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microscope : an instrument that magnifies an object
https://openstax.org/books/biology/pages/4-key-terms
microtubule : widest element of the cytoskeleton system; it helps the cell resist compression, provides a track along which vesicles move through the cell, pulls replicated chromosomes to opposite ends of a dividing cell, and is the structural element of centrioles, flagella, and cilia
https://openstax.org/books/biology/pages/4-key-terms
mitochondria : (singular = mitochondrion) cellular organelles responsible for carrying out cellular respiration, resulting in the production of ATP, the cell’s main energy-carrying molecule
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nuclear envelope : double-membrane structure that constitutes the outermost portion of the nucleus
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nucleoid : central part of a prokaryotic cell in which the chromosome is found
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nucleolus : darkly staining body within the nucleus that is responsible for assembling the subunits of the ribosomes
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nucleoplasm : semi-solid fluid inside the nucleus that contains the chromatin and nucleolus
https://openstax.org/books/biology/pages/4-key-terms
nucleus : cell organelle that houses the cell’s DNA and directs the synthesis of ribosomes and proteins
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organelle : compartment or sac within a cell
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peroxisome : small, round organelle that contains hydrogen peroxide, oxidizes fatty acids and amino acids, and detoxifies many poisons
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plasma membrane : phospholipid bilayer with embedded (integral) or attached (peripheral) proteins, and separates the internal content of the cell from its surrounding environment
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plasmodesma : (plural = plasmodesmata) channel that passes between the cell walls of adjacent plant cells, connects their cytoplasm, and allows materials to be transported from cell to cell
https://openstax.org/books/biology/pages/4-key-terms
prokaryote : unicellular organism that lacks a nucleus or any other membrane-bound organelle
https://openstax.org/books/biology/pages/4-key-terms
ribosome : cellular structure that carries out protein synthesis
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rough endoplasmic reticulum (RER) : region of the endoplasmic reticulum that is studded with ribosomes and engages in protein modification and phospholipid synthesis
https://openstax.org/books/biology/pages/4-key-terms
smooth endoplasmic reticulum (SER) : region of the endoplasmic reticulum that has few or no ribosomes on its cytoplasmic surface and synthesizes carbohydrates, lipids, and steroid hormones; detoxifies certain chemicals (like pesticides, preservatives, medications, and environmental pollutants), and stores calcium ions
https://openstax.org/books/biology/pages/4-key-terms
tight junction : firm seal between two adjacent animal cells created by protein adherence
https://openstax.org/books/biology/pages/4-key-terms
unified cell theory : a biological concept that states that all organisms are composed of one or more cells; the cell is the basic unit of life; and new cells arise from existing cells
https://openstax.org/books/biology/pages/4-key-terms
vacuole : membrane-bound sac, somewhat larger than a vesicle, which functions in cellular storage and transport
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vesicle : small, membrane-bound sac that functions in cellular storage and transport; its membrane is capable of fusing with the plasma membrane and the membranes of the endoplasmic reticulum and Golgi apparatus
https://openstax.org/books/biology/pages/4-key-terms
active transport : method of transporting material that requires energy
https://openstax.org/books/biology/pages/5-key-terms
amphiphilic : molecule possessing a polar or charged area and a nonpolar or uncharged area capable of interacting with both hydrophilic and hydrophobic environments
https://openstax.org/books/biology/pages/5-key-terms
antiporter : transporter that carries two ions or small molecules in different directions
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aquaporin : channel protein that allows water through the membrane at a very high rate
https://openstax.org/books/biology/pages/5-key-terms
carrier protein : membrane protein that moves a substance across the plasma membrane by changing its own shape
https://openstax.org/books/biology/pages/5-key-terms
caveolin : protein that coats the cytoplasmic side of the plasma membrane and participates in the process of liquid update by potocytosis
https://openstax.org/books/biology/pages/5-key-terms
channel protein : membrane protein that allows a substance to pass through its hollow core across the plasma membrane
https://openstax.org/books/biology/pages/5-key-terms
clathrin : protein that coats the inward-facing surface of the plasma membrane and assists in the formation of specialized structures, like coated pits, for phagocytosis
https://openstax.org/books/biology/pages/5-key-terms
concentration gradient : area of high concentration adjacent to an area of low concentration
https://openstax.org/books/biology/pages/5-key-terms
diffusion : passive process of transport of low-molecular weight material according to its concentration gradient
https://openstax.org/books/biology/pages/5-key-terms
electrochemical gradient : gradient produced by the combined forces of an electrical gradient and a chemical gradient
