cell biology review
Card Set Information
cell biology review
cell biology review pathology
cell biology review, pathology
describe the membrane system.
plasma membrane and membrane of organelles
all has common structure
: lipid and protein molecules held by noncovalent interactions
dynamic fluid structures; many molecules can move in and out of plane
Describe the lipid bilayer.
double layer lipid about 5 nm thick
almost all lipids are amphipathic with hydrophilic polar end and hydrophobic non-polar end
most lipids are phospholipids
cholesterol and glycoplipids are found on membranes. What are they?
cholesterol makes membrane more rigid
glycolipids (lipids with attached sugar residues)
biological membranes differe in their _______ and ____ composition.
lipid and protein
What are the jobs of protein on membrane?
transport of ions and polar molecules
binding of hormones and cytokines
signal transduction across the membrane
and structural stabilization of the lipid bilayer.
Ratio of protein:lipid determine their _____. Ex. myelin sheath...
myelin sheath with very low protein:lipid ratio
What are transmembrane proteins?
extend through the lipid bilayer
has both hydrophilic and phobic regions
another name = integral proteins
pass thru membrane once (growth factor receptors) or many times (transporters and membrane channels)
what are surface proteins?
covalently attached to the lipid bilayer
have post-translational modifications such as fatty acids, prenyl groups or oligosaccharides that attach to the protein to the surface
what are Peripheral proteins?
bound to the membrane by noncovalent interactions with other membrane proteins.
what is the function of plasma membrane?
encloses the cell, defines its boundary, and maintains the essential differences between the cytoplasm and extracellular environment.
transducing signals and the transport of metabolites between the intra- and extra-cellular compartments.
Describe ER and what is the function?
branching tubules and sacs that extends throughout
all interconnect to form a continuous sheet enclosing an internal space - ER lumen
~50% of the total area
: with ribosomes, synthesis of membrane and secretory proteins
: membrane lipid biogenesis
ex. improper folding proteins = toxic effects = liver damage in antitrypsin deficiency
describe golgi apparatus and its function.
flattened, stacked membranes or sacs (cisternae)
modification, packing and sorting of macromolecules for secretion and delivery to other organelles
receives lipids and proteins from the ER and sends them to a variety of destinations
covalently modifying them (e.g. glycosylation, phosphorylation) along the way.