Test 2 Flashcards
Visible light is passed through a specimen and then through glass lenses
Light microscope
Ratio of an object’s image size to its real size
Magnification
Clarity of the image, or the minimum distance of two distinguishable points
Resolution
Visible differences in brightness between parts of the sample
Contrast
The membrane enclosed structures in eukaryotic cells
Organelles
Focuses a beam of electrons onto the surface of a specimen, providing images that look 3D
Scanning electron microscope
Focuses a beam of electrons through a specimen
Transmission electron microscope
A selective barrier that allows sufficient passage of oxygen, nutrients, and waste to service the volume of every cell
Plasma membrane
Contains most of the DNA in a eukaryotic cell
Nucleus
Encloses the nucleus, separating it from the cytoplasm
Nuclear envelope
Lines the nuclear envelope, composed of intermediate filaments and other proteins
Nuclear Lamina
Process by which cell’s recycle own organelles and macromolecules
Autophagy
Found in many fresh water protists, pump excess water out of cells
Contractile vacuoles
Found in many mature plant cells, hold organic compounds and water
Central vacuoles
Sites of cellular respiration
Mitochondria
Sites of photosynthesis
Chloroplasts
Suggests that an early ancestor of eukaryotes engulfed an oxygen using non photosynthetic prokaryotic cell
Endosymbiote theory
A cellular structure consisting of one DNA molecule and associated protein molecules.
Chromosome
A specialized structure in the nucleus, consisting of chromosomal regions containing ribosomal RNA (rRNA) genes along with ribosomal proteins imported from the cytoplasm
Nucleolus
The collection of membranes inside and surrounding a eukaryotic cell, related either through direct physical contact or by the transfer of membranous vesicles
The endomembrane system
A membranous sac in the cytoplasm of a eukaryotic cell.
Vesicle
An extensive membranous network in eukaryotic cells, continuous with the outer nuclear membrane and composed of ribosome-studded (rough) and ribosome-free (smooth) regions.
Endoplasmic reticulum
That portion of the endoplasmic reticulum that is free of ribosomes.
Smooth ER
That portion of the endoplasmic reticulum with ribosomes attached.
Rough ER
A protein with one or more covalently attached carbohydrates.
Glycoproteins
A small membranous sac in a eukaryotic cell’s cytoplasm carrying molecules produced by the cell.
Transport vesicles
An organelle in eukaryotic cells consisting of stacks of flat membranous sacs that modify, store, and route products of the endoplasmic reticulum and synthesize some products, notably noncellulose carbohydrates.
Golgi apparatus
A membrane-enclosed sac of hydrolytic enzymes found in the cytoplasm of animal cells and some protists.
Lysosome
A type of endocytosis in which large particulate substances or small organisms are taken up by a cell.
Phagocytosis
A membrane-bounded vesicle whose specialized function varies in different kinds of cells.
Vacuole
A membranous sac formed by phagocytosis of microorganisms or particles to be used as food by the cell.
Food vacuole
An infolding of the inner membrane of a mitochondrion.
Crista
The compartment of the mitochondrion enclosed by the inner membrane and containing enzymes and substrates for the citric acid cycle, as well as ribosomes and DNA.
Mitochondrial matrix
A flattened, membranous sac inside a chloroplast
Thylakoid
A stack of membrane-bounded thylakoids in the chloroplast.
Granum
The dense fluid within the chloroplast surrounding the thylakoid membrane and containing ribosomes and DNA
Stroma
One of a family of closely related organelles that includes chloroplasts, chromoplasts, and amyloplasts
Plastid
An organelle containing enzymes that transfer hydrogen atoms from various substrates to oxygen ( O 2 ) , producing and then degrading hydrogen peroxide H 2 O 2 .
Peroxisome
A network of microtubules, microfilaments, and intermediate filaments that extend throughout the cytoplasm and serve a variety of mechanical, transport, and signaling functions.
