SC146 U2 Matching Topics 1 and 2

Term Definition
cell membrane an extremely pliable structure composed primarily of back-to-back phospholipids (a “bilayer”)
hydrophilic attracted to water
hydrophobic repels and is repelled by water
amphipathic contains both a hydrophilic and a hydrophobic region
intracellular fluid (ICF) the fluid interior of the cell
extracellular fluid (ECF) the fluid environment outside the enclosure of the cell membrane
Interstitial fluid (IF) the term given to extracellular fluid not contained within blood vessels
integral protein a protein that is embedded in the membrane
channel protein an example of an integral protein that selectively allows particular materials, such as certain ions, to pass into or out of the cell
receptor a type of recognition protein that can selectively bind a specific molecule outside the cell, and this binding induces a chemical reaction within the cell
ligand the specific molecule that binds to and activates a receptor
glycoprotein a protein that has carbohydrate molecules attached, which extend into the extracellular matrix
glycocalyx a fuzzy-appearing coating around the cell formed from glycoproteins and other carbohydrates attached to the cell membrane
peripheral proteins proteins that typically perform a specific function for the cell
selective permeability allows only substances meeting certain criteria to pass through the cell membrane unaided
passive transport the movement of substances across the membrane without the expenditure of cellular energy
active transport the movement of substances across the membrane using energy from adenosine triphosphate (ATP)
concentration gradient the difference in concentration of a substance across a space
diffusion the movement of particles from an area of higher concentration to an area of lower concentration
facilitated diffusion diffusion process used for those substances that cannot cross the lipid bilayer due to their size, charge, and/or polarity
osmosis the diffusion of water through a semipermeable membrane down its concentration gradient
hypotonic a solution that has a lower concentration of solutes than another solution
hypertonic a solution that has a higher concentration of solutes than another solution
isotonic two solutions that have the same concentration of solutes
symporters secondary active transporters that move two substances in the same direction
antiporters secondary active transport systems that transport substances in opposite directions
endocytosis the process of a cell ingesting material by enveloping it in a portion of its cell membrane, and then pinching off that portion of membrane
phagocytosis endocytosis of large particles (cell eating)
vesicle a spherical and hollow organelle bounded by a lipid bilayer membrane
pinocytosis process that brings fluid containing dissolved substances into a cell through membrane vesicles (cell drinking)
receptor-mediated endocytosis endocytosis by a portion of the cell membrane that contains many receptors that are specific for a certain substance
exocytosis process of a cell exporting material using vesicular transport (taking "out of the cell")
cytosol jelly-like substance within the cell, provides the fluid medium necessary for biochemical reactions
organelle one of several different types of membrane-enclosed bodies in the cell, each performing a unique function
cytoplasm composed of the organelles and cytosol
nucleus a cell’s central organelle, which contains the cell’s DNA
endoplasmic reticulum (ER) a system of channels that is continuous with the nuclear membrane (or “envelope”) covering the nucleus and composed of the same lipid bilayer material
ribosome an organelle that serves as the site of protein synthesis
golgi apparatus responsible for sorting, modifying, and shipping off the products that come from the rough ER
lysosome an organelle that contains enzymes that break down and digest unneeded cellular components, such as a damaged organelle
autophagy the process of a cell digesting its own structures (cell eating)
autolysis process of lysosomes being triggered to open up and release digestive enzymes into the cytoplasm of the cell, killing the cell
mitochondrion a membranous, bean-shaped organelle that is the “energy transformer” of the cell
peroxisomes membrane-bound organelles that contain an abundance of enzymes for detoxifying harmful substances and lipid metabolism
cytoskeleton a group of fibrous proteins that provide structural support for cells, critical for cell motility, reproduction, and transportation of substances within the cell
microtubule maintain cell shape and structure, help resist compression of the cell, and play a role in positioning the organelles within the cell
microfilament thinner cytoskeletal filament, actin is the primary component, responsible for muscle contraction (along with myosin)
intermediate filament made up of long fibrous subunits of a protein called keratin, important for maintaining cell shape and structure

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