AP Bio Chapter 4; Cells
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39 terms
Terms | Definitions |
|---|---|
 cell wall | A relatively rigid structure that encloses cells of plants, fungi, many protists, and most prokaryotes. Gives these cells their shape and limits their expansion in hypotonic media. |
| Centriole | (sen´ tree ole) A paired organelle that helps organize the microtubules in animal and protist cells during nuclear division. |
| Chloroplast | [Gk. kloros: green + plast: a particle] An organelle bounded by a double membrane containing the enzymes and pigments that perform photosynthesis. Chloroplasts occur only in eukaryotes. |
| Cilium | (sil´ ee um) (plural: cilia) [L.: eyelash] Hairlike organelle used for locomotion by many unicellular organisms and for moving water and mucus by many multicellular organisms. Generally shorter than a flagellum. |
| Collagen | [Gk. kolla: glue] A fibrous protein found extensively in bone and connective tissue. |
| Cytoplasm | The contents of the cell, excluding the nucleus. |
| Cytoskeleton | The network of microtubules and microfilaments that gives a eukaryotic cell its shape and its capacity to arrange its organelles and to move. |
| Cytosol | The fluid portion of the cytoplasm, excluding organelles and other solids. |
| endomembrane system | Endoplasmic reticulum plus Golgi apparatus; also lysosomes, when present. A system of membranes that exchange material with one another. |
| endoplasmic reticulum | (ER) [Gk. endo: within + L. plasma: form + L. reticulum: net] A system of membranous tubes and flattened sacs found in the cytoplasm of eukaryotes. Exists in two forms: rough ER, studded with ribosomes; and smooth ER, lacking ribosomes. |
| Endosymbiosis | [Gk. endo: within + sym: together + bios: life] Two species living together, with one living inside the body (or even the cells) of the other. |
| endosymbiotic theory | The theory that the eukaryotic cell evolved via the engulfing of one prokaryotic cell by another. |
| eukaryotes (Eukarya) | [4] Organisms made up of one or more complex cells in which the genetic material is contained in nuclei. Contrast with archaeans [3] and bacteria [2]. |
| extracellular matrix | In animal tissues, a material of heterogeneous composition surrounding cells and performing many functions including adhesion of cells. |
| Flagellum | (fla jell´ um) (plural: flagella) [L. flagellum: whip] Long, whiplike appendage that propels cells. Prokaryotic flagella differ sharply from those found in eukaryotes. |
| Glyoxysome | (gly ox´ ee soam) An organelle found in plants, in which stored lipids are converted to carbohydrates. |
| Golgi apparatus | (goal´ jee) A system of concentrically folded membranes found in the cytoplasm of eukaryotic cells; functions in secretion from cell by exocytosis. |
| intermediate filaments | Cytoskeletal component with diameters between the larger microtubules and smaller microfilaments. |
| lysosome | A membrane-enclosed organelle found in eukaryotic cells (other than plants). Lysosomes contain a mixture of enzymes that can digest most of the macromolecules found in the rest of the cell. |
| Microfilament | Minute fibrous structure generally composed of actin found in the cytoplasm of eukaryotic cells. They play a role in the motion of cells. |
| Microtubules | Minute tubular structures found in centrioles, spindle apparatus, cilia, flagella, and cytoskeleton of eukaryotic cells. These tubules play roles in the motion and maintenance of shape of eukaryotic cells. |
| Mitochondrion | (my´ toe kon´ dree un) [Gk. mitos: thread + chondros: grain] An organelle in eukaryotic cells that contains the enzymes of the citric acid cycle, the respiratory chain, and oxidative phosphorylation. |
| nuclear envelope | The surface, consisting of two layers of membrane, that encloses the nucleus of eukaryotic cells. |
| nuclear lamina | A meshwork of fibers on the inner surface of the nuclear envelope. |
| nuclear pore complex | A protein structure situated in nuclear pores through which RNA and proteins enter and leave the nucleus. |
| Nucleoid | (new´ klee oid) The region that harbors the chromosomes of a prokaryotic cell. Unlike the eukaryotic nucleus, it is not bounded by a membrane. |
| Nucleolus | (new klee´ oh lus) A small, generally spherical body found within the nucleus of eukaryotic cells. The site of synthesis of ribosomal RNA. |
| Nucleus | (new´ klee us) [L. nux: kernel or nut] (1) In cells, the centrally located compartment of eukaryotic cells that is bounded by a double membrane and contains the chromosomes. (2) In the brain, an identifiable group of neurons that share common characteristics or functions. |
| Organelles | (or gan els´) Organized structures found in or on eukaryotic cells. Examples include ribosomes, nuclei, mitochrondria, chloroplasts, cilia, and contractile vacuoles. |
| Peroxisome | An organelle that houses reactions in which toxic peroxides are formed. The peroxisome isolates these peroxides from the rest of the cell. |
| plasma membrane | The membrane that surrounds the cell, regulating the entry and exit of molecules and ions. Every cell has a plasma membrane. |
| Plasmodesm | A cytoplasmic strand connecting two adjacent plant cells |
| Prokaryotes | (pro kar´ ry otes) [L. pro: before + Gk. karyon: kernel, nucleus] Organisms whose genetic material is not contained within a nucleus: the bacteria and archaea. Considered an earlier stage in the evolution of life than the eukaryotes. |
| Proteoglycan | A glycoprotein containing a protein core with attached long, linear carbohydrate chains. |
| Resolution | Of an optical device such as a microscope, the smallest distance between two lines that allows the lines to be seen as separate from one another. |
| Ribosome | A small organelle that is the site of protein synthesis. |
| surface area to volume ratio | For any cell, organism, or geometrical solid, the ratio of surface area to volume; this is an important factor in setting an upper limit on the size a cell or organism can attain. |
| Thylakoid | (thigh la koid) [Gk. thylakos: sack or pouch] A flattened sac within a chloroplast. Thylakoid membranes contain all of the chlorophyll in a plant, in addition to the electron carriers of photophosphorylation. Thylakoids stack to form grana. |
| Vacuole | (vac´ yew ole) [Fr.: small vacuum] A liquid-filled, membrane-enclosed compartment in cytoplasm; may function as digestive chambers, storage chambers, waste bins. |
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