Cytoskeleton
A protein that interacts with cytoskeletal elements and other cell components, producing movement of the whole cell or parts of the cell.
Motor protein
A hollow rod composed of tubulin proteins that makes up part of the cytoskeleton in all eukaryotic cells and is found in cilia and flagella
Microtubule
A structure present in the cytoplasm of animal cells that functions as a microtubule-organizing center and is important during cell division
Centrosome
A structure in the centrosome of an animal cell composed of a cylinder of microtubule triplets arranged in a “9+0” pattern
Centriole
A long cellular appendage specialized for locomotion.
Flagella
A short appendage containing microtubules in eukaryotic cells
Cilia
A cable composed of actin proteins in the cytoplasm of almost every eukaryotic cell, making up part of the cytoskeleton and acting alone or with myosin to cause cell contraction
Microfilament
A globular protein that links into chains, two of which twist helically about each other, forming microfilaments (actin filaments) in muscle and other kinds of cells.
Actin
A component of the cytoskeleton that includes filaments intermediate in size between microtubules and microfilaments.
Intermediate filaments
A protective layer external to the plasma membrane in the cells of plants, prokaryotes, fungi, and some protists
Cell wall
The meshwork surrounding animal cells, consisting of glycoproteins, polysaccharides, and proteoglycans synthesized and secreted by cells.
Extra cellular matrix
A glycoprotein in the extracellular matrix of animal cells that forms strong fibers, found extensively in connective tissue and bone
Collagen
A large molecule consisting of a small core protein with many carbohydrate chains attached, found in the extracellular matrix of animal cells.
Proteoglycan
An extracellular glycoprotein secreted by animal cells that helps them attach to the extracellular matrix.
Fibronectin
In animal cells, a transmembrane receptor protein with two subunits that interconnects the extracellular matrix and the cytoskeleton.
Integrin
An open channel through the cell wall that connects the cytoplasm of adjacent plant cells, allowing water, small solutes, and some larger molecules to pass between the cells.
Plasmodesmata
A type of intercellular junction between animal cells that prevents the leakage of material through the space between cells.
Tight junction
A type of intercellular junction in animal cells that functions as a rivet, fastening cells together.
Desmosome
A type of intercellular junction in animal cells, consisting of proteins surrounding a pore that allows the passage of materials between cells.
Gap junction
Having both a hydrophilic region and a hydrophobic region.
Amphipathic
The currently accepted model of cell membrane structure, which envisions the membrane as a mosaic of protein molecules drifting laterally in a fluid bilayer of phospholipids.
Fluid mosaic model
A transmembrane protein with hydrophobic regions that extend into and often completely span the hydrophobic interior of the membrane and with hydrophilic regions in contact with the aqueous solution on one or both sides of the membrane
Integral protein
A protein loosely bound to the surface of a membrane or to part of an integral protein and not embedded in the lipid bilayer.
Peripheral protein
A lipid with one or more covalently attached carbohydrates.
Glycolipid
A transmembrane protein that helps a certain substance or class of closely related substances to cross the membrane.
Transport protein
A channel protein in a cellular membrane that specifically facilitates osmosis, the diffusion of free water across the membrane.
Aquaporin
The random thermal motion of particles of liquids, gases, or solids
Diffusion
A region along which the density of a chemical substance increases or decreases.
Concentration gradient
The diffusion of a substance across a biological membrane with no expenditure of energy.
Passive transport
The diffusion of free water across a selectively permeable membrane.
Osmosis
The ability of a solution surrounding a cell to cause that cell to gain or lose water.
Tonicity
Referring to a solution that, when surrounding a cell, causes no net movement of water into or out of the cell.
Isotonic
Referring to a solution that, when surrounding a cell, will cause the cell to lose water.
Hypertonic
Referring to a solution that, when surrounding a cell, will cause the cell to take up water.
Hypotonic
Swollen or distended, as in plant cells.
