2.1-2.5 : gas exchange and membrane transport unit 1

active transport

the active movement of substances from a low concentration to a higher concentration (up their concentration gradient) with the use of energy in the form of ATP

adenosine triphosphate (ATP)

the universal energy carrier found in all living cells

aliveoli

small air sacs found in the lungs at the end of bronchioles which provide a large surface area for gas exchange

carrier protein

protein involved in active transport that uses energy in the form of ATP to change conformation

cell membrane

the semi permaeble membrane surrounding a cell’s cytoplasm

channel protein

a transmembrane protein that can transport large or charged substances some are involved in facilitated diffusion and do not use ATP; others are involved in active transport and do require energy in the form of ATP

diffusion

the passive spreading out of substances from a high concentration to a lower concentration (down their concentration gradient) without the use of energy

endocytosis

the bulk uptake of substances into a cell by invagination of the membrane to form a vesicle trapping the substances inside the cell with the use of energy in the form of ATP

exocytosis

the bulk transport of substance out of a cell using a vesicle that fuses with the plasma membrane using energy in the form of ATP

facilitated diffusion

the net movement of substances form a high concentration to a lower concentration (down their concentration gradient) through transport proteins without the use of energy

fluid mosaic model

a model that describes membrane structure as a sea of mobile phospholipids studded with various proteins

osmosis

the net movement of water molecules across a partially permeable membrane form a region of high water concentration to a region of a lower water concentration without the use of energy

passive transport

a process by which an ion or molecule passes through a cell wall via a concentration gradient, without the use of energy, this can happen via simple or facilitated diffusion ,osmosis, or filtration

permeability

the ease with which molecules cross biological membranes

water potential

a measure of the tendency of water molecules to move from one area to another measured in kilopascals (kPa)