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Biology Chapter 6-7
| Question | Answer |
|---|---|
| Light Microscope (LM) | visible light is passed through the specimen then through glass lenses. |
| Magnification | ratio of an object's image size to its real size. |
| Resolution | a measure of the clarity of the image; it is the minimum distance two points can be separated and still be distinguished as two points |
| Contrast | accentuates differences in parts of the sample |
| organelles | sub cellular structures that are membrane-enclosed compartments |
| Electron Microscope (EM) | focuses a beam of electrons through the specimen or onto its surface, more powerful, but kills the cells examined |
| cell ultrastructure | the cellular anatomy revealed by an electron microscope |
| Scanning Electron Microscope (SEM) | useful for detailed study of the surface of a specimen. thin gold film excited, results in image of specimen's topography, three-dimensional image |
| Transmission Electron Microscope (TEM) | study the internal ultrastructure of cells. electron bean through thin section of specimen, displaying a pattern of transmitted electrons. Electromagnets used |
| Cytology | study of cell structure |
| Biochemistry | study of molecules and chemical processes of cells |
| Cell Fractionation | takes cells apart and separates major organelles from one another, using the centrifuge. studies cell structure and function. |
| Ultracentrifuges | powerful centrifuges, yielding a pellet with smaller components |
| Nucleus | contains most of the genes in the eukaryotic cell. most conspicuous organelle in eukaryotic cell |
| Nuclear Envelope | encloses the nuclear, separating its contents from the cytoplasm, it is a double membrane perforated by pores |
| Pore Complex | intricate protein structure that lines each pore and plays an important role in the cell by regulating the entry and exit of most proteins and RNAs as well as large complexes of macromolecules |
| Nuclear Lamina | aside from the pores, 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 |
| Nuclear Matrix | a framework of fibers extending throughout the nuclear interior |
| Chromosomes | DNA organized into these discrete units, structures that carry the genetic information, every eukaryotic species has characteristic number. As cell divides, chromatin fibers condense and become thick enough to be distinguished |
| Chromatin | make up chromosomes, is a complex of proteins and DNA |
| Nucleolus | prominent structure within the nondividing nucleus, appears as mass of densely stained granules and fibers adjoining part of the chromatin, proteins are assembled into small ribosomal subunits |
| Cytosol | semifluid, jellylike substance in which organelles and other components are found |
| Eukaryotic cell | most of the DNA is in the nucleus, larger |
| Prokaryotic cell | most of the DNA is concentrated in a region not membrane-enclosed, called the nucleoid |
| Nucleoid | A region in a prokaryotic cell where the DNA is concentrated. |
| Cytoplasm | Interior of a prokaryotic cell |
| Plasma membrane | boundary of every cell, functions as a selective barrier that allows sufficient passage of oxygen, nutrients, and wastes to service the entire cell. |
| Ribosomal RNA | synthesized from instructions in the DNA in the nucleolus |
| Ribosomes | complexes made of ribosomal RNA and protein, the cellular components that carry out protein synthesis. |
| Free ribosomes | suspended in the cytosol, one cytoplasmic locale for building proteins. functions within cytosol |
| Bound ribosomes | attached to the oustide of the endoplasmic reticulum or nuclear envelope, one cytoplasmic locale for building proteins. make proteins destined for insertion in membrane |
| Endomembrane system | made up of different membranes of eukaryotic cell, carries out synthesis of proteins and their transport, metabolism and movement of lipids, and detoxification of poisons. includes nuclear envelope, golgi apparatus, endoplasmic reticulum, lysosomes, etc. |
| Vesicles | when endomembrane system not physically connected, these tiny sacs made of membrane transfer membrane segments |
| Endoplasmic Reticulum | extensive network of membranes, accounting for more than half membrane in many eukaryotic cells. Network of membranous tubules and sacs called cisternae. Separates internal compartment (lumen) from cytosol |
| Smooth ER | outer surface lacks ribosomes. synthesis of lipids, sex hormones, detoxify drugs and poisons, stores calcium ions |
| Rough ER | ribosomes on the outer surface. makes secretory proteins, membrane factory, makes its own membrane phospholipids |
