Shared Flashcard Set

Details

cell,membrane,enzymes defs
cell, membrane, enzymes defs
78
Biology
Not Applicable
06/20/2008

Additional Biology Flashcards

 


 

Cards

Term
antibody
Definition
A specific protein (immunoglobulin) that recognizes and binds to specific antigens; produced by plasma cells
Term
apoptosis
Definition
Programmed cell death; apoptosis is a normal part of an organism's development and maintenance. Compare with necrosis
Term
basal body
Definition
Structure involved in the organization and anchorage of a cilium or flagellum. Structurally similar to a centriole; each is in the form of a cylinder composed of nine triplets of microtubules (9 x 3 structure).
Term
carotenoids
Definition
A group of yellow to orange plant pigments synthesized from isoprene subunits; include carotenes and xanthophylls.
Term
cell fractionation
Definition
The technique used to separate the components of cells by subjecting them to centrifugal force. See differential centrifugation and density gradient centrifugation.
Term
cell signaling
Definition
Mechanisms of communication between cells. Cells can signal one another with secreted signaling molecules, or a signaling molecule on one cell can combine with a receptor on another cell. Examples include the synaptic signaling of neurons and endocrine signaling. See signal transduction.
Term
cell theory
Definition
The theory that the cell is the basic unit of life, of which all living things are composed, and that all cells are derived from preexisting cells.
Term
cell wall
Definition
The structure outside the plasma membrane of certain cells; may contain cellulose (plant cells), chitin (most fungal cells), peptidoglycan and/or lipopolysaccharide (most bacterial cells), or other material.
Term
cellulose
Definition
A structural polysaccharide composed of beta glucose subunits; the main constituent of plant primary cell walls.
Term
centrifuge
Definition
A device used to separate cells or their components by subjecting them to centrifugal force.
Term
centriole
Definition
One of a pair of small, cylindrical organelles lying at right angles to each other near the nucleus in the cytoplasm of animal cells and certain protist and plant cells; each centriole is in the form of a cylinder composed of nine triplets of microtubules (9 x 3 structure).
Term
chlorophyll
Definition
A group of light-trapping green pigments found in most photosynthetic organisms.
Term
chloroplasts
Definition
Membranous organelles that are the sites of photosynthesis in eukaryotes; occur in some plant and algal cells.
Term
chromatin
Definition
The complex of DNA and protein that makes up eukaryotic chromosomes.
Term
cisternae
Definition
Stacks of flattened membranous sacs that make up the Golgi complex.
Term
cristae
Definition
Shelflike or finger-like inward projections of the inner membrane of a mitochondrion.
Term
cytoplasm
Definition
The plasma membrane and cell contents with the exception of the nucleus.
Term
cytoskeleton
Definition
The dynamic internal network of protein fibers that includes microfilaments, intermediate filaments, and microtubules.
Term
density gradient centrifugation
Definition
Procedure in which cellular components are placed in a layer on top of a density gradient, usually made up of a sucrose solution and water. Cell structures migrate during centrifugation, forming a band at the position in the gradient where their own density equals that of the sucrose solution.
Term
differential centrifugation
Definition
Separation of cellular particles according to their mass, size, or density. In differential centrifugation the supernatant is spun at successively higher revolutions per minute.
Term
electron microscope
Definition
A microscope capable of producing high- resolution, highly magnified images through the use of an electron beam (rather than light). Transmission electron microscopes (TEMs) produce images of thin sections; scanning electron microscopes (SEMs) produce images of surfaces.
Term
endoplasmic reticulum (ER)
Definition
An interconnected network of internal membranes in eukaryotic cells enclosing a compartment, the ER lumen. Rough ER has ribosomes attached to the cytosolic surface; smooth ER, a site of lipid biosynthesis, lacks ribosomes.
Term
extracellular matrix
Definition
The ground substance, fibrous proteins, and other materials between cells of animal tissues (e.g., cartilage).
Term
flagellum
Definition
A long, whiplike structure extending from certain cells and used in locomotion. (1) Eukaryote flagella are composed of two central single microtubules surrounded by nine double microtubules (9 + 2 structure), all covered by a plasma membrane. (2) Prokaryote flagella are filaments rotated by special structures located in the plasma membrane and cell wall.
Term
Golgi complex
Definition
Organelle composed of stacks of flattened, membranous sacs. Mainly responsible for modifying, packaging, and sorting proteins that will be secreted or targeted to other organelles of the internal membrane system or to the plasma membrane; also called Golgi body or Golgi apparatus.
