ch 3- plasma membrane Flashcards
plasma membrane
the phospholipid bilayer and embedded proteins which separate the intracellular environment from the extracellular environment. Also known as cell membrane
intracellular
inside a cell
extra cellular
outside a cell
selective permeability
a property of cell membranes that ensures only specific substances pass across them. Also known as semipermeable
phospholipid
the main molecule of which membranes are composed. They have a phosphate head and two fatty acid tails
phospholipid bilayer
a double layer of amphiphilic molecules that forms the primary component of cell membranes
phosphate head
the hydrophilic subunit of a phospholipid and is negatively charged and polar
fatty acid tail
the hydrophobic lipid subunit of a phospholipid, no charge and non polar
hydrophilic
having a tendency to be attracted to and dissolve in water
polar
describes a molecule with both a positive end and negative end. These tend to be hydrophilic
hydrophobic
having a tendency to repel and be insoluble in water
non polar
describes a molecule without a clearly positive or negative end. These tend to
be hydrophobic
amphipathic
describes molecules with both hydrophilic and hydrophobic components.
Also known as amphiphilic
protein
a class of biomacromolecule made of amino acid monomers folded into a
3D shape, consisting of carbon, hydrogen, oxygen, nitrogen, and sometimes sulphur
carbohydrate
a class of biomacromolecule made from monosaccharide monomers consisting of carbon, hydrogen, and oxygen. Also known as saccharides or sugars
cholesterol
a steroid-alcohol that regulates fluidity in plasma membranes
integral protein
a protein that is permanently secured to the plasma membrane
transmembrane protein
an integral protein that spans the entire plasma membrane
peripheral protein
a protein temporarily attached to the plasma membrane
cytoskeleton
the microscopic web of protein filaments in the cytoplasm. It provides structure and support, and transports products around the cell
glycolipid
a phospholipid bound to a carbohydrate
glycoprotein
a protein bound to a carbohydrate
function of proteins
transport, catalysis, communication and adhesion
function of carbs
cell-cell communication, signalling, recognition, adhesion
cholesterol
regulates fluidity of the membrane, higher temperature the cholesterol keeps them bound together and at lower temperature, it disrupts the fatty acid tails, stopping phospholipids from becoming a solid boundary
fluid mosaic model
the theory of how the plasma membrane is structured
saturated
a fatty acid chain with only single bonds between carbon atoms
unsaturated
a fatty acid chain with at least one double or triple bond between carbon atoms
cytosol
the aqueous fluid that surrounds the organelles inside a cell
passive transport
the movement of molecules through a semipermeable membrane and down the concentration gradient, without an input of energy
active transport
movement of molecules across a semipermeable membrane that requires energy
diffusion
the passive movement of molecules from areas of
high concentration to areas of low concentration (down the concentration gradient)
concentration gradient
the difference in solute concentration between two adjacent areas
kinetic energy
the energy a particle or body possesses due to motion
solute
a substance dissolved in the solvent
solvent
a liquid in which a solute is dissolved, forming a solution
facilitated diffusion
a type of passive transport where molecules move through a phospholipid bilayer with
the aid of a membrane protein
protein channel
a transmembrane protein pore in a phospholipid bilayer that selectively enables transport of large or polar molecules
carrier protein
a membrane protein that undergoes conformtional change to transport molecules across a membrane
conformational change
a change in the three-dimensional shape of macromolecules such as proteins
osmosis
the passive transport of a solvent (typically water) through a semipermeable membrane
from a region of low solute (high solvent) to a region of high solute (low solvent)
tonicity
a measure of the relative concentration of solutes on either side of a semipermeable membrane, described as hypertonic, hypotonic, or isotonic
hypertonic
describes a solution with a higher solute concentration when compared to another solution
isotonic
describes a solution with the same solute concentration as another solution
hypotonic
describes a solution with a lower solute concentration when compared to another solution
turgid
describes plant cells that are swollen and firm from water uptake
plasmolysed
describes plant cells with weak and sagging plasma membranes from water loss
lyse
to cause a cell plasma membrane to burst or break
protein mediated active transport
a type of active transport which involves using membrane proteins to move molecules across a membrane against their concentration gradient. Also known as active transport
bulk transport
a type of active transport that uses vesicles to move large molecules or groups of molecules into or out of the cell. Also known as cytosis
protein pump
a polypeptide that transports molecules across a membrane against its concentration gradient with the aid of ATP
adenosine triphosphate
a high energy molecule that, when broken down, provides energy for cellular processes
carrier protein
a membrane- based protein that undergoes conformational change to transport molecules across a membrane
conformational change
a change in the three-dimensional shape of macromolecules such
as proteins
exocytosis
a type of bulk transport that moves large substances out of the cell
osmosis
the passive transport of a solvent (typically water) through a semipermeable membrane
from a region of low solute (high solvent) to a region of high solute (low solvent)
vesicle
a small membrane-bound sac that transports or stores substances within a cell
endocytosis
a type of bulk transport that moves large substances into the cell
secretory products
the substances inside a vesicle that are being transported out of the cell
phagocytosis
endocytosis of solid
material or food particles
pinocytosis
endocytosis of liquid or dissolved substances
