; converts energy of sunlight to chemical energy stored in sugar molecules |
| central vacuole | prominent organelle in older plant cells; functions include storage, breakdown of waste products, and hydrolysis of macromolecules; enlargement of the vacuole is a major mechanism of plant growth |
| nucleus | contains most of the genes in the eukaryotic cell |
| nuclear lamina | lines the nuclear side of the envelope; a netlike array of protein filaments that maintains the shape of the nucleus by mechanically supporting the nuclear envelope |
| chromosomes | organization of DNA |
| endomembrane system | anything within and including the plasma membrane |
| vesicles | sacs made of membrane for transportation |
| glycoproteins | proteins with carbohydrates covalently bonded to them; often secretory proteins; carbohydrates attached to them by enzymes in the ER lumen |
| transport vesicles | vesicles in transit from one part of the cell to another |
| phagocytosis | when amoebas or unicellular eukaryotes eat by absorbing smaller organisms or food particles |
| vacuoles | large vesicles from ER and golgi; selective in transporting solutes so has a solution different from cytosol |
| food vacuoles | formed by phagocytosis |
| contractile vacuoles | pump excess water out of cell to maintain suitable concentration of ions and molecules inside cell |
| endosymbiont theory | theory that a eukaryotic ancestor cell absorbed a non-photosynthetic prokaryote and formed a symbiotic relationship that ended with cells having mitochondria and the same must have happened with a photosynthetic prokaryote to make chloroplasts |
| cristae | infoldings in the inner membrane of mitochondria |
| mitochondrial matrix | enclosed by mitochondria's inner membrane and stores enzymes, DNA, and ribosomes |
| thylakoids | interconnected sacs in the inner membrane space of chloroplasts |
| granum | stacks of thylakoids |
| stroma | fluid outside of thylakoids that has DNA, ribosomes, and enzymes |
| plastids | a family of plant organelles where chloroplasts come from |
| motor proteins | interact with cytoskeleton for cell motility |
| microtubules | hollow rods constructed from globular proteins called tubulin |
| centrioles | composed of nine sets of triplet microtubules arranged in a ring and located in pairs in the centrosome |
| flagella and cilia | microtubule-containing extensions that project from some cells |
| basal body | anchors cilia and flagella; structurally similar to centriole with microtubules in a 9to pattern |
| dyneins | motor proteins attached along microtubule doublets that bend flagella and cilia |
| microfilaments | thin solid rods built from actin molecules (a globular protein) |
| myosin | motor protein with thicker filaments that interact to cause contraction of muscle cells |
| intermediate filaments | larger than microfilaments and smaller than microtubules; only found in some animals, including vertebrates |
| primary cell wall | secreted by a young plant cell; thin and flexible |
| middle lamella | thin layer rich in sticky polysaccharides called pectins and located between primary walls of adjacent cells |
| secondary cell wall | between plasma membrane and primary wall; strong and durable matrix |
| extracellular matrix | made of glycoproteins and carbohydrate-containing molecules in animal cells |
| collagen | most abundant glycoprotein in ECM; forms strong fibers outside cells (40%) of protein in human body |
| proteoglycans | small core protein with many carbohydrate chains covalently attached |
| fibronectin | bind to cell surface receptor proteins (integrins) built into plasma membrane |
| integrins | position to transmit signals between ECM and cytoskeleton |
| selective permeability | allows some substances to cross more easily than others |
| amphipathic | has both a hydrophilic and hydrophobic region |
| fluid mosaic model | proteins shown in fluid bilayer of phospholipids, associated in long-lasting, specialized patches; continually revised through research |
| integral proteins | penetrate hydrophobic interior of lipid bilayer |
| peripheral proteins | not embedded in bilayer; loosely bound to surface of membrane, to exposed parts of integral proteins |
| glycolipids | when carbohydrates are covalently bonded to proteins (for cell recognition) |
| transport proteins | span membrane and have hydrophilic channels |
| aquaporins | water molecules pass through these channel proteins |
| diffusion | the movement of particles of any substance so that they spread out in available space |
| concentration gradient | the region along which the density of a substance increases or decreases |
| passive transport | diffusion of a substance across a biological membrane; does not expend energy for movement |
| osmosis | when free water diffuses across a selectively permeable barrier to dilute higher concentrations of solutes |
| tonicity | ability of a surrounding solution to cause a cell to gain or lose water |
| isotonic | an environment equal to that of a cell, leading to no net movement of water across the membrane |
| hypertonic | more nonpenetrating solutes, leading to water leaving the cell |
| hypotonic | less nonpenetrating solutes, leading to water coming into the cell |
| osmoregulation | the control of solute concentrations and water balance |
| turgid | very firm; natural state of plant cells when holding back water |
| flaccid | limp, cells become this when in isotonic environments |
| plasmolysis | when a plant cell is in a hypertonic environment and causes the membrane to pull away from the cell wall |
| facilitated diffusion | when polar ions and molecules move across the membrane with the help of transport proteins |
