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Major types of coated vesicles "cargo" molecules
______ coated vesicles: move materials from the rough ER to the Golgi Apparatus
______ coated vesicles: move materials from the Golgi apparatus back to the rough ER and from trans Golgi cisterna back to the cis Golgi cisterna (ie retrograde transport)
_______-coated vesicles: move materials from the trans Golgi network (TGN) to endosomes, lysosomes, and plant vacuoles. Also move materials from the plasma membrane during endocytosis to endosomes.
Note. COP = coat protein
- COPII-coated vesicles
- COPI- coated vesicles (reverse to COPII)
- Clathrin-coated vesicles
Clarathin-coated vesicles are coated by ______ molecules. A ___ molecule had _ subunits. The structure it forms is called a _______
- 6 subunits
Intracellular vesicular traffic plays an essential role in
a) the ______ pathway
b) _______ - _____ pathway
- involves _______ vesicles. Some vesicles are ______ in shape and some vesicles are _______ or have an irregular shape
- endocytic pathway
- biosynthetic-secretory pathway
- transport vesicles
- spherical in shape and tubular in shape
Transporting "cargo" vesicles is from the Donor to the target via budding. ______ guide vessels to the target compartment. 2 major classes of "cargo" molecules. ____ and _____ molecules.
- microtubules guide vessels
- 2 major classes; lumenal and membrane molecules
where budding of cargo molecules takes place; most transport vesicles are formed from regions of a membrane ______ with special proteins. Budding produces ______ ______ that are covered on their ______ surface by the special proteins
- coated vesicles
- cystolic surface
Bud formation: ______ binds to the cargo receptor and _____ protein; forms a ______ basket on the cystolic surface of the membrane, a coated pit. The coated pit forms into a spherical 'cargo' molecule and then needs to pinch off the membrane. ______ and associated proteins use energy source _____ase to pinch off the cargo vessicle. Once the vessicle leaves the membrane into the cytosol, the _____ and ____ leave the vessicle resulting in a _____ transport vesicle in the cytosol.
- binds to cargo receptor and adaptor protein
- convex basket
- Dynamin (pinch of cargo ves.)
- Clathrin and adaptor proteins fall off
- naked transport vesicle
No mistakes in delivery ensured by transprt vesicles deliver their cargo only to the correct target compartment. This is ensured by the role of 2 classes of membrane protein.
1) _____ proteins ; direct vesicles to specific locations on the correct target membrane.
2) _____ proteins ; mediate vesicle fusion with the target membrane
____ proteins: direct vesicles to specidic locations on the correct target membrane. ____ proteins act as vesicle-targeting GTPases to help direct vesicles to a specific location on the correct target membrane.
____-____ in addition to the _-snare dock onto the target. The rab protein has affinity for the ____ effector tethering protein, docks and the _-snare interacts with the targets _-snare and fusion into the membrane begins.
- V-snare (donor)
- Rab-effector (target)
- V-snare(donor) interacts with the t-snare (target)
There are 2 major classes of SNAREs: (mediate vesicle fusion with the target membrane)
a) _-snares (located on vesicle membrane)
b)_-snares (located on target memrabes)
- These snares have affinity for each other and create the interaction required for fusion.
Rab proteins facilitate pairing of v-snares with t-snares to form a ____-_____ complex which locks the vesicle to the target membrane.
After the cargo vesicle docks onto the target membrane, membrane _____ occurs; involves _____ and other fusion proteins
- SNAREs and other fusion proteins
extra notes: membrane fusion also occurs in a number of other events including cytokinesis, cell fusion (eg sperm-egg fusion), endocytosis (eg phagocytosis and pinocytosis)
in order to re-use SNAREs, the trans-SNARE complex must be disassembled
These are the major functions of the ________.
1) major site for carbohydrate synthesis
2) receives proteins and lipids from the ER
3) glycosolation of proteins and lipids to form glycoproteins and glycolipids
4) modifications of the glycoproteins and glycolipids
5) sorting and packaging of the glycoproteins and the glycolipids into vesicles to one of 3 destinations: ______,______ , _______
- Golgi Apparatus
- 1)lysosomes 2) plasma membrane 3) extracellular fluid ( via secretory vesicles)
this structure receieves proteins and lipids from the ER.
The structure is the major site for carbohydrate synthesis. But also occurs to less of a degree in the _____
- Golgi apparatus
- lesser in the ER
The structure modifies glycoproteins and glycolipids. This structure also causes glycosolation of proteins and lipids
transport from the ER goes straight to the ______
In order for proteins to leave the ER, what is the conditions needed to leave? Where do they go?