| Glycoproteins | proteins that have carbohydrates covalently bonded to them. the carbohydrates are attached to the proteins in the ER by specialized molecules |
| Transport Vesicles | Vesicles in transit from one part of the cell to the other |
| Golgi apparatus | center of manufacturing, warehousing, sorting, and shipping. products are modified and stored and then sent to other destinations. extensive in cells specialized for secretion |
| cis face of Golgi apparatus | located near the ER, acts as receiving department |
| trans face of Golgi aparatus | gives rise to vesicles, acts as delivering department |
| Cisternal maturation model | the cisternae of the Golgi actually progress forward from the cis to the trans face of the Golgi |
| Lysosome | a membranous sac of hydrolytic enzymes that an animal cell uses to digest macromolecules |
| Phagocytosis | a process where smaller organisms or food particles are eaten by the food vacuole. |
| Autophagy | recycle the cell's own organic material |
| Food Vacuoles | formed by phagocytosis, fuses with a lysosome whose enzymes digest the food |
| Contractile vacuoles | many freshwater protists have this, pump excess water out of the cell, thereby maintaining a suitable concentration of ions and molecules inside the cell |
| Central vacuole | develops by the coalescence of smaller vacuoles, an integral part of a plant's endomembrane system, holds reserves of organic compounds, main repository of inorganic ions, contain pigments, protection, growth |
| Mitochondria | sites of cellular respiration, the metabolic process that generates ATP by extracting energy from sugars, fats, and other fuels with the help of oxygen. found in nearly all eukaryotic cells |
| Chloroplasts | found in plants and algae, the sites of photosynthesis, converting solar energy to chemical energy. |
| Peroxisome | an oxidative organelle that is not part of the endomembrane system, imports its proteins from the cytosol. specialized metabolic compartment that transfers hydrogen from various substrates to oxygen, producing hydrogen peroxide |
| Cristae | the inner membrane of mitochondria is convoluted with these infoldings |
| Mitochondrial matrix | enclosed by an inner membrane, contains many different enzymes as well as the mitochondrial DNA and ribosomes |
| Plastids | a family of closely related plant organelles |
| Thylakoids | Inside the chloroplast, another membranous system in the form of flattened, interconnected sacs |
| Granum | thylakoids are stacked like poker chips in these stacks |
| Stroma | fluid outside the thylakoids, contains the chloroplast DNA and ribosomes, as well as enzymes |
| Glyoxysomes | specialized peroxisomes found in the fat storing tissues of plant seeds, contain enzymes that initiate the conversion of fatty acids to sugar, which is used by seedling |
| Cytoskeleton | a network of fibers extending throughout the cytoplasm, plays a major role in organizing the structures and activities of the cell, composed of microtubules, microfilaments, and intermediate filaments |
| Cell Motility | changes in cell location and more limited movements of parts of the cell. Requires interaction of cytoskeleton with motor proteins |
| Motor Proteins | bring about the bending of cilia and flagella by gripping microtubules within those organisms and sliding them together. |
| Microtubules | larget, hollow rods, wall constructed from a globular protein called tubulin, each is dimer, two subunits, one end accumulates/releases tubulin dimers frequentlier, called the plus end. shape and support cell, tracks along which motor proteins move |
| Centrosome | Microtubules grow out from this region, located near the nucleus and considered a microtubule organizing center. These microtubules function as compression-resisting girders of the cytoskeleton |
| Centrioles | composed of nine sets of triplet microtubules arranged in a ring. within the centrosome, help organize microtubule assembly, not necessary in all eukaryotic cells |
| Flagella | Microtubule-containing extensions that project from cells, longer, limited to just one or a few per cell, undulating motion, snakelike. |
| Cilia | Microtubule-containing extensions that project from cells, occur in large numbers, work like oars, may act as antenna |
| Basal Body | microtubule assembly of flagella or cilia is anchored by this, structurally similar to centriole |
| Dyneins | large motor proteins composed of several polypeptides, responsible for bending movements of the organelle, has two feet that "walk" |
| Microfilaments | solid rods, are also called actin filaments since built from actin, form structural networks, present in all eukaryotic cells |
