Cell Structure and Function Flashcards
Name the four major categories of membrane phospholipids.
Amino (phosphatidyl-ethanolamine, phosphatidyl serine (-))
Choline (phosphatidyl-choline, sphingo-myelin) Phosphoglycerides (Aminos + Phos-choline) Sphingolipid (Sphingo-myelin)
Name three effects of cholesterol in the phospholipid membrane.
stiffens membrane
reduces permeability
inhibits phase changes
Which phospholipid eventually flipped and face cytosolic surface as membrane moves from ER to Golgi to membrane?
Amino Phospholipids
What is a signal for cell death with repect to phospholipids?
The flipping of the negative phosphatidyl-serine to non-cytosolic side. Scramblase flips sporatically so charge is evened out.
Glycolipids face the [ ] side of the cell and prevent [ ] from interacting with the small intestine.
Non-cytosolic side; digestive enzyme.
They also form thicker patches (lipid rafts) in the small intestine for protection.
Inositol phospholipids have multiple locations to be phosphorylated and are crucial to cell function (T/F)
T
Name some functions of phosphatidylinositol:
Serving as a binding site for cytosolic membrane-associated proteins and enzymes
Anchoring proteins to the plasma membrane
Cell signaling, including protein kinase C and Ca++ second messenger regulation
Identifying specific organelle membranes and regulating organelle function
Controlling vesicular trafficking
Modulating ion channel activity
Regulating secretion
Chemotaxis and immune cell function
Neuronal growth and synaptic signaling
Which of these movements for phospholipids is rare? Flexing Rotation, Flipping Lateral Movement
Flipping (if not accompanied by flipase/scramblase)
Choline phospholipids eventually end up on which side?
Non-cytosolic leaflet
Flipases do not show specificity for which PPlipid is flips while scramblases show specificity (T/F)
F, the opposite is true: Flipases = selective, Scramblases = no specificity
How can membrane proteins organize themselves?
Attach to extra or intracellular matrix, bind to another cell, or aggregate.
What is the name of the long protein where mutation sites lead to muscular dystrophy?
Dystrophin
Name one similarity and one difference of Hereditary spherocytosis when comparing to muscular dystrophy.
Similar in that it involves mutations for proteins involved in mechanical support of plasma membrane, but it’s different in that it affects RBC, not muscle cells.
Membrane protein orientation is determined by:
The number and orientation of the stop/start sequence(s).
N-linked glycosylated proteins are attached to [ ] and it is located on the [ ] side.
Asparagine; non-cytosolic side.
Because the glycosyl transferase enzymes that do this are located in the ER lumen, the sugar groups of these glycoproteins are always located on the non-cytosolic side of membranes.
O-linked glycosylated proteins are attached to [ ] and the sugar is added in the [ ].
Serine and Threonine; Golgi
How do misfolded proteins get degraded?
They leave the ER, are ubiquitanated, and fed through proteasomes that are only located in the cytosol.
What are the three major destinations that the golgi transports vesicles?
- Lysosomes
- Secretory vesicles
- Plasma membrane
What is the connection between the golgi and N-linked glycoproteins?
The Golgi modifies those glycoproteins when they arrive from the ER.
What are the three pathways through which vesicle leave from the Golgi?
- ) Constituted: Default, all cells do this to recycle PM.
- ) Regulated: Secretes in specific manner
- ) Formation of Lysosomes
Name the three pathways that lead to a lysosome.
Autophagy (a survival cell mechanism), phagocytosis, and fusion with endosome to eventually form a lysosome.
Caveolin inserts into the cytosolic leaflet, causes it to curve, and forms a vesicle. (T/F)
T
These are the two types of coat proteins. (Can you name their functions?)
Clathrin - distal transport (PM, Lysosome, endosomes)
Coatamer (cop) proteins - proximal transport between ER and golgi
Cargo proteins and clathrin have no link. (T/F)
F, adapter proteins do this.
How do GDP and GTP affect COP-I and COP-II?
GTP turns on G proteins, GDP turns G protein off when they are binding the COP proteins. GEFs turn on, GAFs turn off, small G proteins.
What are the three sets of proteins that aid in accurate delivery and fusion of vesicles?
Rab, Rab effectors, and SNAREs. All of these are aided by inositol phospholipids.