Turgid
Limp. Lacking turgor
Flaccid
A phenomenon in walled cells in which the cytoplasm shrivels and the plasma membrane pulls away from the cell wall
Plasmolysis
The passage of molecules or ions down their electrochemical gradient across a biological membrane with the assistance of specific transmembrane transport proteins, requiring no energy expenditure.
Facilitated diffusion
A transmembrane protein channel that allows a specific ion to diffuse across the membrane down its concentration or electrochemical gradient.
Ion channel
A transmembrane protein channel that opens or closes in response to a particular stimulus.
Gated channel
The movement of a substance across a cell membrane against its concentration or electrochemical gradient, mediated by specific transport proteins and requiring an expenditure of energy.
Active transport
A transport protein in the plasma membrane of animal cells that actively transports sodium out of the cell and potassium into the cell.
Sodium potassium pump
An active transport protein that generates voltage across a membrane while pumping ions.
Electrogenic pump
An active transport protein in a cell membrane that uses ATP to transport hydrogen ions out of a cell against their concentration gradient, generating a membrane potential in the process.
Proton pump
The coupling of the “downhill” diffusion of one substance to the “uphill” transport of another against its own concentration gradient.
Cottansport
The cellular secretion of biological molecules by the fusion of vesicles containing them with the plasma membrane.
Exocytosis
Cellular uptake of biological molecules and particulate matter via formation of vesicles from the plasma membrane.
Endocytosis
The totality of an organism’s chemical reactions, consisting of catabolic and anabolic pathways, which manage the material and energy resources of the organism.
Metabolism
A series of chemical reactions that either builds a complex molecule (anabolic pathway) or breaks down a complex molecule to simpler molecules (catabolic pathway).
Metabolic pathway
A metabolic pathway that releases energy by breaking down complex molecules to simpler molecules.
Catabolic pathway
A metabolic pathway that consumes energy to synthesize a complex molecule from simpler molecules.
Anabolic pathway
The capacity to cause change, especially to do work
Energy
The energy associated with the relative motion of objects. Moving matter can perform work by imparting motion to other matter.
Kinetic energy
Kinetic energy due to the random motion of atoms and molecules
Thermal energy
The energy that matter possesses as a result of its location or spatial arrangement
Potential energy
Energy available in molecules for release in a chemical reaction; a form of potential energy.
Chemical energy
The principle of conservation of energy: Energy can be transferred and transformed, but it cannot be created or destroyed
First law of thermodynamics
A measure of molecular disorder, or randomness.
Entropy
The principle stating that every energy transfer or transformation increases the entropy of the universe
Second law of thermodynamics
A process that occurs without an overall input of energy
Spontaneous process
The portion of a biological system’s energy that can perform work when temperature and pressure are uniform throughout the system
Free energy
A spontaneous chemical reaction in which there is a net release of free energy.
Exergonic reaction
A nonspontaneous chemical reaction in which free energy is absorbed from the surroundings.
Endergonic reaction
In cellular metabolism, the use of energy released from an exergonic reaction to drive an endergonic reaction.
Energy coupling
An adenine-containing nucleoside triphosphate that releases free energy when its phosphate bonds are hydrolyzed
ATP
A macromolecule serving as a catalyst, a chemical agent that increases the rate of a reaction without being consumed by the reaction.
Enzyme
A chemical agent that selectively increases the rate of a reaction without being consumed by the reaction
Catalyst
The amount of energy that reactants must absorb before a chemical reaction will start
Activation energy
A process by which a chemical agent called a catalyst selectively increases the rate of a reaction without being consumed by the reaction.
Catalysis
The reactant on which an enzyme works.
Substrate
A temporary complex formed when an enzyme binds to its substrate molecule(s).
Enzyme substrate complex
The specific region of an enzyme that binds the substrate and that forms the pocket in which catalysis occurs.
Active site
Any nonprotein molecule or ion that is required for the proper functioning of an enzyme.
