week 6 Flashcards
Plasma Membrane
bio membrane that separates the internal contents of a cell from its external environment
Leaflet
Half a phospholipid bilayer that faces a different region in the cell (asymmetrical)
glycolysation
process of covalently attaching a carbohydrate to a protein or lipid
glycolipid
a lipid with attached carbohydrate
Glycoprotein
a protein with attached carbohydrate
cell coat or glycocalyx
carbohydrate-rich zone on the cell surface that protects from mechanical and physical damage
simple diffusion
without the aid of a transport protein (directly through the channel)
facilitated diffusion
diffusion across a membrane with the aid of transport proteins (energetically favorable)
passive transport
simple and facilitated diffusion
active transport
low to high conc.
NOT energetically favorable
spends ATP to move molecule against concentration gradient
hydrophobicity
a key determinant of how readily a small molecule can diffuse across the bilayer
osmosis
movement of water across membranes in response to solute concentration gradients
isotonic
solute concentration outside the cell is equal to the inside of the cell
hypertonic
the solute concentration outside the cell is higher to the inside of the cell
hypotonic
the solute outside the cell is less to the inside of the cell (think ‘HYPE’ for water)
turgor pressure (opposite of osmosis)
generates osmotic pressure that stops the net flow of water in hypotonic environment
transport proteins
channels, transporters
channels
most are gated
transmembrane proteins that form a passageway for the facilitated diffusion of ions or molecules across the membrane
transporters
membrane proteins that bind to a solute and undergo a conformational change that moves to the other side of the membrane
gating mechanisms
ligand-gated channels
voltage-gated channels
mechanosensitive channels
non covalent binding of intracellular regulatory proteins or covalent attachment of a small molecule can also trigger opening
active transport
movement of a solute across a membrane against its gradient, from a region of low concentration to higher concentration
endocytosis
plasma membrane folds inward to form a vesicle that brings substances into the cell (end-enter)
exocytosis
packages material inside the cell into vesicles that will be extracted into the extracellular environment (transport to plasma membrane and out of cell)
