| A | B |
|---|
| organization | the orderly structure of cells in an organism |
| cell | basic unit of structure and organization of all living organisms |
| cell theory | is one of the fundamental ideas of modern biology and includes three principles |
| plasma membrane | a special boundary that helps control what enters and leaves the cell |
| organelle | specialized structures that carry out specific cell functions |
| eukaryotic cell | contains a nucleus and other organelles that are bound by membranes |
| nucleus | a distinct central organelle that contains the cell's genetic material in the form of DNA |
| prokaryotic cell | cells without a nucleus or other membrane-bound organelles |
| ion | atom that is negatively or positively charged because it has lost or gained one or more electrons |
| selective permeability | a large property ofthe plasma membrane by which a memrane allows some substances to pass through while keeping others out. |
| phospholipid bilayer | two layers are arranged tail-to-tail |
| transport protein | move needed substances or waste materials through the plasma membrane and contribute to the selective permeability of the plasma membrane |
| fluid mosaic model | a plasma membrane with components constantly in motion, sliding past one another within the lipid bilayer |
| enzyme | protein that speeds up a biological reaction by lowering the activation energy needed to start the reaction |
| cytoplasm | a semifluid material inside the plasma membrane |
| cytoskeleton | a supporting networkof long, thin protein fibers that form a frameword for the cell and provide an anchor for the organelles inside the cell |
| ribosome | the organelles that help manufacture proteins |
| nucleolus | the site of ribosome production within the nucleus |
| endoplasmic reticulum | a membrane system of folded sacs and interconnected channels that serves as the site for protein and lipid synthesis |
| Golgi apparatus | a flattened stack ofmembranes that modifies, sorts, and packages proteins into sacs called vesicles |
| vacuole | a sac used to store food, enzymes, and other materials needed by a cell |
| lysosome | vesicles that contain substances that digest excess or worn-out organelles and food particles |
| centriole | organelles made of microtubules that function during cell division |
| mitochondrion | energy generators that convert fuel particles into usable energy |
| chloroplast | organelles that capture light energy and convert it to chemical energy |
| cell wall | a thick, rigid, mesh of fibers that surrounds the outside of the plasma membrane, protecting the cell and giving it support |
| cilium | short, hairlike projection that functions in cell movement |
| flagellum | long, tail-like projection with a whiplike motion that helps a cellmove through a watery environment |
| homeostasis | regulation of an organism's internal environment to maintain conditions needed for life |
| diffusion | net movement of particles from an area where there are many particles of the substance to an area where there are fewer particles of the substance |
| dynamic equilibrium | a condition in which there is continuous movement but no overall change |
| facilitated diffusion | uses transport proteins to move other ions and small molecules across the plasma membrane |
| osmosis | the diffusion of water across a selectively permeable membrane |
| isotonic solution | a solution with the same concentration of water and solutes as inside a cell, resulting in the cell retaining its normal shape because there is no net movement of water |
| hypotonic solution | has a lower concentration of solute outside than inside the cell, causing water to flow into the cell by osmosis |
| hypertonic solution | has a higher concentration of solute outside than inside a cell, causing water to leave the cell by osmosis |
| active transport | movement of substances across the plasma membrane against a concentration gradient requires energy |
| endocytosis | energy-requiring process by which large substances from the outside environment can enter a cell |
| extocytosis | energy-requiring process by which a cell expels wastes and secretes substances at the plasma membrane |