Cofactor
An organic molecule serving as a cofactor
Coenzyme
A substance that reduces the activity of an enzyme by entering the active site in place of the substrate, whose structure it mimics.
Competitive inhibitor
A substance that reduces the activity of an enzyme by binding to a location remote from the active site, changing the enzyme’s shape so that the active site no longer effectively catalyzes the conversion of substrate to product.
Noncompetitive inhibitor
The binding of a regulatory molecule to a protein at one site that affects the function of the protein at a different site.
Allosteric regulation
A kind of allosteric regulation whereby a shape change in one subunit of a protein caused by substrate binding is transmitted to all the other subunits, facilitating binding of additional substrate molecules to those subunits.
Cooperativity
A method of metabolic control in which the end product of a metabolic pathway acts as an inhibitor of an enzyme within that pathway.
Feedback inhibition
A catabolic process that makes a limited amount of ATP from glucose (or other organic molecules) without an electron transport chain and that produces a characteristic end product, such as ethyl alcohol or lactic acid.
Fermentation
A catabolic pathway for organic molecules, using oxygen ( O 2 ) as the final electron acceptor in an electron transport chain and ultimately producing ATP
Aerobic respiration
The catabolic pathways of aerobic and anaerobic respiration, which break down organic molecules and use an electron transport chain for the production of ATP.
Cellular respiration
A chemical reaction involving the complete or partial transfer of one or more electrons from one reactant to another
Redox reaction
The complete or partial loss of electrons from a substance involved in a redox reaction
Oxidation
The complete or partial addition of electrons to a substance involved in a redox reaction.
Reduction
The electron donor in a redox reaction.
Reducing agent
The electron acceptor in a redox reaction
Oxidizing agent
The oxidized form of nicotinamide adenine dinucleotide, a coenzyme that can accept electrons, becoming NADH
NAD+
The reduced form of nicotinamide adenine dinucleotide that temporarily stores electrons during cellular respiration
NADH
A sequence of electron carrier molecules (membrane proteins) that shuttle electrons down a series of redox reactions that release energy used to make ATP
Electron transport chain
A series of reactions that ultimately splits glucose into pyruvate
Glycolysis
A chemical cycle involving eight steps that completes the metabolic breakdown of glucose molecules begun in glycolysis by oxidizing acetyl CoA (derived from pyruvate) to carbon dioxide
Citric acid cycle
The production of ATP using energy derived from the redox reactions of an electron transport chain
Oxidative phosphorylation
The enzyme-catalyzed formation of ATP by direct transfer of a phosphate group to ADP from an intermediate substrate in catabolism.
Substrate level phosphorylation
Acetyl coenzyme A
Acetyl CoA
An iron-containing protein that is a component of electron transport chains in the mitochondria and chloroplasts of eukaryotic cells and the plasma membranes of prokaryotic cells.
Cytochrome
A complex of several membrane proteins that functions in chemiosmosis with adjacent electron transport chains, using the energy of a hydrogen ion (proton) concentration gradient to make ATP
ATP sythase
An energy-coupling mechanism that uses energy stored in the form of a hydrogen ion gradient across a membrane to drive cellular work, such as the synthesis of ATP
Chemiosmosis
The potential energy stored in the form of a proton electrochemical gradient, generated by the pumping of hydrogen ions (H+) across a biological membrane during chemiosmosis.
Proton motive force
Glycolysis followed by the reduction of pyruvate to ethyl alcohol, regenerating NAD+ and releasing carbon dioxide.
Alcohol fermentation
Glycolysis followed by the reduction of pyruvate to lactate, regenerating NAD+ with no release of carbon dioxide.
Lactic acidosis fermentation
An organism that carries out only fermentation or anaerobic respiration
Obligate anaerobe
An organism that makes ATP by aerobic respiration if oxygen is present but that switches to anaerobic respiration or fermentation if oxygen is not present.
