quiz 2 Flashcards
FRAP = Fluorescence Recovery After Photobleaching
method for determining movement of proteins by bleaching a pool of molecules in one area and watching the area fill back in (or not)
Lateral diffusion of proteins in cell membrane
FRET = Fluorescence Resonance Energy Transfer
method for determining if two proteins are close to one another in cells by exciting a fluoror bound to one and looking for excitation and emission of signal from the other proximity
dependent
without external excitation
Specific membrane compartments such ______&_____ as can be isolated from cell lysates by differential centrifugation?
lysosomes and peroxisomes
Gel filtration chromatography can seperate
separate proteins based on size/shape
____________ have different separation properties that will
cause proteins to interact with them in distinct ways.
column chromatography matrices
The structure or conformation of a protein can be predicted
by
NMR, X-Ray crystallography
Mass spectrometry
method of determining protein identity and modification proteomics
altering gene sequences can be Gene regulatory sequences or protein coding sequences or
(expression change) (gene product change
, RISC complex, that also functions in regulating different genes by _____encoded by the genome.
miRNAs
Southern Blot :
Northern Blot :
DNA
RNA
Proteins can stably associate with membranes by
Hydrophobic transmembrane segments
Posttranslationally added lipid groups that are covalently linked to proteins
Association with other membrane localized proteins
Phospholipids that have shorter fatty acid tails or tails which contain unsaturated hydrocarbons cause membranes to be
more fluid
When observing the movements of phospholipids in membranes, which of the following occurs least frequently
Movements between the leaflets of a membrane bilayer
All transmembrane proteins float and diffuse freely in the bilayer of the plasma membrane in the same manner as phospholipids
false
Membrane compartments in eukaryotic cells maintain lipid bilayers whose contents are typically symmetric in their distribution across both leaflets
false
Proteins that aid the movement of phospholipids from one leaflet of a membrane bilayer to another are known as
flippses
The best way to determine if a protein is able to move in a membrane would be
FRAP
3 major phospholipids
Phosphatidylcholine
Phosphatidylethanolamine
Phosphatidylserine
Phospholipids rotate….
diffuse and flip flop
Membrane fluidity depends on composition and
length of the phospholipid hydrocarbon tails
An increase in cholesterol will tend to make membranes:
Stiffer/less permeable
Cholesterol and other sterols help control fluidity, filling in spaces between phospholipids and thereby
stiffening the membrane and reducing permeability
New membrane phospholipids are first synthesized and inserted into membranes where
The cytosolic surface of the ER
Lipid synthesis can only be possilbe with roles of
flippases (cytolsol) and scramblases (cell exterior)
Cellular membranes are –_______
and ______also generate and maintain this
asymmetric Flippases
Glycolipids and glycoproteins occur only or mainly in
outer leaflet of the plasma membrane
3 mechanisms for membrane localization of proteins
Membrane Associated alpha helix or beta sheet Lipid anchor addition Integral Membrane Proteins
Membrane spanning proteins are typically extracted from membranes by using
Addition of detergents such as SDS
Proteins play major roles in modulating membrane dynamics and organization
flippases fusion catalysts
‘coupling’ proteins for other proteins
diffusion barriers
Note: proteins without
sorting signals will
by default remain in
the cytosol
