inside the cell part 4

• *used to study the structure & function of organelles & cells
• it allowed researchers to isolate particular cel components and analyze their chemical composition
• splits cells into parts to analyze

• *found in nuclear envelope
• these 'gate-like structures' extend through both inner and outer nuclear membranes
• connect the inside of the nucleus w/ the cytosol
• proven that the pores are like doors to the nucleus

• *found in nuclear envelope
• protein molecules form an elaborate structure called nuclear pore complex
• proven that nuclear pore complex is the only gate between the cytoplasm and the nucleus and only certain molecs can get in and out

most are manufactured in the nucleolus where they bind to proteins to form ribosomes which are exported to the cytoplasm

molecules called 'messengers' carry information required to manufacture proteins out to the cytoplasm where protein synthesis takes place

• parasites that use the cell's machinery to make copies of themselves
• when a virus infects a cell, certain of its proteins enter the nucleus

proteins are synthesized by ribosomes in the cytosol but are headed for the nucleus contain a "zip code" - a molecular address tag that marks them for transport through the nuclear pore complex

• 'zip code'
• 17-amino-acids-long
• a molecular address tag that marks proteins for transport through the nuclear pore complex(destined for the nucleus)

• composed of smooth and rough ER and the golgi apparatus
• primary system for protein and lipid synthesis

• proposes that proteins intended for secretion from the cell are synthesized and processed in a highly prescribed set of steps(everything has a procedure)
• proteins are packaged into vesicles when they move from RER to Golgi apparatus & from Golgi apparatus to cell surface

RER-Golgi apparatus-cell surface

• predicts that proteins bound for the endomembrane system have a "zip code" that directs the growing polypeptide to the ER
• similar to the NLS(nuclear localization signal)
• this 'zip code' is a 20-amino-acid-long ER signal sequence
• the ER signal sequence binds to a signal recognition particle (SRP) that binds to a receptor in the ER membrane

• "sugar-together"
• carbohydrates are attached to the protein
• resulting in a glycoprotein

• "outside-cell-act"
• process where some proteins are sent to the cell surface in vesicles that fuse with the plasma membrane, fuse w/ plasma membrane to release contents to exterior of the cell
• this is how digestive enzymes are delivered...why we can digest our food