Cell structure Flashcards
What classes of phospholipids are on the cytosolic side of the membrane?
Amino phospholipids (ex. phosphatidyl-ethaloamine and phosphatidyl-serine)
What classes of phospholipids are on the extracellular side of the membrane?
Choline derived phospholipids (ex. phosphatidyl-choline and sphingo-myelin)
What kind of lipid is sphingolipid?
Glycolipid from the golgi.
This functions as protection in the gut?
Glycocalyx - many covalently attached sugar groups
Where are the following synthesized?
Phosphoglycerides
Sphingomyelin
Glycolipids
- ER
- Golgi from sphingosine
- Golgi from sphingosine
What is integrin?
It is a transmembrane protein that binds extracellularly to collagen or fibronectin as well as intracellularly to cytoskeleton (keratin)
Two integral membrane proteins in RBC plasma membrane?
Glycophorin and Band 3. Bind to cytoskeleton of actin and spectrin giving elastic properties.
Name protein for cell to cell adhesion?
cadherins
What determines if protein is translated into the ER membrane? What determines if it crosses the membrane?
Signal sequence of mRNA that recognizes SRP receptor in membrane. Protein translocator facilitates entry into membrane. The number and orientation of hydrophobic start/stop signals determines position in membrane.
What is the cellular pathology of cystic fibrosis?
It is caused by a faulty membrane protein (CFTR) that acts a chloride transporter. This transporter functions in formation of sweat, mucous, pancreatic digestive fluid, and other exocrine secretions.
Pathology of Duchenne muscular dystrophy?
It is caused by a mutation in dystrophin which is a protein linking an integral membrane complex with the actin cytoskeleton. There are 9 forms of muscular dystrophy but all are associated with loss of structural integrity at intracellular (actin) to extracellular (collagen) linkage.
What is the pathology of hereditary spherocytosis and what cells does it effect?
Dysfunction of mechanical support proteins in the RBCs. Ankyrin is covalently bonded to Band 3 integral membrane complex. Spectrin interlinks short actin protofilaments in the cytoskeleton normally.
Where is N-linked glycosylation and how?
Occurs in ER, modified in golgi. Linked to asparagine. N-linked makes up most of glycoproteins.
Where are O-linked glycoproteins made and what type does it produce.
Made in the golgi. Make proteoglycans.
Where are misfoled ER proteins degraded?
Degraded in cytosol. Detected in ER.
What do heat shock proteins do in the ER?
They are sensors for misfolding and respond by increasing transcription for chaperones, translocators, and proteasomes as well as decrease general protein synthesis.
Where is lipid synthesis in cell?
Primarily smooth ER (high in hepatocytes)
A cell that uses a lot of calcium likely has a lot of what organelle?
Endoplasmic reticulum.
What organelle is reponsible for detoxification carried out by p450 enzyme?
Smooth endoplasmic reticulum.
What is protein in cytosolic leaflet causing invaginations that give rise to uncoated vesicles?
Caveolae - usually goes to the golgi
What are the two proteins in coated vesicles?
Clathrin - Lattice protein associated with trans side of golgi (Lysosomes)
Coatamer (Cop I and II) - Associated with cis side of golgi Cop I - From golgi to ER or plasma membrane
Cop II - From ER to plasma membrane
Vesicle with KDEL amino acid sequence is going where?
It will associate with Cop I coat protein and go to ER
Vesicle with M6P signal is going where?
To endosome/lysosome via clathrin coat
What is the function of Rabs and SNAREs?
Docking of vesicle to target membrane
- Rabs bind to inositol phospholipids on membrane
- V-SNARES bind to T-SNARES
