membrane structure & transport

cells unit test quizlet

functions of plasma membrane

act as a semi- or selectively permeable barrier to allow materials to move into and out of the cell, allow cells to communicate, allow protection of cells

phospholipid bilayer

Plasma membrane layers composed of phospholipid molecules arranged with polar heads facing the outside and nonpolar tails facing the inside.

hydrophilic

water loving; polar

hydrophobic

water hating; non-polar

phospholipid

A molecule that makes up biological membranes, having a polar, hydrophilic head and a nonpolar, hydrophobic tail.

selectively permeable aka semi-permeable

property of biological membranes that allows some substances to pass across it while others cannot

fluid mosaic model

model that describes the arrangement and movement of the molecules that make up a cell membrane

passive transport

the movement of substances across a cell membrane without the use of energy by the cell

active transport

the movement of materials through a cell membrane using energy (ATP)

Equilibrium

A state of balance where there are equal concentrations on both sides of a membrane

concentration gradient

A difference in the concentration of a substance across a semi-permeable membrane

diffusion

Movement of molecules through the phospholipids from an area of higher concentration to an area of lower concentration; passive transport

osmosis

Movement of water through the phospholipids and through aquaporins from an area of higher concentration to an area of lower concentration; passive transport

facilitated diffusion

Movement of molecules through the carrier protein channels from an area of higher concentration to an area of lower concentration; passive transport

hypertonic solution

A solution in which the concentration of solutes is greater than that of the cell that resides in the solution; causes water to move out of cells

hypotonic solution

A solution in which the concentration of solutes is less than that of the cell that resides in the solution; causes water to move into cells

isotonic solution

A solution in which the concentration of solutes is equal to that of the cell which resides in the solution; causes water to move into and out of cells at equal rates

protein pumps

transport proteins that require energy to move ions against their concentration gradient; type of active transport

exocytosis

release of substances out a cell by the fusion of a vesicle with the membrane; type of active transport

endocytosis

taking in a substance by a cell wrapping its membrane around the material; type of active transport

receptor protein

a protein that binds specific signal molecules, which causes the cell to respond; on the outside of a cell's membrane

signal protein

A protein that is used to communicate with other cells to elicit a response; attaches to a specific receptor protein on the outside of a cell's membrane

intracellular

within/inside the cell

extracellular

outside the cell

permeable

Able to be passed through

impermeable

not permitting passage

with the concentration gradient

from high to low concentration

against the concentration gradient

from low to high concentration

peripheral protein

a protein appendage loosely bound to the surface of a membrane and not embedded in the lipid bilayer; often used as anchors

cholesterol in plasma membrane

hydrophilic and located on the inner side of the plasma membrane between the phospholipid tails; maintains membrane fluidity

aquaporin

water channel protein in a cell

cytoskeleton filaments

long protein chains in the cytoplasm that help the cell hold its shape. organelles and other large molecules can travel along these chains like super highways in the cell

glycoprotein

A protein with one or more carbohydrates/sugars attached to it; on the outside of the cell membrane; serve a function of cellular identification

vesicle

A membrane bound sac that contains materials involved in transport of the cell.

integral protein

Typically transmembrane proteins with hydrophobic regions that completely span the hydrophobic interior of the membrane

trans-membrane channel protein

span the membrane between the intracellular and extracellular environments; specifically move particles across the membrane

solvent

In a solution, the substance in which the solute dissolves; water

solute

A substance that is dissolved in a solvent when making a solution