Cell Structure and Function: Protein Sorting Flashcards
protein sorting
process by which a cell transports and directs proteins to specific organelles or secretion outside the cell
(ER) signal sequence or signal peptide
short amino acid sequence which targets nascent proteins to the endoplasmic reticulum and secretion pathway
fluid mosaic model of membrane structure
a model that describes the phospholipid bilayer as fluid and proposes that integral membrane proteins float freely in the lipid bilayer
cell secretion
release of proteins or other cellular products into the extracellular space
exocytosis
process by which secretory vesicles fuse with and become part of the plasma membrane, releasing vesicular contents outside the cell
endocytosis
process by which vesicles are internalized from the plasma membrane; often used to absorb or ingest molecular contents into the cell
integral membrane protein
protein that is permanently embedded in the cell membrane
transmembrane protein
integral membrane protein that spans the entire width of a cell membrane
osmosis
diffusion of water across a selectively permeable membrane due to solute differences on either side of the membrane
isotonic solutions
solutions separated by a membrane and containing an equal concentration of non-permeating solutes
hypotonic solution
solution with a lower concentration of non-permeating solutes than that of the solution on the other side of a membrane
hypertonic solution
solution with a higher concentration of non-permeating solutes than that of the solution on the other side of a membrane
facilitated diffusion (passive transport)
movement of molecules across a membrane via transport proteins without energy from ATP hydrolysis
active transport
movement of molecules across a membrane, typically against a concentration gradient, by transport proteins that require energy from ATP hydrolysis; this energy requirement can be direct (primary active transport) or indirect (secondary active transport)
electrochemical gradient
combined electrical and chemical (diffusion) forces acting on an ion between two sides of a cell membrane