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Definition
| Having both hydrophobic and hydrophilic regions, as in a phospholipid or a detergent molecule |
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| Pigmented protein found in abundance in the plasma membrane of the salt-loving archeon Halobacterium halobium; pumps protons out of the cell in response to light |
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| Short, rigid lipid molecule present in large amounts in the plasma membranes of animal cells, where it makes the lipid bilayer less flexible |
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| Soapy substance used to solubilize membrane proteins |
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| Protective layer of carbohydrates on the outside surface of the plasma membrane formed by the sugar residues of membrane glycoproteins, proteoglycans, and glycolipids |
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| Thin pair of closely juxtaposed sheets, composed mainly of phospholipid molecules, that forms the structural basis for all cell membranes. |
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| Functionally and structurally specialized region in the membrane of a cell or organelle; typically characterized by the presence of specific proteins |
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| A protein associated with the lipid bilayer of a cell membrane |
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| Common phospholipid present in abundance in most cell membranes; uses choline attached to a phosphate as its head group |
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| The protein-containing lipid bilayer that surrounds a living cell |
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| Describes an organic molecule that contains a full complement of hydrogen; no double or triple C-C bonds |
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| Describes an organic molecule that contains one or more double or triple C-C bond |
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| Traveling wave of electrical excitation caused by rapid, transient, self-propagating depolarization of the plasma membrane in a neuron or other excitable cell; also called a nerve impulse |
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| The movement of a solute across a membrane against its electrochemical gradient; requires an input of energy, such as that provided by ATP hydrolysis |
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| Type of coupled transporter that transfers two different ions or small molecules across a membrane in opposite directions, either simultaneously or in sequence |
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| Long, thin extension that conducts electrical signals away from a nerve cell body toward remote target cells |
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| An active transporter that uses energy supplied by ATP hydrolysis to actively EXPEL Ca2+ from the cell cytosol |
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| A protein that forms a hydrophilic pore across a membrane, through which selected small molecules or ions can passively diffuse |
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| Active transporter that uses the movement of one solute down its electrochemical gradient to drive the uphill transport of another solute across the same membrane |
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| Short, branching structure that extends from the surface of a nerve cell and receives signals from other neurons |
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| A shift in the membrane potential, making it less negative |
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| Driving force that determines which way an ion will move across a membrane; consists of the combined influence of the ion's concentration gradient and the membrane potential |
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| Transporters that pump H+ out of the cell, thus setting up an electrochemical proton gradient across the membrane and creating an acid pH in the medium surrounding the cell |
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| Transmembrane protein that forms a pore across the lipid bilayer through which specific inorganic ions can diffuse down their electrochemical gradient |
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| Ion channel permeable to K+ that randomly flickers between an open and closed state; largely responsible for the resting membrane potential in animal cells |
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| An ion channel that is stimulated to open by the binding of a small molecule such as a neurotransmitter |
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| Mechanically-gated channels |
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Definition
| An ion channel that allows passage of a select ions across a membrane in response to a physical perturbation |
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Definition
| Voltage difference across amembrane due to a slight excess of positive ions on one side and of negative ions on the other |
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| Membrane transport protein |
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Definition
| Any transmembrane protein that provides a passageway for the movement of select substances across a cell membrane |
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| Transporter found in the plasma membrane of most animal ells that actively pumps Na+ out of the cell and K+ in, using energy from ATP hydrolysis |
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| An equation that relates the concentrations of an inorganic ion on the two sides of a permeable membrane to the membrane potential at which there would be no net movement of the ion across the membrane |
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| Structure at the end of an axon that signals to another neuron or target cell |
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| An electrically excitable cell that integrates and transmits information as part of the nervous system |
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| Small signaling molecule secreted by a nerve cell at a synapse to transmit information to a post synaptic cell. Examples include acetylcholine, glutamate, GABA, and glycine. |
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| Technique that uses light to control the activity of neurons into which light-gated ion channels have been artificially introduced |
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| Passive movement of water across a cell membrane from a region where the [water] is high to a region where [water] is low (region of low [solute] to region of high [solute]) |
