Unit 2

the movement of ions or molecules across a membrane in a single direction, often against a gradient; requires energy (from hydrolysis of ATP) and assistance of a transport protein

a type of channel protein that facilitates the movement of water (osmosis) across a plasma membrane

a transmembrane protein that facilitates diffusion of a small molecule (like glucose) across a membrane by a process involving reversible change in the shape of a protein

a transmembrane protein that forms a pore in a cell membrane, which may open or close in response to a signal; structure of most allows them to admit just one or a few types of ions or molecules

difference across a plane (across a membrane) in the concentration of a dissolved substance

spontaneous movement of a substance from one region to another, often with a net movement from a region of high concentration to low concentration (down a concentration gradient)

the combined effect of an ion’s concentration gradient and electrical (charge) gradient across a membrane that affects the diffusion of ions

passive movement (diffusion) of a substance across a membrane with the assistance of transmembrane carrier proteins or channel proteins

the widely accepted hypothesis that cellular membranes consist of proteins embedded in a fluid phospholipid bilayer

the technical field of using microscopes to view objects and areas of objects that can’t be seen with the naked eye

a channel protein that opens and closes in response to a specific stimulus, such as the binding of a particular substance or a change in voltage across a membrane

a wide group of membrane proteins that facilitate the transport of glucose across the plasma membrane (process known as facilitated diffusion)

comparative term designating a solution that, if outside a cell or vesicle, results in the loss of water and shrinkage of the membrane-bound structure; the solution has a greater solute concentration than the solution on the other side of the membrane; used when solute is unable to pass through the membrane

comparative term designating a solution that, if outside a cell or vesicle, results in the uptake of water and swelling or even bursting of the membrane-bound structure; has a lower solute concentration than the solution on th either side of membrane

any membrane protein that spans the entire lipid bilayer; also called transmembrane protein

a type of channel protein that allows certain ions to diffuse across a plasma membrane down an electrochemical gradient

comparative term designating a solution that, if inside a cell or vesicle, results in no net uptake or loss of water and thus no effect on the volume of the membrane-bound structure; has the same solute concentration as the solution on the other side of the membrane

the basic structural elements of all cellular membranes; consists of a 2-layer sheet of phospholipid molecules with their hydrophobic tails oriented toward the inside and hydrophilic heads toward the outside

term used to describe the ease of movement of molecules in the membrane; an important characteristic for cell function

diffusion of water across a selectively permeable membrane from a region of low solute concentration (high water concentration) to high solute concentration (low water concentration); for it to occur, solute would not be able to pass through the membrane

diffusion of a substance across a membrane; requires no energy; when it occurs with the assistance of membrane proteins, it’s called facilitated diffusion

any membrane protein that does not span the entire lipid bilayer but instead binds to only one side of the bilayer

the tendency of a structure, such as a membrane, to allow a given substance to diffuse across it

a class of lipid having a hydrophilic head (including phosphate group) and a hydrophobic tail (including 2 hydrocarbon chains); major component of plasma and organelle membranes

a hypothetical pre-cell structure consisting of a membrane compartment that encloses replicating macromolecules (such as ribozymes)

the property of a membrane that allows some substances to diffuse across it much more readily than other substances

a transmembrane protein that uses the energy of ATP to move sodium ions out of the cell and potassium ions into the cell, normally against electrochemical gradients (also called Na+/K+ - ATPase+ - ATPase)

any membrane protein that spans the entire lipid bilayer; also called integral membrane protein

proteins that transport substances across biological membranes; allow for selective passage of specific molecules from the external environment

a long fiber composed of two intertwined strands of polymerized actin protein; 1 of 3 types of cytoskeleton fibers; involved in cell movement — same as microfilament

a fibrous layer found outside the plasma membrane of most bacteria and archaea and many eukaryotes

small cylindrical structures, in centrosome near nucleus of eukaryote cell; consists of microtubule triplets

a chlorophyll-containing organelle bounded by double membrane in which photosynthesis occurs; found in plants and algae

one of many short, filament outs projections of some eukaryotic cells, containing a core of microtububles; used to move cell as well as circulate fluid or particles around the surface of stationary cell

flattened, membrane-bound compartments that make up golgi apparatus

sac-like folds of the inner membrane of a mitochondria; location of electron transport chain and ATP synthase

the fluid portion of the cytoplasm, excluding the contents of membrane-enclosed organelles

a class of motor proteins that uses ATP to “walk” toward the minus end of a microtubule; responsible for bending of cilia and flagella, play a role in chromosome movement during mitosis, and can transport vesicles and organelles

general term for any pinching off of plasma membrane that results in uptake of material from outside of the cell (phagocytosis, pinocytosis, etc.)

