Chapter 12 Flashcards
network of membrane-enclosed tubules and sacs (cisternae) - extends from nuclear membrane throughout cytoplasm.
ER
the secretory pathway
Rough ER → Golgi → secretory vesicles → cell exterior
Proteins synthesized on _______ stay in the cytosol or are transported to the nucleus and other organelles.
free ribosomes
Proteins synthesized on __________ are translocated directly into the ER through translocon.
membrane-bound ribosomes
Proteins move into the ER during their synthesis on membrane-bound ribosomes.
Cotranslational translocation
Proteins move into the ER after translation has been completed on free ribosomes.
Posttranslational translocation
cytosol is a _____ environment
reducing
the ER is a ______ environment
oxidizing
misfolded proteins removed from ER by
ERAD
If an excess of unfolded proteins accumulates, a signaling pathway called the ______ is activated.
unfolded protein response (UPR)
Eukaryotic membranes are made of 3 lipid types:
phospholipids, glycolipids, and cholesterol.
Most of phospholipids are synthesized on the _____ side of the ER membrane from water-soluble precursors (glycerol).
cytosol
passage of polar head groups through the membrane occurs by:
flippases
a targeting sequence at the carboxy terminus that directs retrieval back to the ER. (2 examples)
KDEL or KKXX
Most glycolipids and sphingomyelin are synthesized in the
Golgi.
receives molecules from the ERGIC
cis compartment
most modifications are done here
medial/trans compartments
the sorting and distribution center
trans-Golgi network
Transport vesicles with secretory proteins are coated with
coat proteins.
COPII-coated vesicles carry proteins from the
ER to the ERGIC
COPI-coated vesicles carry proteins to
their early compartments
Clathrin-coated carry proteins
in both directions
Interaction between transport vesicles and target membranes is mediated by
tethering factors
membrane-enclosed organelles that contain enzymes to break down all types of biological polymers
lysosomes
