Chapters 5 And 6 Flashcards
Fluid Mosaic Model
Proteins in the membrane can move along the plane of the membrane, producing an ever-changing configuration.
Cholesterol
Molecules are a fluidity “buffer,” keeping hydrocarbon chains fluid at low temperatures and stabilizing them at high temperatures.
Integral membrane proteins
Amphiphathic proteins family bound to the membrane.
Transmembrane proteins
Integral proteins that extend completely through the membrane.
Peripheral membrane proteins
Located on inner or outer surface of plasma membrane, bound to exposed regions of integral proteins.
Glycoproteins
Sugars are added to proteins to make glycoproteins
Passive transport
The movement of substances (as by diffusion and osmosis) across a cell membrane without the expedenture of energy.
Active transport
Movement of molecules against their gradient.
Signal transduction
Some receptors bind with signal molecules such as hormones and transmit information into the cell.
Intercellular junction
Cell adhesion proteins attach membranes of adjacent cells.
Selectively permeable
Allow some, but not all, substances to pass through them. A membrane may block a particular substance at one time and actively promote passage at another time. By regulating chemical traffic across its plasma membrane, a cell controls its volume and its internal molecular composition.
Transport proteins
Move ions, amino acids, sugars and other needed polar molecules through membranes.
Carrier proteins
a transport protein that is specific for an ion, molecule, or group of substances. Carrier proteins “carry” the ion or molecule across the membrane by changing shape after the binding of the ion or molecule. Carrier proteins are involved in passive and active transport.
Channel proteins
a type of transport protein, acts like a pore in the membrane that lets water molecules or small ions through quickly.
Diffusion
The movement of molecules so that they spread out into available space (down concentration gradient.)
Concentration gradient
The difference in the concentration of a substance between two areas. The bigger the difference, the steeper the concentration gradient and the faster the molecules of a substance will diffuse.
Osmosis
The diffusion of water across a membrane.
Potential energy
energy due to position, it is stored energy which can be used to do work. A gradient of the membrane is a form of potential energy. The stored energy of the concentration gradient is released when ions or molecules move from high to low concentration.
Facilitated diffusion
the passive movement of molecules across the cell membrane via the aid of a membrane protein.
Hypertonic
higher concentration of solute.
Hypotonic
Lower concentration of solute.
Isotonic
Equal concentration of solute.
Sodium-potassium pump
helps to maintain osmotic equilibrium and membrane potential in cells. The sodium and potassium move against the concentration gradients. The Na+ K+-ATPase pump maintains the gradient of a higher concentration of sodium extracellularly and a higher level of potassium intracellularly.
Membrane potential
Membrane potential is the difference in electric potential between the interior and the exterior of a biological cell.
Electrochemical gradient
The electrochemical gradient is a measure of the free energy available to carry out the useful work of transporting the molecule across the membrane.
Antiporter
a membrane protein that transports two molecules at the same time in the opposite direction.
Uniporter
A transport mechanism that drives a single compound or ion across a membrane, not coupled with transport of any other compound or ion.
Proton pump
a special kind of transporter that push hydrogen ions from areas of low concentration to areas with high concentration.
Symporter
an integral membrane protein that is involved in the transport of two different molecules across the cell membrane in the same direction
Cotransport
The linked, simultaneous transport one substance across a membrane, coupled with the simultaneous transport of another substance across the same membrane in the same direction.
Exocytosis
The secretion of large molecules within transport vesicles.
Endocytosis
Takes material in via vesicles that bud inward from the plasma membrane.
Phagocytosis
Ingesting large solid particles. “Cell eating.”
Pinocytosis
Taking in dissolved materials. “Cell drinking”
Plasmodesmata
microscopic cytoplasmic canal that passes through plant-cell walls and allows direct communication of molecules between adjacent plant cells.
Adhering junctions
cell-cell adhesion complexes that are continuously assembled and disassembled, allowing cells within a tissue to respond to forces, biochemical signals and structural changes in their microenvironment.
Tight junctions
An intercellular junction between epithelial cells in which the outer layers of the cell membranes fuse, reducing the ability of larger molecules and water to pass between the cells.
Gap junctions
aggregates of intercellular channels that permit direct cell–cell transfer of ions and small molecules
Cell signaling
Mechanisms by which cells communicate with one another.
Signal transmission
A cell releases signaling molecules (ligand). If target sells are not nearby, signal must be transported to them.
Ligand
something that binds with a biological molecule to form a complex and produce some effect.
Target cell
a cell that is acted on selectively by a specific agent (as a virus, drug, or hormone).
Reception
Glycoprotein receptors that bind with specific signaling molecules.
Receptor
A molecule inside or on the surface of a cell that binds to a specific substance and causes a specific effect in the cell
Signal transduction
The process by which a cell responds to substances outside the cell through signaling molecules found on the surface of and inside the cell.
Response
A signal is converted into a response to alter some cell process.
Neurotransmitter
The body’s chemical messengers. They are the molecules used by the nervous system to transmit messages between neurons, or from neurons to muscles.
Hormone
chemical substances that act like messenger molecules in the body. After being made in one part of the body, they travel to other parts of the body where they help control how cells and organs do their work.
Endocrine gland
An organ that makes hormones that are released directly into the blood and travel to tissues and organs all over the body. Endocrine glands help control many body functions, including growth and development, metabolism, and fertility.
Local regulators
chemical signals that travel over short distances by diffusion. • Local regulators help regulate blood pressure, nervous system function, and reproduction.
Ion channel
located within the membrane of all excitable cells, and of many intracellular organelles. They are often described as narrow, water-filled tunnels that allow only ions of a certain size and/or charge to pass through.
Protein kinases
any of a class of enzymes that catalyze the transfer of a phosphate group from ATP to one or more amino acids in the side chain of a protein resulting in a conformational change affecting protein function.