Term
granum
Definition
A stack of thylakoids within a chloroplast.
Term
integrins
Definition
Receptor proteins that bind to specific proteins in the extracellular matrix and to membrane proteins on adjacent cells; transmit signals into the cell from the extracellular matrix.
Term
lysosomes
Definition
Intracellular organelles present in many animal cells; contain a variety of hydrolytic enzymes.
Term
matrix
Definition
(1) In cell biology, the interior of the compartment enclosed by the inner mitochondrial membrane; (2) In zoology, nonliving material secreted by and surrounding connective tissue cells; contains a network of microscopic fibers.
Term
microfilaments
Definition
Thin fibers composed of actin protein subunits; form part of the cytoskeleton.
Term
microtubules
Definition
Hollow cylindrical fibers composed of tubulin protein subunits; major components of the cytoskeleton and found in mitotic spindles, cilia, flagella, centrioles, and basal bodies.
Term
microvilli
Definition
Minute projections of the plasma membrane that increase the surface area of the cell; found mainly in cells concerned with absorption or secretion, such as those lining the intestine or the kidney tubules.
Term
mitochondria
Definition
Intracellular organelles that are the sites of oxidative phosphorylation in eukaryotes; include an outer membrane and an inner membrane.
Term
peroxisomes
Definition
Membrane-bounded organelles in eukaryotic cells containing enzymes that produce or degrade hydrogen peroxide.
Term
photosynthesis
Definition
The biological process that captures light energy and transforms it into the chemical energy of organic molecules (e.g., carbohydrates), which are manufactured from carbon dioxide and water; performed by plants, algae, and certain bacteria.
Term
plasma membrane
Definition
The selectively permeable surface membrane that encloses the cell contents and through which all materials entering or leaving the cell must pass.
Term
plastids
Definition
A family of membrane-bounded organelles occurring in photosynthetic eukaryotic cells; include chloroplasts, chromoplasts, and amyloplasts and other leukoplasts.
Term
ribosomes
Definition
Organelles that are part of the protein synthesis machinery of both prokaryotic and eukaryotic cells; consist of a larger and smaller subunit, each composed of ribosomal RNA (rRNA) and ribosomal proteins.
Term
stroma
Definition
A fluid space of the chloroplast, enclosed by the chloroplast inner membrane and surrounding the thylakoids; site of the reactions of the Calvin cycle.
Term
transport vesicles
Definition
Small cytoplasmic vesicles that move substances from one membrane system to another.
Term
tonoplast
Definition
The membrane surrounding a vacuole.
Term
active transport
Definition
All forms of transport of a substance across a membrane that do not rely on the potential energy of a concentration gradient for the substance being transported and therefore require an additional energy source (often ATP); includes carrier-mediated active transport, endocytosis, and exocytosis. Compare with diffusion and facilitated diffusion.
Term
adhering junction
Definition
A type of anchoring junction between cells; connects epithelial cells.
Term
amphipathic molecule
Definition
A molecule containing both hydrophobic and hydrophilic regions.
Term
carrier-mediated active transport
Definition
Transport across a membrane of a substance from a region of low concentration to a region of high concentration; requires both a transport protein with a binding site for the specific substance and an energy source (often ATP).
Term
cell signaling
Definition
Mechanisms of communication between cells. Cells can signal one another with secreted signaling molecules, or a signaling molecule on one cell can combine with a receptor on another cell. Examples include the synaptic signaling of neurons and endocrine signaling. See signal transduction.
Term
concentration gradient
Definition
A difference in the concentration of a substance from one point to another, as for example, across a cell membrane.
Term
desmosomes
Definition
Button-like plaques, present on two opposing cell surfaces, that hold the cells together by means of protein filaments that span the intercellular space.
Term
diffusion
Definition
The net movement of particles (atoms, molecules, or ions) from a region of higher concentration to a region of lower concentration (i.e., down a concentration gradient), resulting from random motion. Compare with facilitated diffusion and active transport.
Term
endocytosis
Definition
The active transport of substances into the cell by the formation of invaginated regions of the plasma membrane that pinch off and become cytoplasmic vesicles. Compare with exocytosis.
Term
erythrocyte
Definition
A vertebrate red blood cell; contains hemoglobin, which transports oxygen.
Term
exocytosis
Definition
The active transport of materials out of the cell by fusion of cytoplasmic vesicles with the plasma membrane. Compare with endocytosis.
