The Endomembrane System

Question 1

vesicles

Answer 1

small-membrane enclosed sacs that transport substances within a cell or from ther interior to the exterior of the cell; form by budding off an organelle, taking piece of membrane and internal contents of the organelle to refuse with another organelle or plasma membrane

Question 2

endomembrane system

Answer 2

a cellular system that includes the nuclear envelope, the ER, the golgi apparatus, lysomes, the plasma membrane, and the vesicles that move between them

Question 3

exocytosis

Answer 3

vesicles fusing with the plasma membrane, releasing contents into the outside of the cell

Question 4

endocytosis

Answer 4

capturing substance from outside the cell by endgulfing it with cell membrane to bring it into the cell

Question 5

nuclear envelope

Answer 5

boundary of the nucleus

Question 6

nuclear pore

Answer 6

large protein complexes that allow the movement of molecules into and out of the nucleus

Question 7

ribosomes

Answer 7

the site of protein synthesis; amino acids assembled into polypeptide chains through information in teh mRNA

Question 8

endoplasmic reticulum ER

Answer 8

organelle bounded by a single membrane; continuout with the outer membrane of the nuclear envelope; prodeces and transports proteins and lipids used both inside and outside of the cell

Question 9

lumen

Answer 9

interior of the endoplasmic reticulum ER

Question 10

rough endoplasmic reticulum RER

Answer 10

the part of the ER studded with ribosomes; synthesizes transmembrane proteins, proteins that end up in the interior of organelles, and proteins destined for secretion

Question 11

smooth endoplasmic reticulum SER

Answer 11

the part of the ER without ribosomes; site of fatty acid and phospholipid biosynthesis

Question 12

golgi apparatus

Answer 12

ER → golgi apparatus → rest of the cell; modifies proteins and lipids produed by the ER; sorting station as proteins and lipids move to their final destination; site of synthesis of cell carbohydrates

Question 13

cisternae

Answer 13

series of flattened membrane sacs that make up the golgi appartus

Question 14

glycocylation

Answer 14

chemical modification in the golgi appartus in which sugars are covalently linked to lipids or specific amino acids of proteins to form glycoproteins

Question 15

glycoproteins

Answer 15

important components of eukaryotic cell surface; sugars attached to proteins protect it from enzyme digestion by blocking acess to peptide chain → forms flexible and protective coat over the plasma membrane

Question 16

lysome

Answer 16

specialized vesicles derrived from the golgi apparatus; degrades damaged and unneeded macromoleucles; pH ~ 5; selectively permeable

Question 17

protein sorting

Answer 17

process by which proteins end up where they need to be to perform their function

Question 18

signal sequence

Answer 18

proteins produec on free ribosomes have amino acid sequences → allowing them to be recognized and sorted; no signal sequence → remain in the cytosol; proteins produced on the RER → end up on the lumen of the endomembrane system, secreted out of the cell, or as transmembrane proteins

Question 19

nuclear localization signals

Answer 19

nuclear signal sequences enebale proteins to move through pores in the nuclear envelope

Question 20

signal-recognition particle SRP

Answer 20

RNA-protein complex recognizes a sequence as a free ribosome translates a protein in the cytosol; binds to signal sequence and the free ribosome → pauses translation → SRP binds with the receptor on the RER → ribosome becomes associated with RER → SRP receptor brings ribosome to channel in membrane of RER → SRP dissociates and translation continues allowing for growth of the polypeptride chain to be threaded through the channell

Question 21

signal-anchor sequence

Answer 21

proteins destined for cell membranes contain SAS