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| study of the various types of energy transformations that occur in living organisms |
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| the capacity to do work, that is to change or move something |
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| study of the changes in energy that accompany events in the universe |
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| 1st law of thermodynamics |
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| law of conservation of energy; energy can be neither created nor destroyed, but can only be converted from one form to another |
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| the act of energy changing forms |
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| 2nd law of thermodynamics |
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| events in the universe tend to proceed "downhill" from a state of higher energy to a state of lower energy; there is decreasing free energy to do work |
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| events that are thermodynamically favorable and can occur without the input of external energy |
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| measure of disorder and chaos; associated with the random movements |
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| processes that are thermodynamically favorable; spontaneous |
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| processes that are thermodynamically unfavorable; not spontaneous |
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| equilibrium constant (Keq) |
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| ratio of the concentration of products to the concentration of reactants |
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| standard-free energy change |
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| (delta G degree prime) the free energy released when reactants are converted to produces under standard conditions |
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| the concentrations of reactants and produces remain relatively constant |
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| mediators of metabolism, responsible for virtually every reaction in a cell |
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| parts of the enzymes that are not proteins; can be inorganic or organic (coenzymes) |
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| reactants bound by an enzyme |
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| the sufficient kinetic energy required by reactants to overcome a barrier |
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| when reactants are at the crest of the energy hump and ready to be converted to products |
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| enzyme-substrate (ES) complex |
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| the complex an enzyme makes with its substrate to help it make and break bonds |
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| the part of the enzyme that is directly involved in binding the substrate |
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| conformation shifts so that the complementary fit between the enzyme and reactants is improved |
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| maximum number of molecules of substrate that can be converted to product by one enzyme molecule per unit time |
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| the substrate concentration when the reaction velocity is one-half of the maximum velocity |
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| molecules that are able to bind to an enzyme and decrease its activity |
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| bind very tightly to an enzyme, often with a covalent bond to one of the amino acid residues |
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| reversible inhibitors that compete with a substrate for access to the active site of an enzyme |
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| noncompetitive inhibition |
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Definition
| substrate and inhibitor do not compete for the same binding site; the inhibitor acts at a site other than the enzyme's active site |
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| collection of biochemical reactions that occur within a cell; tremendous diversity of molecular conversions |
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| sequence of chemical reactions in which each reaction is catalyzed by a specific enzyme, and the product of one reaction is the substrate for the next |
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| compounds formed in each step of a metabolic pathway that lead ultimately to the formation of an end product |
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| compounds formed in each step of a metabolic pathway that lead ultimately to the formation of an end product |
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| where disassembley of complex molecules to form simpler products occurs; make raw materials available and energy to build other molecules or perform tasks |
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| where the synthesis of more complex compounds from simpler starting materials occurs; use energy |
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| oxidation-reduction (redox) reaction |
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Definition
| reaction that involves a change in the electronic state of the reactants (electrons are transferred from one reactant to another) |
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loss of electrons --> oxidation
gain of electrons --> reduction |
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| the sunstance that is oxidized |
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| the substance that is reduced |
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| occurs in the cytosol, leads to formation of pyruvate; 1st step in glucose metabolism |
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| tricarboxylic aicd (TCA) cycle |
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| 2nd step in glucose metabolism; occurs in mitochondria leads to the final oxidation of the carbon atoms to carbon dioxide |
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| enzyme that catalyzes a reaction that involves the transfer of a hydride ion |
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| substrate-level phosphorylation |
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| occurs by transfer of a phosphate group from one of the stubstrates to ADP |
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| measure of the ability of a molecule to transfer any group to another molecule |
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| can proceed in the absence of molecular oxygen |
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| anaerobic 2nd step of glucose metabolism; occurs in cytosol; used when O2 is low to continue ATP production |
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| important measure of the cell's usable energy content, related to resevoir of NADPH |
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| enzymes that transfer phosphate groups to other proteins; regulate such diverse activities as hormone action, cell division, and gene expression |
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| mechanism whereby the activity of an enzyme is either inhibited or stimulated by a compound that binds to an allosteric site on the enzyme |
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| site that is spatially distinct from the enzyme's active site |
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| type of allosteric modulation in which the enzyme catalyzing the first committed step in a metabolic pathway is temporarily inactivated when the concentration of the end product of that pathway reaches a certain level |
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| anabolic pathway leading to the synthesis of glucose |
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| separates cell from environment, 5-10nm, thin, fragile; functions: scaffold for biochemical activities, selectively permeable membrane, compartmentalization, intercellular communication |
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| response of cell to external stimuli |
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| combine with specific molecules having a complementary structure |
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| specific molecules that bind with receptors |
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| membranes as dynamic structures in which both lipids and associated proteins are mobile and capable of moving within the membrane to engage in interactions with other membrane molecules |
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| contain both hydrophilic and hydrophobic regions |
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| lipids that contain a phosphate group; majority of membrane lipids |
