BIOL 1090 Lecture Notes - Lecture 5: Signal Peptide, Glycosylation, Lipid Bilayer
Document Summary
Endosymboint theory: certain organelles of the eukaryotic cell have evolved from smaller prokaryotic cells that have taken up residence within the cytoplasm of a larger host cell. Dynamic system in which materials are shuttled back and forth about the cell. Extensive network of membranous canals (transport vesicles) and stacks of cisternae. Constitutive: materials transported in secretory vesicles & continuously discharged into extracellular space. Regulated: materials stored as membrane-bound packages that are discharged only in response to a specific stimulus. Materials move from outer cell surface to cytoplasmic organelles. Synthesized protein specific destination in cell. Sense of polarity/directionality within cell is essential. Sorting signals encoded in amino acid codes. Membrane-bound vesicles with contents flow and fuse. Used to connect site of synthesis, transport routes, and final target of proteins. Uses radioactive isotopes (r) & tissue sections covered in layer of photographic emulsion. Pulse: short incubation with r, labeled aa"s incorporated into protein.