Topic 4: Cell Membranes and Transport Flashcards
Active Transport
the movement of molecules or ions through transport proteins (carrier and channel protein) across a cell membrane, against the concentration gradient, using energy from ATP
Bulk Transport
the movement across the membrane of a large quantity of materials which are taken in or out of the cell by vesicles. this process require energy.
Two type
endocytosis (phagocytosis and pinocytosis)
exocytosis
Carrier Protein
a type of membrane protein which changes shape to allow passage into or out of the cell of specific ion or molecules by facilitated diffusion or active transport
Cell Adhesion
the process which cells join together to form tissues
Cell Marker
some glycoproteins and glycolipids called antigen that give cell its identity and enable cell of similar type to group together to form the tissue
Cell Signalling
the molecular mechanism by which cells detect and respond to external stimuli, including communication between cells. carbohydrate chains or membrane protein act as the receptor
Cell Surface Antigen
a protein molecule used for cell recognition
Cell Surface Receptor
carbohydrate chains help glycolipids and glycoproteins to act as receptor molecules and identify markers for cell
Channel Protein
a membrane protein of fixed shape which has a water-filled pore through which selected hydrophilic ions or molecules can pass by facilitated diffusion
Cholesterol
a small, lipid-related molecule with a hydrophilic head and a hydrophobic tail which is an essential constitute of membranes, particularly in animal cells, conferring fluidity, flexibility and stability to the membrane
Diffusion
the net movement of molecules or ions from a region of higher concentration down a gradient, as a result of the random movements of particles
Endocytosis
the bulk movement of liquid (pinocytosis) or solid (phagocytoosis) into a cell, by the infolding of the cell surface membrane to form vesicles containing the substance; endocytosis is an active process requiring ATP
Exocytosis
the bulk movement of liquids or solids out of a cell, by the fusion of vesicles containing the substance with the cell surface membrane; exocytosis is an active process requiring ATP
Extrinsic Protein (Peripheral Protein)
extrinsic proteins are found on the surface of the membrane only. many are attached to intrinsic protein.
Facilitated Diffusion
the diffusion of a substance through transport protein in a cell membrane; the proteins provide hydrophilic areas that allow the molecules or ions to pass through the membrane which would otherwise be less permeable to them
Fluid Mosaic Model
the current accepted basic model of membrane structure, proposed by Singer and Nicolson in 1972, in which protein molecules are free to move about in a fluid bilayar of phospholipid molecules. the surface of membrane has a mosaic appearance as it is made up of smaller phosphate heads and larger proteins producing a mosaic effect
Gated Protein
part of the protein can move to open or close the membrane usually in response to a signal molecule
Glycocalyx
carbohydrate chain forming a sugary coating outside the cell. the chain forms hydrogen bonds with water outside the cell leading to greater stability.
Glycolipid
the phospholipid with carbohydrate chain (oligosaccharide) attached. these can act as receptor and recognition molecules
Glycoprotein
the protein with a carbohydrate chain (oligosaccharide) these can act as receptor and recognition molecules
G Protein
G Protein acts as a switch to bring about the release of a small molecule which diffuses through the cell relaying the message; the switch mechanism involves binding to GTP molecules
Incipient Plasmolysis
the point at which pressure potential has just reached zero and the plasmolysis is about to occur
Intrinsic Protein (Integral Protein)
the intrinsic protein may be found in one of the monolayers
Miscelle
stable sphere structure formed when phospholipid shaken up with water due to hydrophilic heads facing water and hydrophobic tails facing each other away from water