https://openstax.org/books/biology/pages/5-key-terms
electrogenic pump : pump that creates a charge imbalance
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endocytosis : type of active transport that moves substances, including fluids and particles, into a cell
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exocytosis : process of passing bulk material out of a cell
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facilitated transport : process by which material moves down a concentration gradient (from high to low concentration) using integral membrane proteins
https://openstax.org/books/biology/pages/5-key-terms
fluid mosaic model : describes the structure of the plasma membrane as a mosaic of components including phospholipids, cholesterol, proteins, glycoproteins, and glycolipids (sugar chains attached to proteins or lipids, respectively), resulting in a fluid character (fluidity)
https://openstax.org/books/biology/pages/5-key-terms
glycolipid : combination of carbohydrates and lipids
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glycoprotein : combination of carbohydrates and proteins
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hydrophilic : molecule with the ability to bond with water; “water-loving”
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hydrophobic : molecule that does not have the ability to bond with water; “water-hating”
https://openstax.org/books/biology/pages/5-key-terms
hypertonic : situation in which extracellular fluid has a higher osmolarity than the fluid inside the cell, resulting in water moving out of the cell
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hypotonic : situation in which extracellular fluid has a lower osmolarity than the fluid inside the cell, resulting in water moving into the cell
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integral protein : protein integrated into the membrane structure that interacts extensively with the hydrocarbon chains of membrane lipids and often spans the membrane; these proteins can be removed only by the disruption of the membrane by detergents
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isotonic : situation in which the extracellular fluid has the same osmolarity as the fluid inside the cell, resulting in no net movement of water into or out of the cell
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osmolarity : total amount of substances dissolved in a specific amount of solution
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osmosis : transport of water through a semipermeable membrane according to the concentration gradient of water across the membrane that results from the presence of solute that cannot pass through the membrane
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passive transport : method of transporting material through a membrane that does not require energy
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peripheral protein : protein found at the surface of a plasma membrane either on its exterior or interior side; these proteins can be removed (washed off of the membrane) by a high-salt wash
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pinocytosis : a variation of endocytosis that imports macromolecules that the cell needs from the extracellular fluid
https://openstax.org/books/biology/pages/5-key-terms
plasmolysis : detaching of the cell membrane from the cell wall and constriction of the cell membrane when a plant cell is in a hypertonic solution
https://openstax.org/books/biology/pages/5-key-terms
potocytosis : variation of pinocytosis that uses a different coating protein (caveolin) on the cytoplasmic side of the plasma membrane
https://openstax.org/books/biology/pages/5-key-terms
primary active transport : active transport that moves ions or small molecules across a membrane and may create a difference in charge across that membrane
https://openstax.org/books/biology/pages/5-key-terms
pump : active transport mechanism that works against electrochemical gradients
https://openstax.org/books/biology/pages/5-key-terms
receptor-mediated endocytosis : variation of endocytosis that involves the use of specific binding proteins in the plasma membrane for specific molecules or particles, and clathrin-coated pits that become clathrin-coated vesicles
https://openstax.org/books/biology/pages/5-key-terms
secondary active transport : movement of material that is due to the electrochemical gradient established by primary active transport
https://openstax.org/books/biology/pages/5-key-terms
selectively permeable : characteristic of a membrane that allows some substances through but not others
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solute : substance dissolved in a liquid to form a solution
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symporter : transporter that carries two different ions or small molecules, both in the same direction
https://openstax.org/books/biology/pages/5-key-terms
tonicity : amount of solute in a solution
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transport protein : membrane protein that facilitates passage of a substance across a membrane by binding it
https://openstax.org/books/biology/pages/5-key-terms
transporter : specific carrier proteins or pumps that facilitate movement
https://openstax.org/books/biology/pages/5-key-terms
uniporter : transporter that carries one specific ion or molecule
https://openstax.org/books/biology/pages/5-key-terms
activation energy : energy necessary for reactions to occur
https://openstax.org/books/biology/pages/6-key-terms
active site : specific region of the enzyme to which the substrate binds
