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Biology chapt 4
Biology chapter 4
| Term | Definition |
|---|---|
| cell | The smallest unit of life that displays all the properties of life; composed of cytoplasm surrounded by a plasma membrane. |
| cell theory | One of the major theories of biology, which states that all organisms are made up of cells; cells are capable of self-reproduction and come only from preexisting cells. |
| surface-area-to-volume ratio | Ratio of a cell’s outside area to its internal volume; the relationship limits the maximum size of a cell. |
| prokaryotic cell | Cells that generally lack a membrane-bound nucleus and organelles; the cell type within the domains Bacteria and Archaea. |
| eukaryotic cell (eukaryote) | Type of cell that has a membrane-bound nucleus and membranous organelles; found in organisms within the domain Eukarya. |
| bacillus | A rod-shaped bacterium; also a genus of bacteria, Bacillus. |
| coccus | A spherical-shaped bacterium. |
| spirillum (pl., spirilla) | Long, rod-shaped bacterium that is twisted into a rigid spiral; if the spiral is flexible rather than rigid, it is called a spirochete. |
| cell envelope | In a prokaryotic cell, the portion composed of the plasma membrane, the cell wall, and the glycocalyx. |
| plasma membrane | Membrane surrounding the cytoplasm that consists of a phospholipid bilayer with embedded proteins; functions to regulate the entrance and exit of molecules from cell. |
| cell wall | Cellular structure that surrounds a plant, protistan, fungal, or bacterial cell and maintains the cell’s shape and rigidity; composed of polysaccharides. |
| glycocalyx | Gel-like coating outside the cell wall of a bacterium. If compact, it is called a capsule; if diffuse, it is called a slime layer. |
| capsule | A form of glycocalyx that consists of a gelatinous layer; found in blue-green algae and certain bacteria. |
| cytoplasm | Region of a cell between the nucleus, or the nucleoid region of a bacterium, and the plasma membrane; contains the organelles of the cell. |
| nucleoid | Region of prokaryotic cells where DNA is located; it is not bound by a nuclear envelope. |
| plasmid | Extrachromosomal ring of accessory DNA in the cytoplasm of prokaryotes. |
| ribosome | Site of protein synthesis in a cell; composed of proteins and ribosomal RNA (rRNA). |
| cyanobacterium (pl., cyanobacteria) | Photosynthetic bacterium that contains chlorophyll and releases oxygen; formerly called a blue-green alga. |
| thylakoid | Flattened sac within a granum of a chloroplast; membrane contains chlorophyll; location where the light reactions of photosynthesis occur. |
| flagellum (pl., flagella) | Long, slender extension used for locomotion by some bacteria, protozoans, and sperm. |
| fimbria (pl., fimbriae) | Small, bristlelike fiber on the surface of a bacterial cell, which attaches bacteria to a surface; also fingerlike extension from the oviduct near the ovary. |
| conjugation pilus (pl., conjugation pili) | In a bacterium, elongated, hollow appendage used to transfer DNA to other cells. |
| organelle | Small, membranous structures in the cytoplasm having a specific structure and function. |
| endosymbiotic theory | Explanation of the evolution of eukaryotic organelles by phagocytosis of prokaryotes. |
| vesicle | Small, membrane-bound sac that stores substances within a cell. |
| cytoskeleton | Internal framework of the cell, consisting of microtubules, actin filaments, and intermediate filaments. |
| Nucleus | Command center of cell |
| Nuclear envelope | Double membrane with nuclear pores that encloses nucleus. |
| Chromatin | Diffuse threads containing DNA and protein |
| Nucleolus | Region that produces subunits of ribosomes. |
| Endoplasmic reticulum | Protein and lipid metabolism. |
| Rough ER | studded with ribosomes that synthesize proteins. |
| Smooth ER | Lacks ribosomes, synthesize lipid molecules. |
| Peroxisome | Vesicle that is involved in fatty acid metabolism. |
| Ribosomes | Particles that carry out protein synthesis. |
| Polyribosomes | Stiring of ribosomes simultaneously synthesizing same protein. |
| Mitochondrion | Organelle that carries out cellular respiration producing ATP molecules. |
| Golgi Apparatus | Processes, packages, and secretes modifies proteins. |
| Cytoplasm | Semifluid matrix outside nucleus that contains organelles. |
| Lysosome | Vesicle that digests macromolecules and even cell parts. |
| Centrosome | Microtubule orgaizing center that contains a pair of centrioles. |
| Centrioles | Short cylinders of microtubules. |
| Actin Filaments | Protein fibers that play a role in cell division and shape. |
| Intermediate Filaments | Protein fibers that provide stability of shape. |
| Microtubules | Protein cylinders that move organelles. |
| Cytoskeleton | Maintains cell shape and assists movement of cell parts. |
| Plasma Membrane | Outer surface that regulates entrance and exit of molecules. |
| Nuclear Pore | Permits passage of proteins into nucleus and ribosomal subunits out of nucleus. |
| Centrosome (plant) | Microtubule organizing center (lacks centroioles). |
| cell wall | Outer surface that shapes, supports, and protects cell. |
| Plasma Membrane (plant) | Surrounds cytoplasm, and regulates entrance and exit of molecules. |
