ER, Golgi & Secretion Flashcards
What is the ER attached to?
nuclear envelope
What is the ER made of?
tubules and cisternae
What is the function of the ER
calcium store
What are located on the rough ER
ribosomes
What are translated on ribosomes?
transmembrane protein
What are the functions of the Rough ER?
Protein folding, storage, transport, detoxification
What does the rough ER store
proteins
What are the functions of the smooth ER?
phospholipid synthesis, steroid hormone production, synthesis & storage of glycerides and glycogen
Does the smooth ER store calcium?
YES
What do secretory granules contain (in acinar cells)?
digestive enzymes
What are secretory granules packed with digestive enzymes called?
zymogen granules
What causes vesicle fusion and enzyme release?
Ca2+ release
Is the release of calcium SUFFICIENT or NECESSARY to release digestive enzymes?
SUFFICIENT
What do zymogen granules fuse with?
plasma membrane
what happens when zymogen granules fuse with the plasma membrane?
digestive enzymes are released into the extracellular space
What is the sarcoplasmic reticulum?
ER in muscle cells
How is mobilisation of calcium important for the cell
muscle contraction - interaction of calcium & troponin expose myosin binding site
What is the Golgi formed from?
Several flattened cisternae
Which face of the Golgi is close to the ER
forming face - cis face
From which face of the Golgi do vesicles bud off from?
Maturing face - trans face
Meaning of juxta-nuclear
lies close to the nucleus
TRUE or FALSE - Golgi is juxtanuclear
TRUE
How do cisternae communicate with the ER and cell membrane
Using vesicles and tubules
What is the function/s of the Golgi
modify and package secretions, renewal & modification of PM, deliver material to organelles & PM
What are the three types of vesicle coats
COPI, COPII, and clathrin
What is the function of vesicle coats
aid formation of the vesicle
What do vesicle coats prevent
fusion
When are vesicle coats discarded?
before fusion with target
Where are t-SNAREs located
target membrane
Where are v-SNAREs located
vesicle membrane
What are the functions of SNAREs?
promote fusion, ensure each vesicle goes to the right place
What type of proteins are SNAREs
transmembrane proteins with large cytoplasmic domains
What happens when two SNAREs fuse?
form alpha helical bundles, membranes are close together
Where does fusion of SNAREs usually occur?
Nerve terminals for the docking of synaptic vesicles
What are the two models for progression through the golgi?
vesicular transport model, cisternal maturation
What are the three pathways controlling movement of vesicles?
Signal mediated diversion to lysosomes, constitutive secretory pathway, signal mediated diversion to secretory vesicles
What forms COPII vesicles
ER exit sites
What is the function of endocytosis
take up large components
What are lysosomes full of
hydrolytic enzymes
What is the function of lysosomes
hydrolyses and lipases
What is the function of pseudopods?
engulfing
What are pseudopods?
arms that come out of the cell
What is key for function of the endocytic pathway
gradient of pH
Describe phagocytosis
uptake of really large particles
What is frustrated phagocytosis
when associated macrophages dont fuse
What type of signalling does phagocytosis use
autonomous
Describe dictyostelium
express actin related protein
What is macropinocytosis
ruffling of the membrane
what is the function of macropinocytosis
trap and internalise material
Describe the receptors on LDLs
internalised
What can clathrin be easily purified from
bovine brain or placenta
Describe the structure of clathrin coated pits
hexagonal and pentagonal - polymerises to form lattice
Why is clathrin coat removed
to allow access to SNAREs
What is the function of dynamin
helps pinch off clathrin coated vesicles
What is the function of Rab proteins
define intracellular organelles and ensure they maintain their identity
What is the function of dictyostelium
take up yeast and mobilise actin cytoskeleton
