ap bio vocab chap 5

amphipathic molecule

a molecule that has both a hydrophilic region and a hydrophobic region.

concentration gradient

a region along which the density of a chemical substance increases or decreases

diffusion

the passive movement of molecules down the concentration gradient from areas of high concentration to low concentration

endocytosis

cellular uptake of biological molecules and particulate matter via formation of vesicles from the plasma membrane

exocytosis

the cellular secretion of biological molecules by the fusion of vesicles containing them with the plasma membrane

facilitated diffusion

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

flaccid

limp; lacking turgor (stiffness or firmness), as in a plant cell in surroundings where there is a tendency for water to leave the cell

fluid mosaic model

the currently accepted model of a cell membrane structure, which envisions the membrane as a mosaic of protein molecules drifting laterally in a fluid layer of phospholipids

gated channel

a transmembrane protein channel that opens or closes in response to a particular stimulus

glycolipid

a lipid with one or more covalently attached carbohydrates

glycoprotein

a protein with one or more covalently attached carbohydrates

hypertonic

referring to a solution that, when surrounding a cell, will cause the cell to lose water

hypotonic

referring to a solution that, when surrounding a cell, will cause the cell to take up water

integral protein

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 (or lining the channel in the case of a channel protein)

ion channel

a transmembrane protein channel that allows a specific ion to diffuse across the membrane down its concentration or electrochemical gradient

isotonic

referring to a solution that, when surrounding a cell, causes no net movement of water into or out of the cell

membrane potential

the difference in electrical charge (voltage) across a cell's plasma membrane due to the differential distribution of ions; affects the activity of excitable cells and the transmembrane movement of all charged substances

osmoregulation

regulation of solute concentrations and water balance by a cell or organism

osmosis

the diffusion of free water molecules across a selectively permeable membrane

passive transport

the diffusion of a substance across a biological membrane with no expenditure of energy

peripheral 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

phagocytosis

a type of endocytosis in which large particulate substances or small organisms are taken up by a cell; carried out by some protists and by certain immune cells of animals

pinocytosis

a type of endocytosis in which the cell ingests extracellular fluid and its dissolved solutes

plasmolysis

a phenomenon in walled cells in which the cytoplasm shrivels and the plasma membrane pulls away from the cell wall; occurs when the cell loses water to a hypertonic environment

proton 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

receptor-mediated endocytosis

the movement of specific molecules into a cell by the inward budding of 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 them to regulate the passage of substances across them

sodium-potassium pump

a transport protein in the plasma membrane of animal cells that actively transports sodium out of the cell and potassium into the cell

tonicity

the ability of a solution surrounding a cell to cause that cell to gain or lose water

transport protein

a transmembrane protein that helps a certain substance or class of closely related substances to cross the membrane

turgid

swollen or distended, as in plant cells

channel proteins

has a hydrophilic channel that certain molecules or ions can use as a tunnel

Aquaproteins

channel proteins that facilitate the passage of water

carrier proteins

a protein that transports substances across a cell membrane

turgor pressure

The pressure that water molecules exert against the cell wall

active transport

Energy-requiring process that moves material across a cell membrane against a concentration difference

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 membrane and its tendency to move relative to the membrane potential.

electrogenic pump

a transport protein that generates voltage across a membrane

Contransport

The coupling of the "downhill" diffusion of one substance to the "uphill" transport of another against its own concentration gradient.

transport

the means by which ions or other molecules are transported or transferred across a membrane

enzymatic activity

A protein built into the membrane with active site exposed.

Attachment to cytoskeleton and ECM

Maintains cell shape and stabilize cells.

cell-cell recognition

The function of membrane proteins in which some glycoproteins serve as ID tags that are recognized by membrane proteins of other cells.

Interceullular joining

hook to junctions of other adjacent cells

signal transduction

has binding site to fit certain chemical to relay a chemical message/ signaling molecules create shape change in proteins, and then they relay a message