| Question | Answer |
| light microscope | An optical instrument with lenses that refract (bend) visible light to magnify images of specimens. |
| organelle | Any of several membrane-enclosed structures with specialized functions, suspended in the cytosol of eukaryotic cells. |
| electron microscope | A microscope that uses magnets to focus an electron beam on or through a specimen, resulting in resolving power a thousandfold greater than that of a light microscope |
| cell fractionation | The disruption of a cell and separation of its parts by centrifugation. |
| cytosol | The contents of the cell, exclusive of the nucleus and bounded by the plasma membrane. |
| eukaryotic cell | A type of cell with a membrane-enclosed nucleus and membrane-enclosed organelles. Organisms with eukaryotic cells (protists, plants, fungi, and animals) are called eukaryotes. |
| prokaryotic cell | A type of cell lacking a membrane-enclosed nucleus and membrane-enclosed organelles. Organisms with prokaryotic cells (bacteria and archaea) are called prokaryotes. |
| nucleus | (1) An atom’s central core, containing protons and neutrons. (2) The chromosome-containing organelle of a eukaryotic cell. (3) A cluster of neurons. |
| nuclear envelope | The double membrane in a eukaryotic cell that encloses the nucleus, separating it from the cytoplasm. |
| nuclear lamina | A netlike array of protein filaments lining the inner surface of the nuclear envelope; it helps maintain the shape of the nucleus. |
| chromosome | A cellular structure carrying genetic material, found in the nucleus of eukaryotic cells. |
| nucleolus | A specialized structure in the nucleus, consisting of chromatin regions containing ribosomal RNA genes along with ribosomal proteins imported from the cytoplasmic site of rRNA synthesis and ribosomal subunit assembly. |
| vesicle | A sac made of membrane in the cytoplasm. |
| endoplasmic reticulum | An extensive membranous network in eukaryotic cells, continuous with the outer nuclear membrane and composed of ribosome-studded (rough) and ribosome-free (smooth regions. |
| smooth ER | That portion of the endoplasmic reticulum that is free of ribosomes. |
| rough ER | That portion of the endoplasmic reticulum studded with ribosomes. |
| glycoprotein | A protein with one or more carbohydrates covalently attached to it. |
| Golgi apparatus | An organelle in eukaryotic cells consisting of stacks of flat membranous sacs that modify, store, and route products of the endoplasmic reticulum and synthesize some products, notable non-cellulose carbohydrates. |
| phagocytosis | A type of endocytosis in which large particulate substances are taken up by a cell. It is carried out by some protists and by certain immune cells of animals (in mammals, mainly macrophages, neutrophils, and dendritic cells). |
| contractile vacuole | A membranous sac that helps move excess water out of certain fresh-water protists. |
| mitochondrion | An organelle in eukaryotic cells that serves as the site of cellular respiration. |
| peroxisome | An organelle containing enzymes that transfer hydrogen (H2) from various substrates to (O2), producing and then degrading hydrogen peroxide (H2O2). |
| thylakoid | A flattened membranous sac inside a chloroplast. Thylakoids exist in an interconnected system in the chloroplast and contain the molecular “machinery” used to convert light energy to chemical energy. |
| granum | A stack of membrane-bounded thylakoids in the chloroplast. Grana function in the light reactions of photosynthesis. |
| cytoskeleton | A network of microtubules, microfilaments, and intermediate filaments that branch throughout the cytoplasm and serve a variety of mechanical, transport, and signaling functions. |
| centrosome | Structure present in the cytoplasm of animal cells, important during cell division; functions as a microtubule-organizing center. A centrosome has two centrioles. |
| flagellum | A long cellular appendage specialized for locomotion |
| cilium | A short cellular appendage containing microtubules |
| microfilament | A cable composed of actin proteins in the cytoplasm of almost every eukaryotic cell, making up almost every eukaryotic cell, making up part of the cytoskeleton and action alone or with myosin to cause cell contraction; also known as an actin filament. |
| cortex | The outer region of cytoplasm in a eukaryotic cell, lying just under the plasma membrane, that has a more gel-like consistency than the inner regions, due to the presence of multiple microfilaments. |
| myosin | A type of protein filament that acts as a motor protein with actin filaments to cause cell contraction. |
| cytoplasmic streaming | A circular flow of cytoplasm, involving myosin and actin filaments, that speeds the distribution of materials within cells. |
| intermediate filament | A component of the cytoskeleton that includes filaments intermediate in size between microtubules and microfilaments. |
| cell wall | A protective layer external to the plasma membrane in the cells of plants, prokaryotes, fungi, and some protists. |
| primary cell wall | In plants, a relatively thin and flexible layer first secreted by a young cell. |
| secondary cell wall | In plants, a strong and durable matrix often deposited in several laminated layers for cell protection and support. |
| extracellular matrix | The substance in which animal cells are embedded, consisting of protein and polysaccharides synthesized and secreted by cells. |
| fibronectin | A glycoprotein that helps animal cells attach to the extracellular matrix. |
| plasmodesma | An open channel in the cell wall of a plant through which strands of cytosol connect from an adjacent cell. |
