TRANSPORT MECHANISMS Flashcards
(36 cards)
______
- random molecular movement of substances molecule by molecule, either through intermolecular spaces in the membrane or in combination with a carrier protein
Diffusion
______
- utilizes energy of the normal kinetic motion of matter
Diffusion
______
- movement of ions or other substances across the membrane in combination with a carrier protein
Active transport
______
- the carrier protein causes the substance to move against an energy gradient (low-concentration to a high concentration state)
Active Transport
______
- requires an additional source of energy besides kinetic energy.
Active transport
Types of Diffusion:
Simple Diffusion
Facilitated Diffusion
______ diffusion
- kinetic movement of molecules or ions occurs through a membrane opening or through intermolecular spaces without interaction with carrier proteins in the membrane
Simple
Simple diffusion
- rate of diffusion is determined by:
• amount of substance available
• velocity of kinetic motion
• number & sizes of openings in the membrane through which the molecules or ions can move
______ diffusion can occur
• through the interstices of the lipid bilayer if the diffusing substance is lipid soluble
Simple
______ diffusion can occur
• through watery channels that penetrate all the way through some of the large transport proteins
Simple
______ diffusion
• requires interaction of a carrier protein that aids passage of molecules or ions through the membrane by binding chemically with them and shuttling them through the membrane
Facilitated
______ diffusion
• “carrier mediated diffusion”
Facilitated
______ diffusion
• a substance transported in this manner diffuses through the membrane with the help of a specific carrier protein
Facilitated
______ diffusion
• the carrier facilitates diffusion of the substance to the other side
Facilitated
______ of Substances Through Membranes
• a cell membrane moves molecules or ions uphill against a concentration gradient (or uphill against an electrical or pressure gradient)
Active Transport
______ of Substances Through Membranes
• sodium, potassium, calcium, iron, hydrogen, chloride, iodide, and urate ions, several different sugars, and most of the amino acids.
Active Transport
Active Transport
types according to the source of the energy used to facilitate the transport:
Primary active transport
Secondary active transport
______ active transport
• energy is derived directly from the breakdown of adenosine triphosphate (ATP) or some other high-energy phosphate compound
Primary
______ active transport
• energy is derived secondarily from energy that has been stored in the form of ionic concentration differences of secondary molecular or ionic substances between the two sides of a cell membrane, created originally by primary active transport
Secondary
______
• transport depends on carrier proteins that penetrate through the cell membrane
Active Transport
______
• the carrier protein functions differently from the carrier in facilitated diffusion because it is capable of imparting energy to the transported substance to move it against the electrochemical gradient
Active Transport
Primary active transport
______ Pump
• transports Na ions out of Cells and K ions into cells
Sodium-Potassium
Primary active transport
______ pump
• pumps sodium ions outward through the cell membrane of all cells and pumps potassium ions from the outside to the inside
Na+-K+
Primary active transport
______ Pump
• responsible for maintaining the sodium and potassium concentration differences across the cell membrane and establishing a negative electrical voltage inside the cells.
Sodium-Potassium