| ion channels | channel proteins that transport ions |
| gated channels | open or close in response to stimulus; ion channels, function as this |
| active transport | moving a solute against its concentration gradient, thus expending energy |
| sodium-potassium pump | exchanges Na+ for K+ across animal cell membrane; ATP transfers phosphate group to transport protein |
| membrane potential | the voltage across a membrane |
| electrochemical gradient | the combination of the concentration gradient and the membrane potential acting on an ion |
| electrogenic pump | a transport protein that generates voltage across a membrane; sodium-potassium pump is main for animals |
| proton pump | main electrogenic pump for plants, fungi, and bacteria; actively transports H+ out of the cell |
| cotransport | a transport protein couples the diffusion of a solute to a second substance moving against its own concentration |
| exocytosis | fusion of vesicles with membrane resulting in cell secretion |
| endocytosis | forms new vesicles from plasma membrane to take in molecules |
| pinocytosis | takes nonspecific kinds or amounts of extracellular fluids into tiny vesicles; have coat protein on the cytoplasmic side |
| receptor-mediated endocytosis | specialized type of pinocytosis where large quantities of specific substances can be collected by receptor sites on proteins in membrane exposed to extracellular fluid (proteins returned later) |
| hormones | chemicals used for long-distance signaling; also called endocrine signaling |
| reception | target cell detects a signaling molecule through the molecule binding to its receptor protein |
| transduction | the conversion of the signal to a form that can cause a specific cellular response |
| signal transduction pathway | a sequence of changes in a series of different molecules |
| response | transduced signal triggers reaction |
| ligand | a molecule that specifically binds to another molecule, often a larger one |
| G protein-coupled receptor | cell-surface transmembrane receptor that works by a G protein |
| G protein | binds energy rich molecule GTP |
| ligand-gated ion channel | membrane receptor with a region that acts as a gate for ions when the receptor takes a certain shape |
| protein kinase | an enzyme that transfers phosphate groups from ATP to a protein; common relay molecule |
| phosphorylation cascade | series of different proteins phosphorylated in turn, returned to inactive form by dephosphorylation cascade |
| protein phosphatases | enzymes that can rapidly remove phosphate groups from proteins |
| second messengers | small, nonprotein, water-soluble molecules or ions that diffuse through the cell in the signaling pathway |
| cyclic AMP | cAMP; cyclic adenosine monophosphate, a common second messenger |
| cell division | reproduction of cells; basis of the continuity of life |
| cell cycle | time of cell's life from its division from the parent cell to its own division into two daughter cells |
| genome | a cell's endowment of DNA |
| chromosomes | what DNA molecules are packaged into to make replication and distribution possible |
| chromatin | the entire complex of DNA and proteins used for building chromosomes |
| somatic cells | any cell that isn't a reproductive cell |
| gametes | reproductive cells |
| sister chromatids | joined copies of the original chromosome |
| centromere | region of the chromosomal DNA where the chromatid is most closely attached to the sister chromatid |
| mitosis | division of genetic material in nucleus |
| cytokinesis | division of cytoplasm |
| mitotic (M) phase | includes mitosis and cytokinesis; shortest part of cell cycle |
| interphase | 90% of cell cycle |
| G1 phase | first gap |
| S phase | synthesis |
| G2 phase | second gap |
| mitotic spindle | begins to form in cytoplasm during prophase; made of fibers from microtubules and associated proteins |
| aster | radial array of short microtubules extending from each centrosome |
| kinetochore | structure made up of proteins that have assembled specific sections of chromosomal DNA at each centromere |
| cleavage | the process that produces cytokinesis |
| cleavage furrow | shallow groove in the cell surface near the metaphase plate |
| cell plate | vesicles from golgi congregate here by microtubules, in the middle of the cell; creates new membrane and wall here |
| binary fission | "division in half"; asexual reproduction of single-celled eukaryotes and the reproduction of prokaryotes |
| origin of replication | specific place on bacterial chromosome where it begins to replicate; copies separate to either end of cell |
| cell cycle control system | cyclically operating molecules in the cell that trigger and coordinate key events in the cell cycle |
| checkpoint | control point in the cell cycle where stop and go signals regulate the cycle |
| G0 phase | a nondividing state of a cell |
| growth factor | a protein released by some cells that stimulates other cells to divide |
| density-dependent inhibition | crowded cells stop dividing |
| anchorage dependence | must be attached to a substratum to divide |
| transformation | cells in culture undergo this when they can divide indefinitely, like cancer cells |
| benign tumor | when a clump of abnormal cells don't have enough genetic and cellular changes to survive at another site |
| malignant tumor | cells whose genetic and cellular changes will let them spread to new tissues and impair organ functionality; this is cancer |
| metastasis | the spread of cancer cells to locations away from their original site |
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cramdel37
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