AP Biology Chapter 4 & 5a Flashcards
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hlrbiology on October 24, 2009
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70 terms
Terms | Definitions |
|---|---|
 basal body | A eukaryotic cell organelle consisting of microtubule triplets; may organize the microtubule assembly of a cilium or flagellum; structurally identical to a centriole. |
| cell theory | The theory that all living things are composed of cells and that all cells come from other cells. |
| cell wall | A protective layer external to the plasma membrane in plant cells, bacteria, fungi, and some protists; protects the cell and helps maintain its shape. |
| cellular metabolism | The chemical activities of cells. |
| central vacuole | A membrane-enclosed sac occupying most of the interior of a mature plant cell, having diverse roles in reproduction, growth, and development. |
| centriole | A structure in an animal cell composed of cylinders of microtubule triplets arranged in a 9 and 0 pattern; involved in animal cell division. |
| chloroplast | An organelle found in plants and photosynthetic protists that absorbs sunlight and uses it to drive the synthesis of organic molecules (sugars) from carbon dioxide and water. |
| chromatin | The complex of DNA and proteins that constitutes eukaryotic chromosomes. |
| chromosome | A threadlike, gene-carrying structure found in the nucleus of a eukaryotic cell and most visible during mitosis and meiosis; also, the main gene-carrying structure of a prokaryotic cell. |
| cilia | A short cellular appendage specialized for locomotion formed from a core of nine outer doublet microtubules and two single microtubules covered by the cell's plasma membrane. |
| cristae | Infolding of the inner membrane of a mitochondrion in which is embedded the electron transport chain and the enzyme catalyzing the synthesis of ATP. |
| cytoplasm | Everything inside a cell between the plasma membrane and the nucleus; consists of a semifluid medium and organelles. |
| cytoskeleton | A network of protein fibers in the cytoplasm of a eukaryotic cell; includes microfilaments, intermediate filaments, and microtubules. |
| electron microscope | An instrument that focuses an electron beam through, or onto the surface of, a specimen; achieves a hundredfold greater resolution than a light microscope. |
| endomembrane system | A network of membranes inside and around a eukaryotic cell, related either through direct physical contact or by the transfer of membranous vesicles. |
| endoplasmic reticulum | An extensive membranous network in a eukaryotic cell, continuous with the outer nuclear membrane and composed of ribosome-studded (rough) and ribosome-free (smooth) regions. |
| endosymbiosis | A process by which the mitochondria and chloroplasts of eukaryotic cells probably evolved from symbiotic associations between small prokaryotic cells living inside larger cells. |
| eukaryotic cell | A type of cell that has a membrane-enclosed nucleus and other membrane-enclosed organelles. All organisms except bacteria and archaea are composed of these types of cells. |
| extracellular matrix | A substance in which the cells of an animal tissue are embedded; consists of protein and polysaccharides. |
| flagellum | A long cellular appendage specialized for locomotion. The appendages of prokaryotes and eukaryotes differ in both structure and function. In eukaryotes, they have a 9 + 2 arrangement of microtubules covered by the cell's plasma membrane. |
| glycoprotein | A macromolecule consisting of one or more polypeptides linked to short chains of sugars (carbohydrates). |
| Golgi apparatus | An organelle in eukaryotic cells consisting of stacks of membranous sacs that modify, store, and ship products of the endoplasmic reticulum. |
| granum | A stack of hollow disks formed of thylakoid membrane in a chloroplast; sites where light energy is trapped by chlorophyll and converted to chemical energy during the light reactions of photosynthesis. |
| integrin | A transmembrane protein that interconnects the extracellular matrix and the cytoskeleton. |
| intermediate filament | An intermediate-sized protein fiber that is one of the three main kinds of fibers making up the cytoskeleton of eukaryotic cells; ropelike, made of fibrous proteins. |
| intermembrane space | One of the two fluid-filled internal compartments of the mitochondrion. The intermembrane space is the narrow region between the inner and outer membranes. |
| light microscope | An optical instrument with lenses that refract (bend) visible light to magnify images and project them into a viewer's eye or onto photographic film. |
| lysosome | A digestive organelle in eukaryotic cells; contains hydrolytic enzymes that digest the cell's food and wastes. |
| microfilament | The thinnest of the three main kinds of protein fibers making up the cytoskeleton of a eukaryotic cell; a solid, helical rod composed of the globular protein actin. |
| micrograph | A photograph taken through a microscope. |
| microtubule | The thickest of the three main kinds of fibers making up the cytoskeleton of a eukaryotic cell; a straight, hollow tube made of globular proteins called tubulins; form the basis of the structure and movement of cilia and flagella. |
| mitochondrial matrix | The fluid contained within the inner membrane of a mitochondrion. |
| mitochondrion | An organelle in eukaryotic cells where cellular respiration occurs. Enclosed by two concentric membranes, it is where most of the cell's ATP is made. |
| nuclear envelope | A double membrane, perforated with pores, which encloses the nucleus and separates it from the rest of the eukaryotic cell. |
