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207 Cards in this Set

  • Front
  • Back
Activation Energy
the amount of energy that reactants must absorb before a chemical reaction will start
Active Site
the specific portion of an enzyme that attaches to the substrate by means of weak chemical bonds
Allosteric Site
a specific receptor site on an enzyme molecule remote from the active site
Anabolic Pathways
a metabolic pathway that synthesizes a complex molecule from simpler compounds
ATP (adenosine triphosphate)
an adenine-containing nucleoside triphospate that releases free energy when its phosphate bonds are hydrolyzed
Catabolic Pathway
a metabolic pathway that releases energy by breaking down complex molecules into simpler compounds
a metabolic pathway that synthesizes a complex molecule from simpler compounds
Chemical Energy
energy stored in the chemical bonds of molecules; a form of potential energy
Competitive Inhibitor
a substance that reduces the activity of an enzyme by entering the active site in place of the substrate whose structure it mimics
Endergonic Reaction
a non spontaneous chemical reaction in which free energy is absorbed from the surroundings
Energy Coupling
the use of an exergonic process to drive an endergonic one
the capacity to do work by moving matter against an opposing force
Exergonic Reaction
a non spontaneous chemical reaction in which free energy is expelled from the cell
a quantitive measure of disorder or randomness; symbolized by s
Feedback Inhibition
a method of metabolic control in which the end-product of a metabloic pathway acts as in inhibitor of an enzyme within that pathway
Free Energy of Activation
the initial investment of energy necessary to start a chemical reaction
Free Energy
a quantity of energy that interrelates entropy and the system's total energy
Induced Fit
the change in shape of the active aite of an enzyme so that it binds more snugly to the substrate, induced by entry of the substrate
Kinetic Energy
the energy of motion, which is directly related to the speed of that motion
the totality of an organism's chemical processes, consisting of catabolic and anabolic pathways
Noncompetitive Inhibitor
a substance that reduces the activity of an enzyme by binding to a location remote from the active site, changing its conformation so that it no longer binds to the substrate
the recipient of the phosphate group
Potential Energy
the energy stored by matter as a result of its location or spatial arrangement
the substances on which an enzyme works
the study of the energy transformations that occur in a collection of matter
a globular protein that links into chains, two of which twist helically about each other, forming microfilaments in muscle and other contractile elements in cells
Basal Body
a eucharistic cell organelle consisiting of a 9+0 arrangement of microtuble triplets; may organize the microtubule assembly of a cilium or flagellum; structurally identical to a centriole
Cell Fractionation
the disruption of a cell and separation of its organelles by centrifugaion
Cell Wall
a protective layer external to the plasma membrane in plant cells, bacteria, fungi, and some protists
Central Vacuole
a place to store organic compounds
material present in the cytoplasm of all eucharistic cells and important during cell division
an organelle found only in plants and photosynthetic protists that absorbs sunlight and uses it to drive the synthesis of organic compounds from carbon dioxide and water
the comples of DNA and proteins that makes up a eukaryotic chromosome
a threadlike, gene-carrying structure found in the nucleus
a short cellular appendage specialized for locomotion, formed from a core of nine outer doublet microtubles and two innter single microtubules unsheathed in an extension of plasma membrane
a glycoprotein in the extracellular matrix of animal cells the forms strong fibers, found extensively in connective tissue and bond; the most abundant protein in the animal kingdom
Contractile Vacuole
pumps excess water out of the cell
an infolding of the inner membrane of a mitochondrion that houses the electron transport chain and the enzyme catalyzing the synthesis of ATP
the entire contents of the cell, exclusive of the nucleus, and bounded by the plasma membrane
a network of microtubules, microfilaments, and intermediate filaments that branch throughout the cytoplasm and serve a variety of mechanical and transport functions
a type of intercellular junction in animal cells that functions as an anchor