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| lipid built on a glycerol backbone with a phosphate group; majority of membrane phospholipids |
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| highly water-soluble domain at one end of a membrane phospholipid |
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| membrane lipid;sphingosine linked to a fatty acid by its amino group |
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| sphingosine-based lipid molecules linked to carbohydrates, often active components of plasma membrane |
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| sterol found in animal cells that can constitute up to 50% of the lipid in the plasma membrane; realtive conc. effects the membrane fluidity |
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| phospholipid molecules assemble spontaneous to form the walls of fluid-filled spherical vesicles |
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| addition of a carbohydrate |
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| branched hydrophilic saccharides typically having having fewer than about 15 sugars per chain |
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| penetrate the lipid bilayer |
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| pass entirely through the lipid bilayer and have domains that protrude from both the extracellualr and cytoplasmic sides of the membrane |
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| located entirely outside of the lipid bilayer on either cytoplasmic or extracellular side |
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| located outside the lipid bilayer, on either extracellular or cytoplasmic side, but are covalently linked to a lipid molecule that is situated with in the bilayer |
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| freeze-fracture replication |
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Definition
| tissue is frozen solid and then struck with a knife blade, which fractures it into two; facture plane often takes a path between the two leaflets of the lipid bilayer; once the membranes are spolit, metals deposited on their exposed surface to form a shadowed replica, which is viewed in the electron microscope; |
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| segments of a protein embedded within the membrane; have a simple structure; consist of about 20 nonpolar amino acids in an alpha helix |
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| peripheral membrane proteins that are anchored via linkage to a glycosylphophatidylionsitol molecule of the bilayer |
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| where the fluidity of the membrane changes from liquid to gel |
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| microdomains within a cellular membrane that possess decreased fluidity due to the presence of cholesterol, glycolipids, and phospholipids contain longer, saturated fatty acids |
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| technique whereby two different types of cells or cells from two species, can be fused to produce one cell with a common cytoplasm and a single membrane |
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| spontaneous process in which a substance moves from a region of high concentration to a region of low concentration |
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| concentration difference of the substances and electric difference of the charged particles |
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| the ratio of its solubility in a nonpolar solvent to that in water under polar condiations |
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| fluorescence recovery after photobleaching (FRAP) |
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Definition
| cells are first labeled by link to a fluorescent dye then irradiated by a sharply focused laser which bleach the fluorescent molecules in its path; random movements of molecules in to bleached area gives rate of diffusion |
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| single-particle tracking (SPT) |
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Definition
| individual membrane proteins are labeled, movement of molecules are followed by computer enhanced video microscopy |
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| spontaneous process in which a substance moves from a region of high concentration to a region of low concentration |
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| a chemical gradient (concentration of substances) and an electronic gradient (difference in charge) |
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| membrane property of being freely permeable to water while allowing much slower passage to small ions and polar solutes |
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| water moving from a region of lower solute conc. to a region of higher solute conc. |
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| higher concentration of solute comparitively |
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| lower solute concentration comparatively |
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| equal solute concentration comparitively |
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| when plant cell placed into a hypertonic medium and the volume shrinks |
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| openings in the membrane that are permeable to specific ions; made from integral proteins |
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| exist in open or closed form and respond to signals to switch forms |
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| depend on difference in ionic charge across the membrance (i.e. Na+ channels) |
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| depend on the binding of specific molecule (usually not solute) (i.e. neurotransmitters) |
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| depend on mechanical forces applied to membrane (i.e. stereocilia on the hair cells of ears) |
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| transmembrane protein that binds a specific substance and changes conformation so as to facilitate diffusion of the substance down its conc. gradient |
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| process by which the diffusion rate of a substance is increased through interaction with a substance-specific membrane protein |
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| energy-requiring process in which a substance binds to a specific transmembrane protein, changing its conformation to allow passage of the substance through the membrane against the electrochemical gradient |
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| process that couples the movement of two solutes across a membrane, termed symport if the two solutes are moved in the same direction and antiport if the two move in opposite directions |
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| fine extension from cell body in neuron, which receive incoming information from external sources |
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| single extension from cell body, which conducts outgoing impulses away from cell body toward target cells |
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| site where impulses are transmitted from neuron to target cell |
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| voltage caused by difference of charge particles across non excitable cells |
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| voltage caused by difference of charged particle in excitable cells (muscle and nerve) |
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| movement of voltage toward zero |
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| certain voltage point of nerve cell at which an AP is generated |
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| collective changes in membrane potential, beginning with depolarization to threshold and ending with return to resting potential, that occur with stimulation of an excitable cell and act as the basis for neural communication |
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| propagation of an AP down the length of the nerve |
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| nerve impulse jumps from node to node of Ranvier without activating the membrance inbetween (in myelinated cells) |
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| lipid-rich material wrapped around most neurons in the vertebrate body |
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| junctions between neurons and target cells |
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| gap between neuron and target cell (20 to 50 nm) |
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| neuron, muscle cell, or gland cell after synapse |
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| synapse between the terminal branches of an axon and a skeletal muscle cell |
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| storage sites for the chemical transmitters that act on postsynaptic cells |
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| chemical transmitters released to act on postsynaptic cell |
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