| nucleoid | A dense region of DNA in a prokaryotic cell. |
| nucleolus | A structure within the nucleus of a eukaryotic cell where ribosomal RNA is made and assembled with proteins imported from the cytoplasm to make ribosomal subunits. |
| nucleus | The genetic control center of a eukaryotic cell. |
| organelle | A membrane-enclosed structure with a specialized function within a cell. |
| peroxisome | An organelle containing enzymes that transfer hydrogen from various substrates to oxygen, producing and then degrading hydrogen peroxide. |
| plasma membrane | The membrane that sets a cell off from its surroundings and acts as a selective barrier to the passage of ions and molecules into and out of the cell; consists of a phospholipid bilayer in which are embedded molecules of protein and cholesterol. |
| plasmodesma | An open channel in a plant cell wall through which strands of cytoplasm connect from adjacent cells. |
| prokaryotic cell | A type of cell lacking a membrane-enclosed nucleus and other membrane-enclosed organelles; found only in the domains Bacteria and Archaea. |
| ribosome | A cell structure consisting of RNA and protein organized into two subunits and functioning as the site of protein synthesis in the cytoplasm. The subunits are constructed in the nucleolus. |
| rough ER | A network of interconnected membranous sacs in a eukaryotic cell's cytoplasm; covered with ribosomes that make membrane proteins and secretory proteins. |
| scanning electron microscope | A microscope that uses an electron beam to study the surface architecture of a cell or other specimen. |
| smooth ER | A network of interconnected membranous tubules in a eukaryotic cell's cytoplasm; lacks ribosomes. |
| stroma | The fluid of the chloroplast surrounding the thylakoid membrane; involved in the synthesis of organic molecules from carbon dioxide and water; Sugars are made in this area by the enzymes of the Calvin cycle. |
| thylakoid | One of a number of disk-shaped membranous sacs inside a chloroplast; contain chlorophyll and the enzymes of the light reactions of photosynthesis; A stack of these sacs are called a granum. |
| transmission electron microscope | A microscope that uses an electron beam to study the internal structure of thinly sectioned specimens. |
| transport vesicle | A tiny membranous sac in a cell's cytoplasm carrying molecules produced by the cell; buds from the endoplasmic reticulum or Golgi and eventually fuses with another membranous organelle or the plasma membrane, releasing its contents. |
| vacuole | A membrane-enclosed sac that is part of the endomembrane system of a eukaryotic cell, having diverse functions (such as food storage). |
| active transport | The movement of a substance across a biological membrane against its concentration gradient, aided by specific transport proteins and requiring input of energy (often as ATP). |
| aquaporin | A transport protein in the plasma membrane of some plant or animal cells that facilitates the diffusion of water across the membrane (through osmosis). |
| concentration gradient | An increase or decrease in the density of a chemical substance in an area; substances tend to move from where they are more concentrated to where they are less concentrated. |
| diffusion | The spontaneous tendency of a substance to move down its concentration gradient from where it is more concentrated to where it is less concentrated. |
| endocytosis | Cellular uptake of molecules or particles via formation of new vesicles from the plasma membrane. |
| exocytosis | The movement of materials out of the cytoplasm of a cell by the fusion of vesicles with the plasma membrane. |
| facilitated diffusion | The passage of a substance through a specific transport protein across a biological membrane down its concentration gradient. |
| fluid mosaic | A description of membrane structure, depicting a cellular membrane as a mosaic of diverse protein molecules embedded in a fluid bilayer made of phospholipid molecules. |
| hypertonic solution | In comparing two solutions, the one with the greater concentration of solutes; cells in such a solution will lose water to their surroundings. |
| hypotonic solution | In comparing two solutions, the one with the lower concentration of solutes; cells in such a solution will take up water from their surroundings. |
| isotonic solution | A solution having the same solute concentration as another solution, thus having no effect on passage of water in or out of the cell. |
| osmoregulation | Method by which organisms regulate solute concentrations and balance the gain and loss of water. |
| osmosis | The diffusion of water across a selectively permeable membrane. |
| passive transport | The diffusion of a substance across a biological membrane, without any input of energy. |
| phagocytosis | Cellular "eating"; a type of endocytosis whereby a cell engulfs macromolecules, other cells, or particles into its cytoplasm. |
| pinocytosis | Cellular "drinking"; a type of endocytosis in which the cell takes fluid and dissolved solutes into small membranous vesicles. |
| receptor-mediated endocytosis | The movement of specific molecules into a cell by the inward budding of membranous vesicles. The vesicles contain proteins with receptor sites specific to the molecules being taken in. |
| selective permeability | A property of biological membranes that allows some substances to cross more easily than others and blocks the passage of other substances altogether. |
| tonicity | The ability of a solution surrounding a cell to cause that cell to gain or lose water. |
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