the theory that mitochondria and chloroplasts evolved from prokaryotes engulfed by host cells and took up symbiotic existence within those cells

secretion of intracellular molecules (hormones, collagen, etc.) contained within membrane-bound vesicles to the outside of the cell by fusion of vesicles to the plasma membrane

any protein with one or more covalently bonded carbohydrates, typically oligosaccharides

organelle consisting of stacks of flattened mebranous sacs (cisternae) that functions in processing and sorting proteins and lipids destined to be secreted or directed to other organelles

a long fiber composed of one of various proteins (keratins, lamins, etc.); 1 of 3 types of cytoskeleton fibers; used to form networks that help maintain cell shape and hold nucleus in place

a class of motor proteins that uses ATP to “walk” toward the plus end of a microtubule; transports vesicles, particles, organelles, and chromosomes

organelle that rids cells of waste products and breaks down macromolecueles (carbs, lipids, proteins, nucleic acids)

a long fiber composed of two intertwined strands of polymerized actin protein; 1 of 3 types of cytoskeleton fibers; involved in cell movement — same as actin filament

a long, tubular fiber formed by polymerization of tubulin protein dimers; 1 of 3 types of cytoskeleton fibers; involved in cell movement and transport of materials within cell

central compartment of mitochondria, lined by inner membrane; contains mitochondrial DNA, ribosomes, and enzymes

class of proteins whose major function is to convert the chemical energy of ATP into motion — includes dynein, kinesin, and myosin

in prokaryotic cells, a dense, centrally located region that contains DNA but is not surrounded by a membrane

uptake by a cell of small particles or cells by folding and pinching off of the plasma membrane to form small, membrane-bound vesicles; one type of endocytosis

uptake by a cell of certain extracellular macromolecules, bound to specific receptors in the plasma membrane by pinching off the membrane to form small membrane-bound vesicles

portion of ER dotted with ribosomes; involved in synthesis of plasma membrane proteins, secreted proteins, and proteins localized to the ER, golgi apparatus, and lysosomes

portion of ER that lacks attached ribosomes; involved in synthesis and secretion of lipids

fluid matrix of a chloroplast enclosed within a double membrane envelope in which the thylakoids are embedded

a membrane-bound network of flattened sac-like structures inside a plant chloroplast that functions in converting light energy to chemical energy

general term for a disease caused by cells that grow in an uncontrolled fashion, invade nearby tissues, and spread to other sites in the body

an ordered sequence of events in which a eukaryotic cell increases in size, replicates its chromosomes, evenly partitions the chromosomes to 2 daughter nuclei, and then undergoes division of the cytoplasm

formation of new cells by division of preexisting cells

any of several points in the cell cycle at which progression of a cell through the cycle can be regulated

any of several related protein kinases that are functional only when bound to a cyclin and are activated by other modifications; involved in control of cell cycle

one of several regulatory proteins whose concentrations fluctuate cyclically throughout the cell cycle; involved in control of cell cycle via cdk’s

the phase of cell cycle that constitutes the first part of interphase, before DNA synthesis/S phase

the phase of cell cycle between synthesis of DNA (S phase) and mitosis (M phase); last part of interphase

the phase of the cell cycle during which DNA is synthesized for the replication of chromosomes

the phase of cell cycle during which cell division occurs; includes mitosis or meiosis and often cytokinesis

a tumor-suppressor protein that responds to DNA damage by stopping the cell cycle, turning on DNA repair machinery, and, if necessary, triggering apoptosis; encoded by p53 gene

a protein that prevents cell division when conditions are unfavorable, such as when the cell has DNA damage; defects in function of tumor suppressors (like p53) are associated with uncontrolled cell replication in cancer

any gene that encourages cell division in a regulated manner, typically by triggering specific phases in the cell cycle; mutation may convert it to an oncogene