CH 4 SG Flashcards
Channel proteins
Protein that forms a channel to allow a particular molecule or ion to cross the plasma membrane
Diffusion
is the movement of molecules to
spread out evenly into the available space (from high to low concentration)
How do transport proteins facilitate diffusion?
providing a specific pathway through the cell membrane for certain molecules to move across, allowing them to bypass the hydrophobic interior of the membrane and diffuse down their concentration gradient
Hypertonic solutions
(Planet / animal cells shrink) Solutions that cause cells to shrink or shrivel due to loss of water
How are active carrier proteins used to transport molecules against a concentration gradient?
(Active transport…. “uphill”) (examples include Na/K pump, proton pump) using energy from ATP to change their shape, allowing them to bind to specific molecules on one side of the cell membrane, move them across the membrane, and release them on the other side
Facilitated transport
Passive transfer of a substance into or out of a cell along a concentration gradient by a process that requires a protein carrier
Exocytosis
(a vesicle fuses w/ the plasma membrane as secretion occurs) a fundamental process in eukaryotic cells that involves the release of large molecules from the cytoplasm to the cell’s exterior
Selectively permeable
The plasma membrane can carry out this function / meaning that’s certain substances can move across the membrane, while others cannot
Extracellular matrix (ECM)
Protective meshwork of proteins in polysaccharides in close association with the cell that produced them
How is diffusion affected by concentration gradients?
the steeper the concentration gradient (greater difference in concentration between two areas), the faster the rate of diffusion will be
hypotonic solutions
Solutions that cause cells to swell or even burst due to an intake of water (solution with a lower concentration of solute/higher concentration of water than inside the cell) (animal cells swell/lyse)(planet/turgid)
isotonic solutions
Refers to the osmotic pressure or tension of the solution (the solute concentration, and the water concentration both inside and outside the cell are equal) (no net gain or loss of water)
Three main types of endocytosis:
-pinocytosis
-receptor-mediated endocytosis
-phagocytosis
Endocytosis
(Cells taking substances by vesicle formation) plasma membrane invaginates to envelop the substance, and then the membrane pinches off to form and intracellular vesicle
Carrier proteins
Protein in the plasma membrane that combines with and transports a molecule or ion across the plasma membrane
Cell recognition proteins
(glycoproteins) these proteins help the body recognize invasions by pathogens for immune reaction to occur
Receptor proteins
Protein located in the plasma membrane or within the cell; binds to a substance that alters some metabolic aspect of the cell
Enzymatic proteins
Protein that catalyzes a specific reaction; may be found in the plasma membrane or the cytoplasm of the cell
facilitated diffusion
(this assisted transport is a type of passive transport) the passage of molecules (glucose/amino acids) across the plasma membrane even though they are not lipid-soluble
Osmosis
The diffusion of water across a selectively permeable membrane due to concentration differences
Osmosis Pressure
Measure of the tendency of water to move across a selectively permeable membrane; visible as an increase in liquid on the side of the membrane with higher solute concentration.
(the greater the possible osmotic pressure, the more likely it is that water will diffuse in that direction)
Active transport
(Sodium-potassium pump/proton pump) molecules or ions move through the plasma membrane, accumulating either inside or outside the cell.
For example, iodine collects in the cells of the thyroid gland (toward higher concentration)
Adhesion junctions
Serve to mechanically attach adjacent cells
Tight junctions
Brings adjacent cells even closer the desmosomes they actually connect plasma membranes between adjacent cells together (zipper-like fastening)
Gap Junction
(Allow cells to communicate) it is formed when two identical plasma membrane channels join
Plasmodesmata
In plants, cytoplasmic connections in the cell wall that connect two
adjacent cells.
Aquaporins
are channel proteins that allow rapid
diffusion of water
Osmoregulation
The control of water balance (Vital to survival of organisms)
Sodium-potassium pump
(The pump uses energy from ATP to transport three sodium ions out of the cell and two potassium ions in/active transport)
A change in carrier shape after the attachment of a phosphate group and again after it’s detachment allows the carrier to combine alternately with sodium ions and potassium ions
Phagocytosis
cells engulf large substances, forming an intracellular vacuole (common in single celled organisms/amoebas)
Pinocytosis
Occurs when vesicles form around a liquid or around a very small particles (white blood cells/cells that line the kidney tubules)
Receptor–Mediated Endocytosis
A form of endocytosis that is quite specific because it uses a receptor protein shape so that a specific molecule (vitamin, peptide hormone, lipoprotein) combines to it
Passive Transport
(toward lower concentration) movement of substances across a cell membrane that does not require the cell to expend energy
