Chapter 1 : Cell Biology The study of cells, their structures, and their functions. Cell Theory All living organisms are composed of one or more cells; cells are the smallest living things and basic units of organization; cells arise only from previously existing cells. Fundamental Unit of Life The cell. Plasma Membrane A structure found in all cells that surrounds the cell. Cytoplasm The area of the cell that includes the cytosol. Cytosol The fluid portion of the cell outside the organelles. Genetic Material The DNA contained within cells. Prokaryote An organism whose cells do not have a true nucleus. Eukaryote An organism whose cells have a true nucleus. Prokaryotes Bacteria and Archaea. Eukaryotes Animals, plants, fungi, and protists. Prokaryotic Cell Usually a single cell with no true nucleus and typically one circular chromosome. Eukaryotic Cell A cell with a true nucleus and membrane-bound organelles. True Nucleus A nucleus that contains DNA and is enclosed by a nuclear envelope. Virus A non-cellular entity that requires cells to survive and reproduce. Obligate Intracellular Parasite An organism or entity that requires a cell to survive and reproduce; viruses are sometimes called this. Light Microscope A microscope that can be used to view live or dead cells and can show structures such as the membrane, nucleus, cytoplasm, and larger organelles. Electron Microscope A microscope with much higher resolution than a light microscope; specimens must be fixed (dead). TEM Transmission Electron Microscopy; used to examine thin sections of tissues and internal structures. SEM Scanning Electron Microscopy; used to examine surfaces of cells or tissues. Fluorescence Microscopy Microscopy that uses fluorescent labels to see specific tagged cell structures. Cell Resolution The human eye resolves about 200 µm, while typical cells are about 5–20 µm. Nucleus Contains DNA and is involved in DNA replication. Mitochondria Organelles that make ATP through aerobic cellular respiration. ATP The energy-containing molecule produced by mitochondria. Aerobic Cellular Respiration The process carried out by mitochondria to make ATP. Chloroplast An organelle involved in photosynthesis and found in plant cells. Photosynthesis The process in which light energy and CO2 are used to produce food. Rough ER The organelle involved in making proteins; it has ribosomes attached to it. Ribosomes Structures associated with the rough ER that are involved in protein production. Smooth ER An organelle involved in making lipids, storage, and modifying carbohydrates. Golgi Apparatus Modifies and sorts proteins and helps transport them. Vesicle A membrane-bound structure involved in transporting materials between organelles and to the plasma membrane. Exocytosis The process involving vesicles releasing materials through the plasma membrane. Cytoskeleton A system of filaments important for cell organization, structure, and movement. Actin Filaments Cytoskeletal structures involved in muscle contraction, cell crawling, cell shape, and pseudopodial cell extension. Microtubules Cytoskeletal structures involved in vesicle transport, chromosome movement, cilia, flagella, and the mitotic spindle. Intermediate Filaments Cytoskeletal structures important for stability and structural support. Mitotic Spindle A structure made of microtubules that helps move chromosomes during cell division. Cell Wall A structure found in plant cells and many prokaryotes that provides support. Vacuole A structure found in plant cells; plant cells have vacuoles in addition to their other organelles. Endosymbiosis The engulfment of bacteria by a larger cell. Endosymbiont Theory The theory that mitochondria and chloroplasts evolved from bacteria that were engulfed by ancestral cells. Mitochondrial Origin According to endosymbiont theory, mitochondria arose from an aerobic bacterium taken up by an anaerobic bacteria-like ancestor of eukaryotic cells. Chloroplast Origin According to endosymbiont theory, chloroplasts arose from photosynthetic bacteria taken up by an aerobic eukaryotic ancestor of plants. Evidence for Endosymbiont Theory Mitochondria and chloroplasts are bacteria-sized, have two membranes, have bacterial-like ribosomes, contain their own DNA, and divide similarly to bacteria. Mitochondrial DNA Mitochondria contain their own DNA, including a single circular chromosome similar to bacteria. Chloroplast DNA Chloroplasts contain their own DNA, including a single circular chromosome similar to bacteria. Double Membrane Mitochondria and chloroplasts have two membranes, supporting the endosymbiont theory. Common Ancestor Hypothesis The hypothesis that organisms descended from an ancestral prokaryote called LUCA or LUA. LUCA The Last Universal Common Ancestor; an ancestral prokaryote in the common ancestor hypothesis. Genome The genetic material of an organism, containing protein-coding genes and regulatory regions.y
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