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| Spontaneous movement of a solute down its concentration gradient across a cell membrane via a membrane transport protein, such as a channel or a transporter |
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| Technique used to monitor the activity of ion channels in a membrane; involves the formation of a tight seal between the tip of a glass electrode and a small region of cell membrane, and manipulation of the membrane potential by varying the concentrations of ions in the electrode |
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| Transporter that uses energy to move a solute actively against its electrochemical gradient |
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| resting membrane potential |
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Definition
| Voltage difference across the plasma membrane when a cell is not stimulated |
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| A transporter that transfers two different solutes across a cell membrane in the same direction |
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| Specialized junction where a nerve cell communicates with another cell (such as a nerve cell, muscle cell, or gland cell), usually via a neurotransmitter secreted by the nerve cell |
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| The ability of a synapse to adjust its strength for a prolonged period, either up or down, usually via a neurotransmitter secreted by the nerve cell |
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| Small membrane-enclosed sac filled with neurotransmitter that releases its contents by exocytosis at a synapse |
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Term
| transmitter-gated ion channel |
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Definition
| Transmembrane receptor protein or protein complex that opens in response to the binding of a neurotransmitter, allowing the passage of a specific inorganic ion; its activation can trigger an action potential in a postsynaptic cell |
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| Channel protein that permits the passage of selected ions, such as Na+, across a membrane in response to changes in the membrane potential. Found primarily in electrically excitable cells such as nerve and muscle. |
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| voltage-gated Na+ channel |
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Definition
| Protein in the plasma membrane of electrically excitable cells that opens in response to membrane depolarization, allowing Na+ to enter the cell. It is responsible for action potentials in these cells |
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| In chloroplasts and photosynthetic bacteria, the part of the membrane-bound photosystem that captures energy from sunlight; contains an array of proteins that bind hundreds of chlorophyll molecules and other photosensitive pigments |
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| Membrane-associated enzyme complex that catalyzes the formation of ATP from ADP and inorganic phosphate during oxidative phosphorylation and photosynthesis |
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| Process by which green plants and other photosynthetic organisms incorporate carbon atoms from atmospheric carbon dioxide into sugars. The second stage of photosynthesis. |
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| Mechanism that uses the energy stored in a transmembrane proton gradient to drive an energy-requiring process, such as the synthesis of ATP or the transport of a molecule across a membrane |
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| Light-absorbing green pigment that plays a central part in photosynthesis |
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| Specialized organelle in algae and plants that contains chlorophyll and serves as the site in which photosynthesis takes place |
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| Membrane bound, colored, heme-containing protein that transfers electrons during cellular respiration and photosynthesis |
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| Protein complex that serves as the final electron carrier in the respiratory chain; removes electrons from cytochrome c and passes them to O2 to produce H2O. |
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| Set of reactions in photosynthesis that produce sugars from CO2; AKA carbon fixation; can occur in absence of light |
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| A series of membrane-embedded electron carrier molecules that facilitate the movement of electrons from a higher to a lower energy level. as in oxidative phosphorylation and photosynthesis |
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| Metal complex found in electron carriers that operate early in the electron-transport chain; has a relatively weak affinity for electrons |
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| In photosynthesis, the set of reactions that converts the energy of sunlight into chemical energy in the form of ATP and NADH |
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| Large internal compartment within a mitochondrion |
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| Membrane-enclosed organelle about the size of a bacterium that carries out oxidative phosphorylation and produces most ATP in cells |
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| Conversion of nitrogen gas from the atmosphere into nitrogen-containing molecules by soil bacteria and cyanobacteria |
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| oxidative phosphorylation |
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Definition
| Process in bacteria and mitochondria in which ATP formation is driven by the transfer of electrons from food molecules to molecular oxygen |
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| The process by which plants, algae, and some bacteria use the energy of sunlight to drive the synthesis of organic molecules from carbon dioxide and water |
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| Large multiprotein complex containing chlorophyll that captures light energy and converts it into chemical energy; consists of a set of antenna complexes and a reaction center |
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| Small, lipid-soluble mobile electron carrier molecule found in the respiratory and photosynthetic electron transport chains |
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| In photosynthetic membranes, a protein complex that contains a specialized pair of chlorophyll molecules that performs photochemical reactions to convert the energy of photons (light) into high-energy electrons for transport down the photosynthetic electron transport chain. |
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| Two molecules that can be interconverted by the gain or loss of an electron; ex. NADH and NAD+ |