| Actin | make up microfilaments, a globular protein |
| Cortex | the outer cytoplasmic layer of a cell, given the semisolid consistency of a gel |
| Myosin | Actin filaments arranged parallel to one another along muscle cell, interdigitated with thicker filaments made of this protein, acts as microfilament based motor protein by "walking" |
| Pseudopodia | cellular extensions which extend and contract through the reversible assembly of actin subunits into microfilaments and of microfilaments into networks that convert cytoplasm from a sol to a gel |
| Cytoplasmic streaming | a circular flow of cytoplasm within cells. This movement speeds the distribution of materials within the cell |
| Intermediate Filaments | mid-sized. specialized for bearing tension, diverse class of cytoskeletal elements, each constructed from a different molecular subunit, more permanent fixtures |
| Cell wall | extracellular structure of plant cells that distinguishes them from animal cells. protects the plant cell, maintains shape, prevents excessive uptake of water, hold the plant up against gravity, thicker |
| Primary cell wall | a relatively thin and flexible wall first secreted by a young plant cell, affected by microtubules |
| Middle lamella | a thin layer rich in sticky polysaccharides called pectins, glues adjacent cells together |
| Secondary cell wall | between the plasma membrane and the primary wall, a wall deposited in several laminated layers, has a strong and durable matrix that affords the cell protection and support (e.g. wood) |
| Extracellular matrix (ECM) | made up of glycoproteins secreted by cells, animal cells have this |
| Collagen | forms strong fibers outside the cells, accoutns for about 40% of total protein in body, and makes up most of ECM |
| Proteoglycans | collagen fibers are embedded in a network woven from this. consists of small core protein with many carbohydrate chains attached |
| Fibronectin | cells attached to ECM by other glycoproteins such as this. bind to cell surface receptor proteins called integrins |
| Integrins | built into plasma membrane, spam the membrane and bind on their cytoplasmic side to associated proteins attached to microfilaments of the cytoskeleton. transmit signals between ECM and cytoskeleton |
| Plasmodesmata | cell walls perforated with these channels. connections unify most of the plant into one living continuum. |
| Tight junctions | intercellular junction, plasma membranes of neighboring cells are tightly pressed against each other, bound by specific proteins, tight, prevent leakage (e.g. skin cells) |
| Desmosomes | function like rivets, fastening intercellular junction, cells together into strong sheets, intermediate filaments anchor them. (e.g. muscle tears) |
| Gap Junctions | provide cytoplasmic channels from one cell to an adjacent cell and consist of membrane proteins that intercellular junction, surround a pore through which small molecules may pass (e.g. heart muscle) |
| Selective Permeability | exhibited by plasma membrane, allows some substances to cross it more easily than others, fundamental to life |
| Amphipathic | has both a hydrophilic region and a hydrophobic region, gives the ability for phospholipids to form membranes |
| Fluid Mosaic Model | membrane is a fluid structure with an arrangement of various proteins embedded in or attached to a double layer of phospholipids. |
| Sandwich model | a phospholipid bilayer between two layers of proteins, false. generalized that all membranes of cell are identical (wrong). proteins not soluble in water (not accounted for) |
| Integral Proteins | penetrate the hydrophobic core of the lipid bilayer, one of two major populations of membrane proteins |
| Transmembrane Proteins | integral proteins that span the entire membrane |
| Peripheral proteins | not embedded in the lipid bilayer at all, appendages loosely bound to the surface of the membrane, often to exposed parts of integral proteins |
| Major functions performed by proteins of Plasma Membrane | transport, enzymatic activity, signal transduction, cell-cell recognition, intercellular joining, attachment to the cytoskeleton and extracellular matrix (ECM) |
| Glycolipids | Membrane carbohydrates covalently bonded to lipids |
| Glycoproteins | Membrane carbohydrates covalently bonded to proteins |
| Transport proteins | span the membrane, way that hydrophilic substances can avoid contact with the lipid bilayer by passing through these, specific for the substance it moves |
| Channel proteins | a type of transport protein that functions by having a hydrophilic channel that certain molecules or atomic ions use as a tunnel through the membrane |