a large contractile protein forming the sidearms of microtubule doublets in cilia and flagella
Endomembrane System
the collection of membranes inside and around a eukaryotic cell, related either through direct physical contact or by the transfer of membranous vesicles
Endoplasmic Reticulum (ER)
an extensive membranous network in eukaryotic cells, continuous with other nuclear membrane and composed of ribosome-studded (rough) and ribosome-free (smooth) regions
Extracellular Matrix (ECM)
the substance in which animal tissue cells are embedded; consists of protein and polysaccharides
bind to receptor proteins that are built into the plasma membrane
a long cellular appendage specialized for locomotion, formed from a core of nine outer doublet microtubules and two inner single microtubules, unsheathed in an extension of plasma membrane
Gap Junction
a type of intercellular junction in animal cells that allows the passage of material or current between cells
a protein with covalently attached carboyhydrate
Golgl Apparatus
an organelle in eukaryotic cells consisting of stacks of flat membranous sacs that modify, store, and route products of the endoplasmic reticulum
a stacked portion of the thylakoid membrane in the chloroplast
Intermediate Filament
a compound of the cytoskeleton that includes all filaments intermediate in size between microtubules and microfilaments
Light Microscope (LM)
an optical instrument with lenses that refract visible light to magnify images of specimens
a membrane-enclosed bag of hydrolytic enzymes found in the cytoplasm of eukaryotic cells
a solid rod of actin protein in the cytoplasm of almsot all eukaryotic cells, making up part of the cytoskeleton and acting alone or with myosin to cause cell contraction
a hollow rod of tubulin protein in the cytoplasm of all eukaryotic cells in the cilia, flagella, and the cytoskeleton
Middle Lamella
a thin layer of adhesive extracellular material, primarily pectins, found between the primary walls of adjacent young plant cells
Mitochondria Matrix
the compartment of the mitochondrion enclosed by the inner membrane and containing enzymes and substrates for the Krebs cycle
an organelle in eukaryotic cells that serves as the site of cellular respiration
a type of protein filament that interacts with actin filaments to cause cell contraction
Nuclear Lamina
a netlike array of protein filaments that maintains the shape of the nucleus
a specialized structure in the nucleus, formed from various chromosomes and active in the synthesis of ribosomes
one of several formed bodies with a specialized functions, suspended in the cytoplasm and found in eukaryotic cells
a microbody containing enzymes that transfer hydrogen from various substrates to oxygen, producing and then degrading hydrogen peroxide
a type of endocytosis involving large, particulate substances
Plasma Membrane
the membrane at the boundary of every cell that acts as a selective barrier, thereby regulating the cell's chemical composition
one of a family of closely related plant organelles, including chloroplasts, chromoplasts, and amyloplasts (leucoplasts)
Primary Cell Wall
a relatively thin and flexible wall
Prokaryotic Cell
a type of cell lacking a membrane-enclosed nucleus and membrane-enclosed organelles; found only in the domains Bacteria and Archaea
a cellular extension of amoeboid cells used in moving and feeding
Resolving Power
a measure of the clarity of an image; the minium distance that two points can be separated and still be distinguished as two separate points
a cell organelle constructed in the nucleolus, functioning as the site of protein synthesis in the cytoplasm
Rough ER
that portion of the endoplasm retiuclum studded with ribosomes
Secondary Cell Wall
a wall between the plasma membrane and the primary wall
Smooth ER
that portion of the endoplasmic reticulum that is free of ribosomes
a microscopic pore surrounded by guard cells in the epidermis of leaves and stems that allow gas exchange
a flattened membrane sac inside the chloroplast, used to convert light energy to chemical energy
Tight Junction
a type of intercellular junction in animal cells that prevents the leakage of material between cells
a membrane that encloses the central vacuole in a plant cell, separating the cytosol from the cell sap
Transport Vesicles
vesicles in transit form one part of the cell to another
fluid-filled, membrane-bound bodies
Active Transport
the movement of a substance across a biological membrane against its concentration or electrochemical gradient, with the help of energy input and specific transport proteins
Amphipathic Molecule
