golgi vesicles and traffic Flashcards
1
Q
HVC
A
- hijacks host lipid metabolism and remodels host membranes to envelope itself
- double membrane vesicles
2
Q
endomembrane system
A
- organelles are connected directly by membranes or indirectly by transfer of membrane segments
3
Q
nuclear envelope + endoplasmic reticulum
A
- lumen of perinuclear cisternae is in continuity with the RER lumen
- outer membrane is similar to the membrane of RER
- inner has a different composition
- 2 types of membrane invagination into nucleoplasm
- GFP lamin
4
Q
the endoplasmic reticulum
A
- extensive membrane network of cisternae and tubuli
- quantity of ER quickly varies upon cell activation
- smooth ER lacks ribosomes on surface: site for lipids (steroids) synthesis and detoxification
- RER: ribosomes stud the surface: site for protein synthesis: products transferred via vesicles
- ER in most eukaryotic cells sequesters Ca2+ from cytosol
5
Q
RER:how do ribosomes bind?
A
- ribosomes not a stable part: constantly being bound and released from the membrane
- ribosomes bind through a receptor called ribophorin when it begins synthesis a protein to be secreted
- protein glycosilation begins in the RER and is completed in golgi
- vesicles shuttle proteins between these two compartments
6
Q
RER hypertrophy and acinar cells
A
- a significant increase in its amount
- acinar cells of exocrine portion of pancreas are abundant in ER
- principal site of pancreatic juice production
- pancreatin and other digestive enzymes are produced in RER and stocked in secretory granules
7
Q
visualising the RER
A
- RER is basophilic
- HandE, Nissl stain, GFP labeled proteins, IF,
8
Q
smooth endoplasmic reticulum
A
- in mainly cells are scanty and often party smooth and partly rough
- prominent in cells that specialise in lipid metabolism (e.g. steroid hormone synthesis
- many other reaction occur in SER: Gierke’s disease
9
Q
hepatocytes and SER
A
- rich in SER
- principal site of production of lipoprotein particles
- SER contains enzymes that detoxify both lipid-soluble drugs and various harmful compounds produced by metabolism
10
Q
muscle cells and SER
A
- muscle fibers abundant is specialised SER: sarcoplasmic reticulum
- release and uptake of Ca2+
- Ca2+ storage in lumen is facilitated by high cc of Ca2+ binding proteins
11
Q
Von Gierke’s disease
A
- glycogen storage disease type 1
- accumulation of glycogen in cytoplasm
- clinical signs: inadequate blood glucose levels, enlargement of liver, damage to tissue from hyperuricemia, bleeding infections
- deficiency of glucose-6-phosphatase enzyme located of SER membrane impairs ability of liver to produce free glucose from glycogen
12
Q
free ribosomes
A
- in cytoplasm
- appear as 25 nm granules by TEM
- synthesise proteins that remain in cytosol
- form clusters called polyribosomes
13
Q
golgi apparatus localisation
A
-positioned near the centrosome based microtubule-organizing center
- subdivided into 3 functionally distinguished compartments
- CIS forming face: vesicles fusing facing RER : network of membranous tubules appearance
- cis cisterna, medial cisterna, trans cisterna
- Trans maturing face releasing vesicles
- two alternative models for flux through golgi complex
14
Q
golgi functions
A
- post-translatioal modifications and sorting of neo-synthesize proteins
- synthesis of polysaccharide molecules (proteoglycans, mucins) and lipids
- sorting and dispatching station for the products of RER
- most glycosylation reactions occur in golgi
- signal-mediated diversion to lysosomes
- signal-mediated diversion to secretory vesicles for regulated secretion
- constitutive secretion
- N-glycosilation starts w addition of an oligosaccharide to NH2 group of an asparagine side chain
15
Q
cells with a well-developed golgi
A
- secretory cells
- synthesizing large amount of membrane and membrane-associated proteins
16
Q
intracellular traffic
A
- multidirectional, based on vesicle trafficking
- endocytic and biosynthetic secretory pathways
- retrieval pathway: maintenance of selected components backflow