Facultative anaerobe
A metabolic sequence that breaks fatty acids down to two-carbon fragments that enter the citric acid cycle as acetyl CoA.
Beta oxidation
Leaf cells specialized for photosynthesis.
Mesophyll
A microscopic pore surrounded by guard cells in the epidermis of leaves and stems that allows gas exchange between the environment and the interior of the plant.
Stoma
The first of two major stages in photosynthesis
Light reactions
The second of two major stages in photosynthesis (following the light reactions), involving fixation of atmospheric CO 2 and reduction of the fixed carbon into carbohydrate.
Calvin cycle
The reduced form of nicotinamide adenine dinucleotide phosphate
NADPH
The process of generating ATP from ADP and phosphate by means of chemiosmosis, using a proton-motive force generated across the thylakoid membrane of the chloroplast or the membrane of certain prokaryotes during the light reactions of photosynthesis.
Photo phosphorylation
The initial incorporation of carbon from CO 2 into an organic compound by an autotrophic organism
Carbon fixation
The distance between crests of waves, such as those of the electromagnetic spectrum
Wavelength
The entire spectrum of electromagnetic radiation, ranging in wavelength from less than a nanometer to more than a kilometer.
Electromagnetic spectrum
That portion of the electromagnetic spectrum that can be detected as various colors by the human eye, ranging in wavelength from about 380 nm to about 750 nm.
Visible light
The range of a pigment’s ability to absorb various wavelengths of light
Absorption spectrum
A photosynthetic pigment that participates directly in the light reactions, which convert solar energy to chemical energy.
Chlorophyll a
An accessory photosynthetic pigment that transfers energy to chlorophyll a.
Chlorophyll b
A graph that profiles the relative effectiveness of different wavelengths of radiation in driving a particular process.
Action spectrum
An accessory pigment, either yellow or orange, in the chloroplasts of plants and in some prokaryotes
Carotenoids
A light-capturing unit located in the thylakoid membrane of the chloroplast or in the membrane of some prokaryotes, consisting of a reaction-center complex surrounded by numerous light-harvesting complexes.
Photo system
A complex of proteins associated with a special pair of chlorophyll a molecules and a primary electron acceptor
Reaction center complex
A complex of proteins associated with pigment molecules (including chlorophyll a, chlorophyll b, and carotenoids) that captures light energy and transfers it to reaction-center pigments in a photosystem.
Light harvesting complex
One of two light-capturing units in a chloroplast’s thylakoid membrane or in the membrane of some prokaryotes
Photo system II
A light-capturing unit in a chloroplast’s thylakoid membrane or in the membrane of some prokaryotes
Photo system I
A route of electron flow during the light reactions of photosynthesis that involves both photosystems (I and II) and produces ATP, NADPH, and O 2
Linear electron flow
A route of electron flow during the light reactions of photosynthesis that involves only one photosystem and that produces ATP but not NADPH or O 2 .
Cyclic electron flow
A three-carbon carbohydrate that is the direct product of the Calvin cycle
G3P
the enzyme that normally catalyzes the first step of the Calvin cycle
Rubisco
A plant that uses the Calvin cycle for the initial steps that incorporate CO 2 into organic material, forming a three-carbon compound as the first stable intermediate.
C3 plant
A metabolic pathway that consumes oxygen and ATP, releases carbon dioxide, and decreases photosynthetic output
Photorespiration
A plant in which the Calvin cycle is preceded by reactions that incorporate CO 2 into a four-carbon compound, the end product of which supplies CO 2 for the Calvin cycle.
C4 plant
In C 4 plants, a type of photosynthetic cell arranged into tightly packed sheaths around the veins of a leaf.
Bundle sheath cell
An enzyme that adds CO 2 to phosphoenolpyruvate (PEP) to form oxaloacetate in mesophyll cells of C 4 plants
PEP carboxylase
A plant that uses crassulacean acid metabolism, an adaptation for photosynthesis in arid conditions
CAM plant