a molecule that has both a hydrophilic region and a hydrophobic region
a transport protein in the pasma membranes of a plant or animal cell that specifically facilitates the diffusion of water across the membrane
the coupling of the "downhill" diffusion of one substance to the "uphill" transport of another against its own concentration gradient
the spontaneous tendency of a substance to move down its concentration gradient from a more concentrated area to a less concentrated area
Electrochemical Gradient
the diffusion gradient of an ion, representing a type of potential energy that accounts for both the concentration difference of the ion across a memebrane and its tendency to move relative to the membrane potential
Electrogenic Pump
an ion transport protein generating voltage across the membrane
the cellular uptake of macromolecules and particular substances by localized regions of the plasma membrane that surround the substance and pinch off to form an intracellular vesicle
the cellular secretion of the macromolecules by the fusion of vesicles with the plasma membrane
the cellular secretion of the macromolecules by the fusion of vesicles with the plasma membrane
Facilitated Diffusion
the spontaneous passage of molecules and ions, bound to specific carrier proteins, across a biological membrane down their concentration gradients
Fluid Mosaic Model
the currently accepted model of cell membrane structure, which envisions the membrane as a mosaic of individually inserted protein molecules drifting laterally in a fluid bilayer of phospholipids
Gated Ion Channel
a specific ion channel that opens and closes to allow the cell to alter its membrane potential
Hypertonic Solution
a solution with a greater solute concentration than another, a hypertonic solution
Hypotonic Solution
a solution with a lesser solute concentration than another, a hypertonic solution
Intergral Protein
a typically transmembrane proteins with hydrophobic regions that completely span the hydrophobic interior of the membrane
Isotonic Solutions
solutions of equal solute concentration
a molecule that binds specifically to a receptor site of another molecule
Membrane Potential
the charge difference between the cytoplasm and extracellular fluid in all cells, due to the differential distribution of ions
adaptations to control the water balance in organisms living in hypertonic, hypotonic, or terrestial envrionments
the diffusion of water across a selectively permeable membrane
Passive Transport
the diffusion of a substance across a biological membrane
Peripheral Protein
protein appendages loosely bound to the surface of the membrane and not embedded in the lipid bilayer
a type of endocytosis envolving large, particulate substances
a type of endocytosis in which the cell ingests extracellular fluid and its dissolved solutes
a phenomenon in walled cells in which the cytoplasm shrivels and the plasma membrane pulls away from the cell wall when the cell loses water to a hypertonic envrionment
Proton Pump
an active transport mechanism in cell membranes that consumes ATP to force hydrogen ions out of a cell and, in the process, generates a membrane potential
Receptor-Mediated Endocytosis
the movement of specific molecules into a cell by the inward budding of membranous vesicles containing proteins with receptor sites specific to the molecules being taken in; enables a cell to acquire bulk quantities of specific substances
Selective Permeability
a property of biological membranes that allows some substances to cross more easily than others
Sodium-Potassium Pump
a special transport protein in the plasma membrane of animal cells that transports sodium out of and potassium into the cell against their concentration gradients
Transport Protein
a transmembrane protein that helps a certain substance or class of closely related substances to cross the membrane
Acid Precipitation
rain, snow, or fog that is more acidic than pH 5.6
the clinging of one substance to another
a substance that consists of acid and base forms in solution and that minimizes changes in the pH when extraneous acids or bases are added to the solution
Calorie (cal)
the amount of heat energy required to raise the temperature of 1 g of water 1 degree C; the amount of heat energy that 1 g of water releases when it cools by 1 degree C
Celsius Scale
a temperature scale (C) equal to 5/9(F-32) that measures the freezing point of water at 0 degrees C and the boiling point at 100 degrees C
the binding together of like molecules often by hydrogen bonds
Evaporative Cooling
