Chapter 5 Flashcards
(23 cards)
Selective permeability
Amphipathic
Having both a hydrophilic region and hydrophobic region. Ex. A phospholipid is an example of a Amphipathic molecule.
Fluid Mosaic Model
The currently accepted model of cell membrane structure, with envisions the membrane as a mosaic of protein molecules drifting laterally in a fluid bilayer of phospholipids.
Integral proteins
A transmembrane protein with hydrophobic regions that extend into and often completely span the hydrophobic interior of the membrane and with hydrophilic region in contact with the aqueous solution on one or both sides of membrane (or lining the channel in the case of a channel protein).
Peripheral proeteins
A protein loosely bound to the surface of a membrane or to part of an integral protein and not embedded in the lipid bilayer.
Transport proteins
A transmembrane protein that helps a certain substance or class of closely related substances to cross the membrane.
Channel proteins
A type of transport protein, Function by having a hydrophilic channel that certain molecules or atomic ions use as a tunnel through the membrane.
Carrier proteins
A type of transport protein, hold onto their passengers and change shape in a way that shuttles them across the membrane.
Aquaporins
A channel protein in the plasma membrane of a plant, animal, or microorganism cell that specifically facilitates osmosis, the diffusion of free water across the membrane.
Diffusion
A result of thermal energy, The radón thermal motion of particles of liquids, gases or solids. In the presence of a concentration or electrochemical gradient, diffusion results in the net movement of a substance from a region where it is more concentrated to a region where it is less concentrated.
Osmosis
The diffusion of free water molecules across a selectively permeable membrane.
Concentration gradient
A region along chic the density of a chemical substance increases or decreases.
Passive Transport
The diffusion of a substance across a biological membrane with no expenditure of energy.
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.
Active Transport
The movement of a substance across a cell membrane against its concentration or electrochemical gradient, mediated by specific transport proteins and requiring an expenditure of energy.
Tonicity
The ability of a solution surrounding a cell to cause that cell to gain or lose water.
Membrane potential
The difference in electrical charge (voltage) across a cell’s plasma membrane due to the differential distribution of ion. Membrane potential affects the activity of excitable cell and the transmembrane movement of all charged substances.
Electrogenic pump
An active transport protein that generate voltage across a membrane while pumping ions.
Cotransport
The coupling of the downhill diffusion of one substance to the “uphill” transport of another against its own concentration gradient.
Exocytosis
The cellular secretion of biological molecules by the fusion of vesicles containing them with the plasma membrane.
Endocytosis
Cellular uptake of biological molecules a particulate matter via formation of vesicles from the plasma membrane.
Three types:
phagocytosis (cellular eating)
Pinocytosis (Cellular drinking)
Receptor mediated endocytosis.
What is Isotonic, Hypertonic, and Hypotonic?
Isotonic: means same, referring to a solution that, when surrounding a cell, causes no net movement of water into or out of the cell. Water diffuses at the same rate in both directions.
Hypertonic: means more, referring to a solution that, when surrounding a cell, will cause the cells to lose water. Cell will die, reason foe why slaty lakes can kill animals.
Hypotonic: means less, referring to a solution that, when surrounding a cell, will cause the cell to take up water. Water will enter faster than it leaves and cell will overfill and burst.
The permeability of the lipid bilayer.
- non polar molecule like hydrocarbons like CO2 and O2 are hydrophobic like lipids and can cross it easily without aid of membrane proteins. Polar molecule can pass slowly like glucose and other sugars. water also does not cross rapidly.