Term
facilitated diffusion
Definition
The passive transport of ions or molecules by a specific carrier protein in a membrane. As in simple diffusion, net transport is down a concentration gradient, and no additional energy has to be supplied. Compare with diffusion and active transport.
Term
fluid-mosaic model
Definition
The currently accepted model of the plasma membrane and other cell membranes, in which protein molecules float in a phospholipid bilayer.
Term
gap junction
Definition
Structure consisting of specialized regions of the plasma membrane of two adjacent cells; contains numerous pores that allow the passage of certain small molecules and ions between them.
Term
osmosis
Definition
The net movement of water (the principal solvent in biological systems) by diffusion through a selectively permeable membrane from a region of higher concentration of water (a hypotonic solution) to a region of lower concentration of water (a hypertonic solution).
Term
pinocytosis
Definition
Cell drinking; a type of endocytosis by which cells engulf and absorb droplets of liquids.
Term
receptor-mediated endocytosis
Definition
A type of endocytosis in which extracellular molecules become bound to specific receptors on the cell surface and then enter the cytoplasm enclosed in vesicles.
Term
sodium-potassium pump
Definition
Active transport system that transports sodium ions out of, and potassium ions into, cells.
Term
tight junctions
Definition
Specialized structures that form between some animal cells, producing a tight seal that prevents materials from passing through the spaces between the cells.
Term
turgor pressure
Definition
Hydrostatic pressure that develops within a walled cell, such as a plant cell, when the osmotic pressure of the cell's contents is greater than the osmotic pressure of the surrounding fluid.
Term
adenosine triphosphate (ATP)
Definition
An organic compound containing adenine, ribose, and three phosphate groups; of prime importance for energy transfers in cells.
Term
anabolism
Definition
The aspect of metabolism in which simpler substances are combined to form more complex substances, resulting in the storage of energy, the production of new cellular materials, and growth. Compare with catabolism.
Term
catabolism
Definition
The aspect of metabolism in which complex substances are broken down to form simpler substances; catabolic reactions are particularly important in releasing chemical energy stored by the cell. Compare with anabolism.
Term
coenzyme
Definition
An organic cofactor for an enzyme; generally participates in the reaction by transferring some component, such as electrons or part of a substrate molecule.
Term
competitive inhibitor
Definition
A substance that binds to the active site of an enzyme, thus lowering the rate of the reaction catalyzed by the enzyme. Compare with noncompetitive inhibitor.
Term
endergonic reaction
Definition
A nonspontaneous reaction; a reaction requiring a net input of free energy. Compare with exergonic reaction.
Term
entropy
Definition
Disorderliness; a quantitative measure of the amount of the random, disordered energy that is unavailable to do work.
Term
enzyme-substrate complex
Definition
The temporary association between enzyme and substrate that forms during the course of a catalyzed reaction; also called ES complex.
Term
exergonic reaction
Definition
A reaction characterized by a release of free energy. Also called spontaneous reaction. Compare with endergonic reaction.
Term
feedback inhibition
Definition
A type of enzyme regulation in which the accumulation of the product of a reaction inhibits an earlier reaction in the sequence; also known as end product inhibition.
Term
first law of thermodynamics
Definition
The law of conservation of energy, which states that the total energy of any closed system (any object plus its surroundings, i.e., the universe) remains constant. Compare with second law of thermodynamics.
Term
free energy
Definition
The maximum amount of energy available to do work under the conditions of a biochemical reaction.
Term
NADP+/NADPH
Definition
Oxidized and reduced forms, respectively, of nicotinamide adenine dinucleotide, a coenzyme that transfers electrons (as hydrogen), particularly in catabolic pathways, including cellular respiration
Term
noncompetitive inhibitor
Definition
A substance that lowers the rate at which an enzyme catalyzes a reaction but does not bind to the active site. Compare with competitive inhibitor.
Term
oxidation
Definition
The loss of one or more electrons (or hydrogen atoms) by an atom, ion, or molecule. Compare with reduction.
Term
reduction
Definition
The gain of one or more electrons (or hydrogen atoms) by an atom, ion, or molecule. Compare with oxidation.
Term
second law of thermodynamics
Definition
The physical law that states that the total amount of entropy in the universe continually increases. Compare with first law of thermodynamics.
Supporting users have an ad free experience!