- They proteins must be properly folded and if they are part of a subunit they must be properly assembled.
- The proteins are transferred to the golgi apparatus
______ proteins aid in the proper folding of proteins
_______-coated vesicles shed their coat to become uncoated vesicles. These vesicles the fuse with each other to form ___ ____ ____(____'s)
- COPII-coated vesicles
- vesicular tubular clusters (VTC's)
In addition to a motor protein, a _____ will guide the VTC's (fused naked vesicles) to the cis _____ network for fusion
- cis Golgi network
ER resident proteins are selected for retrieval because they have the appropriate sorting signals. These signals are called _____ ____ ____ (eg ______ sequence)
- ER retrieval signals
- KDEL sequence
In the Golgi Apparatus this action triggers budding of the COPI-coated vesicles
binding os soluble ER resident protein (containing KDEL sequence) to KDEL receptor
within the GA are flattened membranes-encloses sacs called _______
cisternae (usually consists of 4-6 cisternae)
where is the Golgi apparatus located?
near the nucleus
The golgi apparatus has 2 faces;
the ______ face that faces the VTC( _______) and the ____ face that faces the cell periphery ( the ____ region of the cell)
- cis face
- Vesicular tubular cluster
- trans face
- outer region
the cis face of the golgi apparatus is part of a special compartment called the ___ ___ ____( ___)
where as the trans face is part of a special compartment called the _______ (___)
- cis Golgi network (CGN)
- trans golgi network (TGN)
Proteins and lipids enter the GA through the _____ and exit through the _____ via vesicles that transport them to another compartment or the cell surface
The ____ ____ is the major site of carbohydrate synthesis. The seconday site of synthesis is the ___.
In the Golgi apparatus, modifications of glycoproteins and _________ occurs in the _______
These 2 models describe how molecules move through the GA.
- a) Vesicular transport model
- b) cisternal maturation model
Sorting of vesicles in the GA occurs in the _____ (________), and then are packaged into ____
- TGN (trans golgi network)
Ones processed and sorted in the TGN of the golgi apparatus, the vesicles are sent to 1 of 3 places.
- plasma membrane
lysosomes contain "______ enzymes" that are important for intracellular (within cell) digestion of these 2 compounds _____ and ____. The optimal cellular pH for optimal activity of these enzymes is __ in the lumen. This requirement has catagorized the enzyme as an _____ hydrolaze (side note: cytosol pH is ~ 7.2)
- pH~ 5.0
Lysomal membrane proteins and lipids are highly ______; protects them against being digested by lysosomal enzymes
How are lysomal proteins (glycoproteins) in the TGN selected for delivery to lysosomes?
lysosomal hydrolases (part of the molecule) have a signal patch that acts as a signal for the phosphorylation of mannose (M6P)
______ has M6P receptors that will bind to hydrolases of the ____ side of the membrane. Binding triggers _______
- TGN membrane
the lysosome membrane has ______ ______ that move the products of digestion into the cytosol
Transporting molecules into the cell from the plasma membrane is called _______. There are 2 methods to do this; includes _______ and ______.
Phagocytosis is a process of endocytosis where large particles are engulfed to form large vesicles called _______. This only occurs in specialized cells called _______ cells.
Pinocytosis on the contrary engulfs fluid ____ with ____ to form small vesicles called ______. This occurs in all eukaryotic cells.
- ECF with solutes
- pinocytic vessicles
In multicellular organisms, phagocytosis is primarily in _______ which includes these 2 cell types; __________ and ___________
Phagocytosis occurs when a ______ forms; triggered by binding of phagocytes surface receptors to specific substances on the surface of the targets cell. The pod is engulfs the target using microfilament ______
Pinocytosis occurs in almost all eukaryotic cells continously. The problem is it removes a bit of membrane. To conteract the removal of the membrane, _______ must add the _______ ______ of membrane to the cell surface at the _____ ____
- same amount
- same rate
The edocytic-exocytic cycle begins at _________ __; they are important for the ingestion of _____ ________ from the ECF . They ingested vesicles are formed from 'little cavities' called _____
- clathrin-coated pits
- specific macromolecules
True/false (if false make true): All pinocytic vesicles are clathrin-coated.
False. Some pinocytic vesicles are NOT clathrin-coated. Remember, these vesicles are formed from "little cavities" called caveolae
Name the process where clathrin-coated pits ingest specific macromolecules from the ECF.
receptor-mediated endocytosis (eg. uptake of cholesterol into animal cells)
Cholesterol is transported in blood in 2 different forms. Name the most common form of cholesterol.
LDL's (low density lipoproteins)
Unlike mitochondria, chloroplasts have __ membranes.