Biology Chapter 5: Membranes
Terms in this set (29)
Plasma membrane layers composed of phospholipid molecules arranged with polar heads facing the outside and nonpolar tails facing the inside. Globular proteins are inserted into it.
Fluid Mosaic Model
Mosaic of proteins floats in or on the fluid lipid bilayer like boats on a pond.
Proteins embedded in the membrane that serve as transporters channels, enzymes, signal transducers, etc.
Interior Protein Network
membranes are structurally supported by intracellular proteins that reinforce the membrane's shape
Cell surface markers
Glycoproteins and glycolipids
Extensive nonpolar regions in a transmembrane protein create a ______. A cyclinder of Beta-sheets in the secondary structure is called a Beta-Barrel. The interior is polar and allows polar molecules and water to pass through.
The movement of molecules through a membrane that DOESN'T require energy and molecules move in response to a concentration gradient.
Movement of molecules from a high concentration to a low concentration. This continues until concentration is equal in all regions.
Molecules that can't cross the membrane easily will move through proteins. Moves from higher to lower concentration. Uses Channel Proteins or Carrier Proteins.
Allows passage of Ions. Gated channels open and close in response to stimuli. 3 conditions determine direction:
-Concentration on either side of membrane
-Voltage differences across membrane
-Gated Channels: channel open or closed
Helps transport ions and other solutes, such as sugars and amino acids. Requires a concentration difference across the membrane. Carrier proteins bind to the molecule they're transporting in order to transport them across the membrane. Carriers can become saturated.
Carrier proteins are limited by the number of transporters. This is the maximum rate of transport.
net diffusion of water across a membrane towards a higher solute concentration.
the aqueous solution inside the plasma membrane of a cell.
Force needed to stop osmotic flow. If membrane is strong, cell reaches counterbalance with osmotic pressure driving water in and hydrostatic pressure driving water out.
Transport requiring energy. ATP is used directly or indirectly. Moves substances against concentration gradient. Uses carrier proteins.
Carrier protein that moves one molecule at a time.
Carrier proteins that move two molecules at a time in the same direction.
Carrier proteins that move two molecules at a time in opposite directions.
Water is ejected through contractile vacuoles to maintain osmotic balance
Cells keep isotonic with their environment in order to maintain osmotic balance.
Plant cells use this to push the plasma membrane against the cell wall and keep the cell rigid.
An antiporter moves 3 Na+ out of the cell and 2 K+ into the cell. ATP energy changes the affinity of the carrier protein for either Na+ or K+ in order to keep the pump functioning.
Uses ATP indirectly. The energy released when a molecule moves by diffusion fuels the active transport of another molecule. Glucose-Na+ symporter captures the energy from Na+ diffusion to move glucose across the concentration gradient.
Movement of substances into the cell.
Cell takes in particulate matter.
Cell takes in fluid.
Receptor mediated endocytosis
Specific molecules are taken in after binding to a receptor.
Movement of substances out of a cell. Requires energy. Used in plants to export cell wall material. Used in animals to secrete hormones, neurotransmitters, digestive enzymes, etc.