AP Biology Cell Structure and Function
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Created by:
lizroxfrench on May 7, 2011
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Description:
Organelles, Cell structure & function, movement of substances
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50 terms
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|---|---|
 nucleus | contains nuclear envelope, DNA (spread out w/in this as the threadlike matrix chromatin) |
| Ribosome | manufactured in the nucleus; consists of RNA molecs and proteins; in the cytoplasm, this assists in the assembly of amino acids into proteins |
| Endoplasmic Reticulum (ER) | stacks of flattened sacs involved in the production of various materials; appear as a series of maze-like channels in cross section; when ribosomes are present, it creates glycoproteins |
| Smooth ER | without ribosomes; responsible for various activities, including the synthesis of lipids andhormones |
| Golgi Apparatus | group of flattened sacs arranged like a stack of bowls; modify and package proteins and lipids into vesicles; vesicles often migrate to and merge with the plasma membrane |
| Vesicles | small, sphericaly shaped sacs that bud from the outside surface of the Golgi apparatus; often migrate to and merge with the plasma membrane, releasing their contens to the outside of the cell |
| Lysosomes | vesicles from a Golgi apparatus that contain digestive enzymes; break down food, cellular debris, and foreign invaders such as bacteria; a low pH is favorable;do NOT occur in PLANT cells |
| Peroxisomes | break down various substances, including hydrogen peroxide (H202), fatty acids, and amino acids; common in liver and kidney cells; in plant cells, these modify by-products of photorespiration |
| Mitochondria | carry out aerobic respiration (energy-in the form of ATP- is obtained from carbohydrates) |
| Chloroplasts | carry out photosynthesis |
| Microtubules | made of protein tubulin; provide support and motility for cellular activites; found in the spindle apparatus |
| Intermediate filaments | provide support for maintaining the shape of the cell |
| Microfilaments | made of the protein actin; involved in cell motility; found in muscles cells and in cells that move by changing shapes, such as phagocytes (WBCs attacking bacteria) |
| Flagella | structures that protrude from the cell membrane; long, few, move in a snakelike motion; 9+2 array; Ex: propels sperm |
| Cilia | structures that protrude from the cell membrane; short, many, move with a back and forth movement; 9+2 array; Ex: line the resp. tract and sweep away debris |
| 9+2 arrangement | nine pairs (doublets) of microtubulesarranged in a circle surrounding a pair of microtubules |
| Centrioles | microtubule organizing centers; pair (enclosed in a centrosome) are located outside the nuclear envelope, gives rise to the microtubules that make up the spindle apparatus used during cell division; nine triples of microtubules arranged in a circle; PLANTS LACK THESE |
| Basal bodies | microtubule organizing centers; at the base of each flagellum and cillium and appear to organize their development; 9 triplets of microtubules arranged in a circle; lower plants (mosses and ferns) with MOTILE sperm have these |
| transport vesicles | move materials b/w organelles or between organelles and the plasma membrane |
| food vacuoles | temporary receptacles of nutrients; often merge with lysosomes, whose digesitve enzymes break down the food |
| Storage vacuoles | in plants store starch, pigments, and toxic substances |
| central vacuoles | large bodies occupying most of the interior of certain plant cells; when fully filled, they exert turgor pressure on the cell walls, thus maintaining the rigidity in the cell; store nutrients and carry out functions otherwise assumed by lysosomes in animal cells |
| contracile vacuoles | specialized organelles in single-celled organisms that collect and pump excess water out of the cell |
| cell walls | found in plants, fungi, protists, and bacteria; develop outside the plasma membrane and provide support for the cell; in plants, it consists mainly of cellulose |
| extracellular matrix | found in animals in the area b/w adjacent cells; occupied by fibrous structural proteins, adhesion proteins, and polysaccharides; provides mechanical support and helps bind adjacent cells together |
| anchoring junctions | protein attachments between adjacent ANIMAL cells |
| Desmosome | kind of anchoring junction; consists of proteins that bind adjacent cells together, providing mech. stability to tissues; associated w/protein filaments that extend into the interior of the cell and serve to hold cellular strucures together |
| tight junctions | tightly stitched seams b/w ANIMAL cells; completely encircles each cell, producing a seal that prevents the passage of materials b/w cells |
| Communicating junctions | passageways b/w cells that allow the transfer of chemical or electrical signals |
| gap junctions | narrow tunnels between ANIMAL cells; consist of connexins (proteins); prevent the cytoplasms of each cell from mixing but allow the passage of ions and small molecs; allow communication b/w cells thru exchange of materials or thru the tranismission of elec. impulses; essentially channel proteins of two adjacents cells that are closely aligned |
| Plasmodesmata | narrow channels between PLANT cells; a narrow tube of ER surrounded by cytoplasm and the plasma membrane passes thru the channel; material exhange occurs thru the cytoplasm surrounding the demotubule |
| Selectively permeable membrane | allows onliy specific substances to pass |
| hypertonic | when there is a higher concentration of solutes |
| hypotonic | when there is a lower concentration of solutes |
| isotonic | when there is an equal concentration of solutes |
| Bulk flow | collective movement of substances in the same direction in response to a force or pressure; Ex: blood moving through a blood vessel |
| Passive Transport | movement of substances from region sof higher to lower concentrations (DOWN a concentration gradient) and do not require expenditure of energy |
| Diffusion | net movement of substances from an area of higher concentration to an area of lower concentration; this movment occurs as a result of the random and constant motion characteristic of all molecules, motion that is independent from the motion of other molecs; a state of equilibrium is attained where molecs are uniformly distributed but continue to move randomly |
| osmosis | diffusion of water molecs across a selectively permeable membrane |
| turgor pressure | osmotic pressure that develops when water enters the cells of plants and microorganisms |
| Dialysis | diffusion of solutes across a selectively permeable membrane; when different solutes are separated by a selectively permeable membrane |
| Plasmolysis | movement of water out of a cell that results in the collapse of the cell |
| facilitated diffusion | diffusion of solutes or water through channel proteins in the plasma membrane; water can pass thru the plasma membrane w/o the aid of specialized proteins, but aquaporins increase the rate of transfer by this |
| Countercurrent exchange | diffusion of substances b/w two regions in which substances are moving by bulk flow in opposite directions; Ex: fish gills-the direction of water flow is opposite to the flow of blood in the blood vessels... diffusion of O2 is maximized because the relative motion of the molecs b/w the two regions is increased and because the concen. grad. b/w the two regions remain constant |
| Active Transport | movement of solutes against a gradient and requires the expenditure of energy (usually ATP); transport proteins in the plasma membrane transfer solutes such as small ions, amino acids, adn monosaccharides across the membrane |
| Exocytosis | process of vesicles fusing with the plamsa membrane and releasing their contents to the outside of the cell |
| Endocytosis | captureof a substance outside the ell when the plamsa membrane merges to engulf it; enters the cytoplasm enclosed in a vesicle |
| Phagocytosis | "cell eating"; undissolved material enters the cell; p.m. wraps around the solid material and engulfs it; ex: WBCs |
| Pinocytosis | "cell drinking"; dissolved substances enter the cell; p.m. folds inward to form a channel allowing liquid to enter; p.m. closes off the channel, encircling the liquid inside a vesicle |
| Receptor-mediated endocytosis | specific molecules in the fluid surrounding the cell bind to specialized receptors that conecntrate in coated pits in the p.m. |
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