Term | Definition |
cytology | the branch of biology concerned with the structure and function of plant and animal cells. |
cell | the smallest structural and functional unit of an organism, typically microscopic and consisting of cytoplasm and a nucleus enclosed in a membrane. Microscopic organisms typically consist of a single cell, which is either eukaryotic or prokaryotic. |
organelle | any of a number of organized or specialized structures within a living cell. |
organism | an individual animal, plant, or single-celled life form. |
unicellular | consisting of a single cell. |
multicellular | having or consisting of many cells. |
prokaryotic | a microscopic single-celled organism that has neither a distinct nucleus with a membrane nor other specialized organelles. Prokaryotes include the bacteria and cyanobacteria. |
eukaryotic | An organism whose cells contain a nucleus surrounded by a membrane and whose DNA is bound together by proteins (histones) into chromosomes. |
eukaryotes | an organism consisting of a cell or cells in which the genetic material is DNA in the form of chromosomes contained within a distinct nucleus. Eukaryotes include all living organisms other than the eubacteria and archaebacteria. |
cell theory | that includes one or both of the statements that the cell is the fundamental structural and functional unit of living matter and that the organism is composed of autonomous cells with its properties being the sum of those of its cells. |
virus | an infective agent that typically consists of a nucleic acid molecule in a protein coat, is too small to be seen by light microscopy, and is able to multiply only within the living cells of a host. |
tissues | any of the distinct types of material of which animals or plants are made, consisting of specialized cells and their products. |
organs | a part of an organism that is typically self-contained and has a specific vital function, such as the heart or liver in humans. |
diffusion/passive transport | a movement of ions and other atomic or molecular substances across cell membranes without need of energy input. active transport does not require an input of cellular energy because it is instead driven by the tendency of the system to grow in entropy. |
osmosis | a process by which molecules of a solvent tend to pass through a semipermeable membrane from a less concentrated solution into a more concentrated one, thus equalizing the concentrations on each side of the membrane. |
active transport | the movement of ions or molecules across a cell membrane into a region of higher concentration, assisted by enzymes and requiring energy. |
semi-permeable | allowing certain substances to pass through it but not others, especially allowing the passage of a solvent but not of certain solutes. |
phagocytosis | is the process by which a cell—often a phagocyte or a protist—engulfs a solid particle to form an internal compartment |
pinocytosis | the ingestion of liquid into a cell by the budding of small vesicles from the cell membrane. |