| Aquaporins | a type of channel proteins that facilitates the passage of water molecules through the membrane, in great quantities. |
| Carrier proteins | a type of transport protein, holds on to passengers and changes shape in a way that shuttles them across the membrane. |
| Diffusion | a result of thermal motion, the movement of molecules of any substance so that they spread out evenly into the available space. Each molecule moves randomly, yet the population of a molecule may have a direction. |
| Concentration gradient | the region along which the density of a chemical substance decreases; the way a substance diffuses |
| Passive transport | the cell does not have to expend energy to make it happen, diffusion of a substance across a biological membrane. |
| Osmosis | diffusion of water across a selectively permeable membrane |
| Tonicity | the ability of a solution to cause a cell to gain or lose water, depends on its concentration of solutes that cannot cross the membrane relative to that inside the cell |
| Isotonic | a solution has the same concentration as that inside the cell |
| Hypertonic | a solution has more nonpenetrating solutes as that inside a cell. causes the cell to lose water to environment |
| Hypotonic | a solution has less nonpenetrating solutes as that inside a cell. causes the cell to gain water from environment and possibly lyse (burst) |
| Osmoregulation | the control of water balance, organisms without cell walls develop this to defend against the environment, (e.g. a contractile vacuole) |
| Turgid | very firm, the healthy state for most plant cells; the relatively inelastic wall exerts a back pressure on the cell that opposes further water uptake |
| Flaccid | when a plant's cells are in an isotonic solution, no net tendency for water to enter |
| Plasmolysis | if cell is immersed in a hypertonic environment, will lose water and shrivel, as its plasma membrane pulls away from the wall in this process. leads to plant death |
| Facilitated Diffusion | polar molecules and ions impeded by the lipid bilayer diffuse passibely with the help of transport proteins. This phenomenon is called this. |
| Ion channels | a group of channel proteins, many of which function as gated channels |
| Gated Channels | open and close in response to a stimulus, which may be electrical or chemical |
| Active transport | pumping a solute across a membrane against its gradient, expending energy. transport proteins involved are all carrier proteins |
| Sodium-potassium pump | a transport system which exchanged sodium for potassium across the plasma membrane, by ATP transferring its terminal phosphate group directly to the transport protein. form of active transport |
| Electrochemical gradient | the combination of the two forces that drive the diffusion of ions across a membrane : chemical force (concentration gradient) and electrical force (membrane potential) |
| Membrane potential | the voltage across a membrane, the inside of the cell is negative relative to the outside. |
| Electrogenic pump | a transport protein that generates voltage across a membrane, the main one is the sodium-potassium pump |
| Proton pump | the main electrogenic pump of plants, fungi, and bacteria; actively transports hydrogen ions out of the cell |
| Cotransport | a mechanism that allows a single ATP-powered pump to transport a specific solute to indirectly drive the active transport of several other solutes; pumping water uphill so it performs work as it comes back down; the downhill part is this |
| Exocytosis | the cell secretes certain biological molecules by the fusion of vesicles with the plasma membrane; used to export products |
| Endocytosis | the cell takes in biological molecules and particulate matter by forming new vesicles from the plasma membrane; three types |
| Phagocytosis | "cellular eating", a cell engulfs a particle by wrapping pseudopodia around it and packaging it within a membrane-enclosed sac large enough to be a vacuole. digested after fusing with lysosome |
| Pinocytosis | "cellular drinking", cell gulps droplets of extracellular fluid into tiny vesicles; used to obtain molecules dissolved in droplets, nonspecific in substances it transports |
| Receptor-mediated endocytosis | enables the cell to acquire bulk quantities of specific substances, even though those substances may not be concentrated in the extracellular fluid. proteins are clustered in coated pits, lined by fuzzy layer of coat proteins |
| Ligands | low density lipoproteins act as this; term for any molecule that binds specifically to a receptor site on another molecule. |
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