the property of a liquid whereby the surface becomes cooler during evaporation, owing to a loss of highly kinetic molecules to the gaesous state
Heat of Vaporization
the quantity of heat a liquid must absorb for 1 g of it to be converted from the liquid to the gaseous state
the total amount of kinetic energy due to molecluar motion in a body of matter; energy in its most random form
Hydrogen Ion
a single proton with a charge of +1
having an affinity for water
having an aversion to water; tending to coalesce and form droplets of water
Hydroxide Ion
a single electron with a charge of -1
Joule (J)
a unit of energy
Kilocalorie (kcal)
a thousand calories, the amount of heat energy required to raise the temperature of 1 kg of water 1 degree C
Kinetic Energy
the energy of motion, which is directly related to the speed of that motion
a common measure of solute concentration, referring to the number of moles of solute in 1 L of solution
Mole (mol)
the number of grams of a substance that equals its molecular weight in Daltons and contains Avogadro's number of molecules
Molecular Weight
the sum of the weights of all the atoms in a molecule
a measure of hydrogen ion concentration equal to -log[H] and ranging in value from 0 to 14
Polar Molecule
a molecule with opposite charges on opposite sides
a substance that is dissolved in a solution
a homogeneous, liquid mixture of two or more substance
the dissolving agent of a solution
Specific Heat
the amount of heat that must be absorbed or lost for 1 g of a substance to change its temperature 1 degree C
Surface Tension
a measure of how difficult it is to stretch or break the surface of a liquid
a measure of the intensity of heat in degrees, reflecting the average kinetic energy of the molecules
organic compound containing hydroxyl groups
an organic molecule with a carbonyl group located at the end of the carbon skeleton
organic compounds with the amino group
Amino Group
a functional group that consists of nitrogen atom bonded to two hydrogen atoms; can act as a base in solution, accepting a hydrogen ion and acquiring a charge of +1
Carbonyl Group
a functional group present in aldehyde and ketones consisting of a carbon atom double-bonded to an oxygen atom
Carboxyl Group
a functional group present in organic acids, consisting of a single carbon atom double-bonded to an oxygen atom and also bonded to a hydroxyl group
Carboxylic Acid
organic acid
one of a pair of molecules that are mirror-image isomers of each other
Functional Group
a specific configuration of atoms commonly attached to the carbon skeleton of organic molecules and usually involved in chemical reactions
Geometric Isomer
some covalent partnerships, but differ in spatial arrangements
an organic molecule consisting only of carbon and hydrogen
Hydroxyl Group
a functional group consisting of a hydrogen atom joined to an oxygen atom by a polar covalent bond; molecules possessing this group are soluble in water and are called alcohols
one of several organic compounds with the same molecular formula but different structure and therefore different properties
an organic compound not at the end of a carbon skeleton
Organic Chemistry
the study of carbon compounds
Phosphate Group
a functional group important in energy transfer
Phosphate Group
a functional group important in energy transfer
Sulfhydryl Group
consist of sulfur atom bonded to an atom of hydrogen
organic compounds containing sulfhydryls
Alpha Helix
a spiral shape constituting one form of the secondary structure of proteins, arising from a specific hydrogen-bonding structure
Amino Acid
an organic molecule possessing both carboxyl and amino groups; serve as the monomers of proteins
Beta Pleated Sheets
one form of the secondary structure of proteins in which the polypeptide chain folds back and forth, or where two regions of the chain lie parallel to each other and are held together by hydrogen bonds
a sugar (monosaccharide) or one of its dimers (disaccharides) or polymers (polysaccharides)
a structural polysaccharide of cell walls, consisting of glucose monomers joined by B-1, 4-glycosidic linkages
a structural polysaccharide of an amino sugar found in many fungi and in the exoskeletons of all arthropods
a steroid that forms an essential component of animal cell membranes and acts as a precursor molecule for the synthesis fo other biologically important steroids
Condensation Reaction
a reaction in which two molecules become covalently bonded to each other through the loss of a small molecule, usually water; also called dehydration reaction
