The Endimembrane System And Membrane Traficking Flashcards
Ribosomes attached to mRNA are called
Polysemy’s or polyribosomes
Polyribosomes are found in either the
Cytosol
Rough ER
The function of the rough ER includes
Protein production
Protein modification
The rough ER Consists of parallel stacks of membrane called
Cristae
Proteins are packed in______which from the rough ER to the______ for further maturation
Vesicles; golgi complex
After the golgi complex. proteins are packaged into vesicles and sent to
The outside of the cell
Insertion in the plasma membrane or organelles membrane
Lumen of the ER and the golgi
Lysosomal matrix
The pathway from the golgi to other desired locations is called the
Secretory pathway
Proteins of the cytosol need a targeting signal to reach their destination . T/F
False
Only proteins bound to organelles need a targeting sequence
SRP is the______for the ER signal sequence
Receptor
What happens when SRP binds the ER signal sequence
Translation is paused
Membrane proteins are always translated on
ER bound polyribosomes
Membrane spanning domains are primarily______and located on the polypeptide chain
Hydrophobic
When Membrane spanning domains enter the protein _______, this allow the insertion of membrane proteins into the membrane
Translocon
Protein modifications in the ER Include
Formation of Disulfide bonds
Cleavage of ER signal sequences
N-linked glycosylation
Protein folding
The formation of Disulfide bonds aids in
Protein folding
Signal peptidase is is responsible for
Cleaving SRP and degrading them
In N-linked glycosylation, polysaccharides attach to_______residues on the polypeptide chain
Asparagine: N
Protein folding is aided by chaperones
of the ER lumen called
BiP (binding protein)
Protein fold up incorrectly in the ER are
actively retained and not allowed to exit
T/F
True
Misfolded proteins are dislocated back through the ER translocator channel to be degraded in the cytoplasm by
Proteasomes
Misfolded proteins are marked with_____
Ubiquitin
Cystic fibrosis is occurs when a deletion mutation in the
CFTR gene
Normal CFTR protein is responsible for
Transporting chloride ions into and out of the cell
Mutated CFTR is marked with_______for degradation
Ubiquitin
Abnormal epithelial transport of Cl- affects the
Viscosity of the mucous covering the epithelial cells
The defective Cl- channel protein in the bronchial
epithelium causes decreased Cl- secretion and
Increased sodium ions and water reabsorption
Smooth ER differs in the rough ER in that
Smooth ER does not contain any bound ribosomes
smooth ER appears as_________ in the TEM section
Tubules and vesicles
The function of the smooth ER include
Biosynthesis of steroid hormones and membrane lipids
Breakdown of toxins and drugs
Sequestration of Ca++ in striated muscles
The golgi consists of 3 regions. What are they
Cis
Medial
Trans
Cis golgi recieves________ from the ER
Protein loaded vesicles
Trans golgi is the_______for proteins to their matured destinations
Sorting mechanism
Protein modification in the golgi includes
Trimming and addition of polysaccharides
O-linked glycosylation
O-liked glycosylation includes the attachment of polysaccharides to hydroxyl groups of
Lipid and serine OR threonine
Branched carbohydrates in the outer leaflet of the plasma membrane are called
Glycocalyx
Cargo is sorted at the _____golgi and is secreted into 3 types of vesicles. They include;
Trans;
Lysosomes
Regulated
Constitutive
Clathrate coated vesicles form at the______ and during_____
Trans golgi
Receptor mediated endocytosis
Clathrate coated vesicles formation is initiated by which ligand
LDL
_________is an enzyme that pinches off and suspends clathrin coated vesicles free into the cytoplasm
Dynamin
Vesicles returning from the golgi to the rough ER are coated with
COP I
vesicles moving from the rough ER to cis golgi are coated with
COP II
V SNARES (SNAP receptors) are present on
Vesicles
T-SNARES (SNAP receptors) are present on
Target membranes
Botox works by degrading specific______ which prevents fusion of exocytic vesicles containing______with the plasma membrane
SNARES; acetylcholine
Botox works by preventing
Muscle contraction
RABS are a_______
GTP binding protein
Docking protein
What does RABS do
It’s a docking enzyme. It binds a tethering protein and assists in the contact between a vesicles and a membrane
Lysosomes are only active under
Acidic pH
What kind of enzymes are lysosomal enzymes
Hydrolases
Synthesis of lysosomal enzymes occur in the
Rough ER
Lysosomal hydrolases receive which signal as they travel through the rough ER
M6P signal
Membranes of the trans golgi contain_______which bind the lysosomal hydrolases and cluster them into clathrin coated vesicles
M6P receptors
Autophagosomes Is a mechanism in which the cell_______£which is then directed to the
Degrades it’s own organelles; lysosome
3 types of endocytosis include
Phagocytosis
Pinocytosis
Receptor mediated endocytosis
Phagocytosis is the ingestion of
Large particles
Pinocytosis is the ingestion of
Fluids
Large particles to be eaten by phagocytes are coated with antibodies saying ‘eat me’. This is called
Opsonization
In exocytosis, in the regulated secretory pathway, cargo loaded vesicles are only released when
When the cell receives a proper signal such as insulin
Rise in cytosolic Ca ++ is the signal for
fusion of the vesicle with the plasm membrane
Constitutive secretory pathway vesicles travel to the plasma membrane and fuse with it immediately and require no signal. T/F
True