| Chloroplast | Carries out photosynthesis, producing sugars. |
| Central Vacuole | Large, fluid-filled sac that stores metaboties and helps maintain tugor pressure. |
| nucleus | Membrane-bound organelle within a eukaryotic cell that contains chromosomes and controls the structure and function of the cell. |
| nucleoplasm | Semifluid medium of the nucleus containing chromatin. |
| chromatin | Network of DNA strands and associated proteins observed within a nucleus of a cell. |
| Chromosomes | The structure that transmits the genetic material from one generation to the next; composed of condensed chromatin; each species has a particular number of chromosomes that is passed on to the next generation. |
| gene | Unit of heredity existing as alleles on the chromosomes; in diploid organisms, typically two alleles are inherited—one from each parent. |
| nucleolus | Dark-staining, spherical body in the nucleus that produces ribosomal subunits. |
| nuclear envelope | Double membrane that surrounds the nucleus in eukaryotic cells and is connected to the endoplasmic reticulum; has pores that allow substances to pass between the nucleus and the cytoplasm. |
| nuclear pore | Opening in the nuclear envelope that permits the passage of proteins into the nucleus and ribosomal subunits out of the nucleus. |
| ribosome | Site of protein synthesis in a cell; composed of proteins and ribosomal RNA (rRNA). |
| polyribosome | String of ribosomes simultaneously translating regions of the same mRNA strand during protein synthesis. |
| endomembrane system | Cellular system that consists of the nuclear envelope, endoplasmic reticulum, Golgi apparatus, and vesicles. |
| endoplasmic reticulum (ER) | System of membranous saccules and channels in the cytoplasm, often with attached ribosomes. |
| rough ER (endoplasmic reticulum) | Membranous system of tubules, vesicles, and sacs in cells; has attached ribosomes. |
| smooth ER (endoplasmic reticulum) | Membranous system of tubules, vesicles, and sacs in eukaryotic cells; site of lipid synthesis; lacks attached ribosomes |
| golgi apparatus | Organelle consisting of sacs and vesicles that processes, packages, and distributes molecules about or from the cell. |
| lysosome | Membrane-bound vesicle that contains hydrolytic enzymes for digesting macromolecules and bacteria; used to recycle worn-out cellular organelles. Tay-Sachs disease |
| peroxisome | peroxisome Enzyme-filled vesicle in which fatty acids and amino acids are metabolized to hydrogen peroxide that is broken down to harmless products. |
| vacuole | Membrane-bound sac, larger than a vesicle; usually functions in storage and can contain a variety of substances. In plants, the central vacuole fills much of the interior of the cell. |
| central vacuole | In a plant cell, a large, fluid-filled sac that stores metabolites. During growth, it enlarges, forcing the primary cell wall to expand and the cell surface-area-to-volume ratio to increase. |
| chloroplast | Membrane-bound organelle in algae and plants with chlorophyll-containing membranous thylakoids; where photosynthesis takes place. |
| mitochondria (sing., mitochondrion) | Membrane-bound organelle in which ATP molecules are produced during the process of cellular respiration. |
| stroma | Region within a chloroplast that surrounds the grana; contains enzymes involved in the synthesis of carbohydrates during the Calvin cycle of photosynthesis. |
| thylakoid | Flattened sac within a granum of a chloroplast; membrane contains chlorophyll; location where the light reactions of photosynthesis occur. |
| granum (pl., grana) | Stack of chlorophyll-containing thylakoids in a chloroplast. |
| plastid | Organelle of plants and algae that is bound by a double membrane and contains internal membranes and/or vesicles (i.e., chloroplasts, chromoplasts, leucoplasts). |
| cristae (sing., crista) | Short, fingerlike projections formed by the folding of the inner membrane of mitochondria. |
| matrix | Unstructured, semifluid substance that fills the space between cells in connective tissues or inside organelles. |
| actin filament | Component of the cytoskeleton; plays a role in the movement of the cell and its organelles; a protein filament in a sarcomere of a muscle, its movement shortens the sarcomere, yielding muscle contraction. |
| Intermediate filaments | Ropelike assemblies of fibrous polypeptides in the cytoskeleton that provide support and strength to cells; so called because they are intermediate in size between actin filaments and microtubules. |
| microtubule | Small, cylindrical organelle composed of tubulin protein around an empty central core; present in the cytoplasm, centrioles, cilia, and flagella. |
| centrosome | Central microtubule organizing center of cells. In animal cells, it contains two centrioles. |
| centriole | Cell structure, existing in pairs, that occurs in the centrosome and may help organize a mitotic spindle for chromosome movement during animal cell division. |
| cilia (sing., cilium) | Short, hairlike projections from the plasma membrane, occurring usually in larger numbers. |
| flagellum (pl., flagella) | Long, slender extension used for locomotion by some bacteria, protozoans, and sperm. |
Created by:
Haleyannestes
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