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| A measure of the tendency of a given redox pair to donate or accept electrons |
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| A reaction in which electrons are transferred from one chemical species to another. An oxidation-reduction reaction |
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| respiratory enzyme complex |
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Definition
| Set of proteins in the inner mitochondrial membrane that facilitates the transfer of high-energy electrons from NADH to water while pumping protons into the intermembrane space |
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| In a chloroplast, the large interior space that contains the enzymes needed to incorporate CO2 into sugars during the carbon-fixation stage of photosynthesis; equivalent to the matrix of a mitochondrion |
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| In a chloroplast, the flattened disc-like sac whose membranes contain the proteins and pigments that convert light energy into chemical energy during photosynthesis |
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| Mechanism by which a cell "eats itself," digesting molecules and organelles that are damaged or obsolete |
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| Molecule that steers proteins along productive folding pathways, helping them to fold correctly and preventing them from forming aggregates inside the cell |
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| Protein that makes up the coat of a type of transport vesicle that buds from either the Golgi apparatus (on the outside secretory pathway) or from the plasma membrane (on the inward endocytic pathway) |
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| Small membrane-enclosed sac that wears a distinctive layer of proteins on its cytosolic surface. It is formed by pinching-off of a protein-coated region of cell membrane |
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| Process by which cells take in materials through invagination of the plasma membrane, which surrounds the ingested material in a membrane-enclosed vesicle |
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| Interconnected network of membrane-enclosed organelles in a eukaryotic cell, including the ER, golgi, lysosomes, peroxisomes and endosomes |
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| Labyrinthine membrane-enclosed compartment in the cytoplasm of eukaryotic cells where lipids and proteins are made |
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| Membrane-enclosed compartment of a eukaryotic cell through which material ingested by endocytosis passes on its way to lysosomes |
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| Process by which most molecules are secreted from a eukaryotic cell. These molecules are packaged in membrane-enclosed vesicles that fuse with the plasma membrane, releasing their contents outside. |
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| Membrane-enclosed organelle in eukaryotic cells that modifies the proteins and lipids made in the ER and sorts them for transport to other sites |
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| Membrane-enclosed organelle that breaks down worn out proteins and organelles and other waste materials, as well as endocytosis-engulfed molecules; contains digestive enzymes that are most active at the pH found inside the organelle. |
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| Membrane-enclosed organelle |
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Definition
| Any organelle in the eukaryotic cell surrounded by a lipid bilayer; ex. ER, golgi, lysosome |
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| Double membrane surrounding the nucleus. Consists of outer and inner membranes, perforated by nuclear pores |
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| Channel through which selected large molecules move between the nucleus and the cytoplasm |
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| Small membrane-enclosed organelle that contains enzymes that degrade lipids and destroy toxins |
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| A cell such as a macrophage or neutrophil that is specialized to take up particles and microorganisms by phagocytosis. |
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| Process of endocytosis by which material is engulfed by a cell |
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| Process of endocytosis in which soluble materials are taken up from the environment and incorporated into vesicles to be digested |
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| A family of small GTP-binding proteins present on the surfaces of transport vesicles and organelles that serves as a molecular marker to help ensure that transport vesicles fuse only with the correct membrane |
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| receptor-mediated endocytosis |
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Definition
| Mechanism of selective uptake of material by animal cells in which a macromolecule binds to a receptor in the plasma membrane and enters the cell in a clathrin-coated vesicle |
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| Region of the ER associated with ribosomes and involved in the synthesis of secreted and membrane-bound proteins |
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| Production and release of a substance from a cell |
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| Membrane enclosed organelles in which molecules destined for secretion are stored prior to release. Sometimes called a secretory granule because darkly staining contents make the organelle visible as a small solid object |
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| Amino acid sequence that directs a protein to a specific location in the cell, such as the nucleus or mitochondria |
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| One of a family of membrane proteins responsible for the selective fusion of vesicles with a target membrane inside of the cell |
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| Membrane vesicle that carries protein from one intracellular compartment to another, ex. ER to golgi |
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| Unfolded protein response (UPR) |
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Definition
| Molecular program triggered by the accumulation of misfolded proteins in the ER. Allows cells to expand the ER and produce more of the molecular machinery needed to restore proper protein folding and processing. |
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| Movement of material between organelles in the eukaryotic cell via membrane-enclosed vesicles |
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