for proteins a process in which a protein unravels and loses its native conformation, thereby becoming bilogically inactive
Deoxyribonucleic Acid (DNA)
a double-stranded, helical nucleic acid molecule capable of replicating and determining the inherited structure of a cell's proteins
the sugar component of DNA, having one less hydroxyl group than ribose, the sugar component of RNA
a double sugar, consisting of two monosaccharides joined by dehydration synthesis
Disulfide Bridge
the conformation of a protein may be reinforced further by strong, covalent bonds
Double Helix
the form of native DNA, referring to its two adjacent polynucleotide strands wound into a spiral shape
Fat (triacylglycerol)
a biological compound consisting of three fatty acids linked to one glycerol molecule
Fatty Acid
a long carbon chain carboxylic acid
a discrete unit of hereditary information consisting of a specific nucleotide sequence in DNA (or RNA, in some viruses)
an extensively branched glucose storage polysaccharide found in the liver and muscle of animals; the animal equivalent of starch
Glycosidic Linkage
a covalent bond formed between two monosaccharides by a dehydration reaction
a chemical process that lyses or splits molecules by the addition of water
Hydrophobic Interaction
a type of weak chemical bond formed when molecules that do not mix with water coalesce to exclude the water
one of a family of compounds, including fats, phospholipids, and steroids, that are insoluble in water
a giant molecule of living matter formed by the joining of smaller molecules, usually by condensation synthesis
the subunit that serves as the building block of a polymer
the simplest carbohydrate; active alone or serving as a monomer for disaccharides and polysaccharides
Nucleic Acid (polynucleotide)
a polymer consisting of many nucleotide monomers; serves as a blueprint for proteins and, through the actions of proteins, for all cellular activites
the building block of a nucleic acid, consisting of a five-carbon sugar covalently bonded to a nitrogenous base and a phosphate group
Peptide Bond
the covalent bond between two amino acid units, formed by condensation synthesis
molecules that constitute the inner bilayer of biological membranes, having a polar, hydrophilic head and nonpolar, hydrophobic tail
molecules that constitute the inner bilayer of biological membranes, having a polar, hydrophilic head and nonpolar, hydrophobic tail
nucleotides are joined by covalent bonds called phosphodiester linkages between the phosphate of one nucleotide and the sugar of the next
a polymer of up to over a thousand monosaccharides, formed by condensation synthesis
a polymer of up to over a thousand monosaccharides, formed by condensation synthesis
Primary Structure
the level of protein structure referring to the specific sequence of amino acids
a three-dimensional biological polymer constructed from a set of twenty different monomers called amino acids
larger, with the six-membered ring fused to a five-membered ring; adenine (A) and guanine (G)
has a six-membered ring of carbon and nitrogen atoms
Quaternary Structure
the particular shape of a complex, aggregate protein, defined by the characteristic three-dimensional arrangement of its constituent subunits, each a polypeptide
Ribonucleic Acid (RNA)
a type of nucleic acid consisting of nucleotide monomers with a ribose sugar and the nitrogenous bases adenine (A), cytosine (C), guanine (G), and uracil (U); usually single-stranded; functions in protein synthesis and as the genome of some viruses
the sugar component of RNA
Saturated Fatty Acid
a fatty acid in which all carbons in the hydrocarbon tail are connected by single bonds, thus maximizing the number of hydrogen atoms that can attach to the carbon skeleton
Secondary Structure
the localized, repetitive coiling or folding of the polypeptide backbone of a protein due to hydrogen bond formation between peptide linkages
a storage polysaccharide in plants consisting entirely of glucose
a class of lipids characterized by a carbon skeleton consisting of four rings with various functional groups attached
Tertiary Structure
irregular contortions of a protein molecule due to interactions of side chains involved in hydrophobic interactions, ionic bonds, hydrogen bonds and disulfide bridges
Unsaturated Fatty Acids
a fatty acid possessing one or more double bonds between the carbons in the hydrocarbon tail; such bonding reduces the number of hydrogen atoms attached to the carbon skeleton
X-Ray Crystallography
the study of crystal structure by means of x-ray diffraction