https://openstax.org/books/biology/pages/6-key-terms
allosteric inhibition : inhibition by a binding event at a site different from the active site, which induces a conformational change and reduces the affinity of the enzyme for its substrate
https://openstax.org/books/biology/pages/6-key-terms
anabolic : (also, anabolism) pathways that require an input of energy to synthesize complex molecules from simpler ones
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ATP : adenosine triphosphate, the cell’s energy currency
https://openstax.org/books/biology/pages/6-key-terms
bioenergetics : study of energy flowing through living systems
https://openstax.org/books/biology/pages/6-key-terms
catabolic : (also, catabolism) pathways in which complex molecules are broken down into simpler ones
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chemical energy : potential energy in chemical bonds that is released when those bonds are broken
https://openstax.org/books/biology/pages/6-key-terms
coenzyme : small organic molecule, such as a vitamin or its derivative, which is required to enhance the activity of an enzyme
https://openstax.org/books/biology/pages/6-key-terms
cofactor : inorganic ion, such as iron and magnesium ions, required for optimal regulation of enzyme activity
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competitive inhibition : type of inhibition in which the inhibitor competes with the substrate molecule by binding to the active site of the enzyme
https://openstax.org/books/biology/pages/6-key-terms
denature : process that changes the natural properties of a substance
https://openstax.org/books/biology/pages/6-key-terms
endergonic : describes chemical reactions that require energy input
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enthalpy : total energy of a system
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entropy (S) : measure of randomness or disorder within a system
https://openstax.org/books/biology/pages/6-key-terms
exergonic : describes chemical reactions that release free energy
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feedback inhibition : effect of a product of a reaction sequence to decrease its further production by inhibiting the activity of the first enzyme in the pathway that produces it
https://openstax.org/books/biology/pages/6-key-terms
free energy : Gibbs free energy is the usable energy, or energy that is available to do work.
https://openstax.org/books/biology/pages/6-key-terms
heat : energy energy transferred from one system to another that is not work (energy of the motion of molecules or particles)
https://openstax.org/books/biology/pages/6-key-terms
heat energy : total bond energy of reactants or products in a chemical reaction
https://openstax.org/books/biology/pages/6-key-terms
induced fit : dynamic fit between the enzyme and its substrate, in which both components modify their structures to allow for ideal binding
https://openstax.org/books/biology/pages/6-key-terms
kinetic energy : type of energy associated with objects or particles in motion
https://openstax.org/books/biology/pages/6-key-terms
metabolism : all the chemical reactions that take place inside cells, including anabolism and catabolism
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phosphoanhydride bond : bond that connects phosphates in an ATP molecule
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potential energy : type of energy that has the potential to do work; stored energy
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substrate : molecule on which the enzyme acts
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thermodynamics : study of energy and energy transfer involving physical matter
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transition state : high-energy, unstable state (an intermediate form between the substrate and the product) occurring during a chemical reaction
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acetyl CoA : combination of an acetyl group derived from pyruvic acid and coenzyme A, which is made from pantothenic acid (a B-group vitamin)
https://openstax.org/books/biology/pages/7-key-terms
aerobic respiration : process in which organisms convert energy in the presence of oxygen
https://openstax.org/books/biology/pages/7-key-terms
anaerobic : process that does not use oxygen
https://openstax.org/books/biology/pages/7-key-terms
anaerobic cellular respiration : process in which organisms convert energy for their use in the absence of oxygen
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ATP synthase : (also, F1F0 ATP synthase) membrane-embedded protein complex that adds a phosphate to ADP with energy from protons diffusing through it
https://openstax.org/books/biology/pages/7-key-terms
chemiosmosis : process in which there is a production of adenosine triphosphate (ATP) in cellular metabolism by the involvement of a proton gradient across a membrane
https://openstax.org/books/biology/pages/7-key-terms
citric acid cycle : (also, Krebs cycle) series of enzyme-catalyzed chemical reactions of central importance in all living cells
https://openstax.org/books/biology/pages/7-key-terms
dephosphorylation : removal of a phosphate group from a molecule
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fermentation : process of regenerating NAD+with either an inorganic or organic compound serving as the final electron acceptor, occurs in the absence; occurs in the absence of oxygen
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GLUT protein : integral membrane protein that transports glucose
https://openstax.org/books/biology/pages/7-key-terms