Exam 3 Flashcards
Lipids are what?
Amphiphilic (hydrophilic and hyrdrophobic)
Make up 50% of membranes
What are the major lipids?
Phosphoglycerides, sphingolipids, and sterols
Sphingomyelin is derived from?
Sphingosine
The four phospholipids except sphingomyelin are derived from?
Glycerol
Cholesterol is?
A rigid planar sterol
Hydrophilic groups can?
Hydrogen bond with water but hydrophobic groups cannot
Amphiphilic molecules will spontaneously?
Form micelles or lipid bilayers in water
Caveolae are?
A lipid raft that does endocytosis
Lipid rafts are found in?
The lipid bilayer/membrane
Lipid droplets are what?
Organelles that store fatty acids in a monolayer of phospholipid
Glycolipids are assembled where?
Where are they found?
Assembled in the Golgi and delivered to membrane
Found on the non-cytosolic surface of lipid bilayers(membranes)
Membrane proteins anchor to a membrane through?
Either a fatty acid chain or a prenyl group attaching through amide linkage or thioester linkage to cysteine
Transmembrane domains contain?
Mainly non polar amino acids
Transmembrane proteins often contain?
Intrachain disulfide bonds and can be glycosylated
Glycocalyx are used for?
Cell recognition purposes
What can stain the membrane?
Carbohydrate binding proteins called lectins or ruthenium red
Spectrin does what?
Provides membrane with shape and structural integrity
Which of the following lipids has a net negative charge at physiological pH?
Phosphatidylserine
What is the carbohydrate layer on the outer surface of cells called?
Glycocalyx
What type of cell:cell junction would you expect to find at the basal plasma membrane of epithelial cells, connecting them to the basal lamina?
Hemidesmosomes
Artificial phospholipid bilayer vesicle formed from an aqueous suspension of phospholipid molecules
Liposome
Small region of the plasma membrane enriched in sphingolipids cholesterol
Lipid raft
Any glycolipid having one or more sialic acid residues in its structure; especially abundant in the plasma membranes of nerve cells
Ganglioside
Having both hydrophobic and hydrophilic regions, as in a phospholipid or a detergent molecule
Amphiphilic
The main type of phospholipid in animal cell membranes, with two fatty acids and a polar head group attached to a three carbon glycerol backbone
Phosphoglyceride
Lipid molecule with a characteristic four ring steroid structure that is an important component of the plasma membranes of animal cells
Cholesterol
Protein that binds tightly to a specific sugar
Lectin
The outer coat of a eukaryotic cell, composed of oligosaccharides linked to intrinsic plasma membrane glycoproteins and glycolipids, as well as proteins that have been secreted and reabsorbed onto the cell surface
Carbohydrate layer
Abundant protein associated with the cytosolic side of the plasma membrane in red blood cells, forming a rigid network that supports the membrane
Spectrin
Protein whose polypeptide chain crosses the lipid bilayer more than once
Multipass transmembrane protein
Pigmented protein found in the plasma membrane of Halobacterium halobium, where it pumps protons out of the cell in response to light
Bacteriorhodopsin
The complicated cytoskeletal network in the cytosol just beneath the plasma membrane
Cortex
Type of lipid linkage, formed as proteins pass through the endoplasmic reticulum, by which some proteins are attached to the noncytosolic surface of the membrane
Glycosylphosphatidylinositol anchor
An aqueous pore in a lipid membrane, with walls made of protein, through which selected ions or molecules can pass
Channel
The movement of a small molecule or ion across a membrane due to a difference in concentration or electrical charge
Passive transport
General term for a membrane embedded protein that serves as a carrier of ions or small molecules from one side of the membrane to the other
Membrane transport protein
Movement of a molecule across a membrane that is driven by ATP hydrolysis or other form of metabolic energy
Active transport
Driving force for ion movement that is due to differences in ion concentration and electrical charge on either side of the membrane
Electrochemical gradient
Large superfamily of membrane transport proteins that use the energy of ATP hydrolysis to transfer peptides and a variety of small molecules across membranes
ABC transporter
Type of ABC transporter protein that can pump hydrophobic drugs out of the cytoplasm of eukaryotic cells
Multidrug resistance protein
Membrane carrier protein that transports two different ions or small molecules across a membrane in opposite directions, either simultaneously or in sequence
Antiporter
Transport of solutes across an epithelium, by means of membrane transport proteins in the apical and basal surfaces of the epithelial cells
Transcellular transport
Carrier protein that transports two types of solute across the membrane in the same direction
Symporter
The adjustment in sensitivity of a cell or organism following repeated stimulation that allows a response even when there is a high background level of stimulation
Adaptation
The long lasting increase in the sensitivity of certain synapses in the hippocampus that is induced by a short burst of repetitive firing in the presynaptic neurons
Long term potentiation
Rapid, transient, self propagating electrical signal in the plasma membrane of a cell such as a neuron or muscle cell: a nerve impulse
Action potential
Quantitative expression that relates the equilibrium ratio of concentrations of an ion on either side of a permeable membrane to the voltage difference across the membrane
Nernst equation
A photosensitive ion channel that opens in response to light
Channelrhodopsin
Voltage difference across a membrane due to the slight excess of positive ions on one side and of negative ions on the other
Membrane potential
General term for a membrane protein that selectively allows cations such as Na+ to cross a membrane in response to changes in membrane potential
Voltage gated cation channel
That part of an ion channel structure that determines which ions it can transport
Selectivity filter
Insulating layer of specialized cell membrane wrapped around vertebrate axons
Myelin sheath
A K+ transporting ion channel in the plasma membrane of animal cells that remains open even in a resting cell
K+ leak channel
Long, thin nerve cell process capable of rapidly conducting nerve impulses over long distances so as to deliver signals to other cells
Axon
Transmembrane protein complex that forms a water filled channel across the lipid bilateral through which specific inorganic ions can diffuse down their electrochemical gradients
Ion channel
Specialized junction between a nerve cell and another cell, across which the nerve impulse is transferred, usually by a neurotransmitter, which is secreted by the nerve cell and diffuses to the target cell
Synapse
Small signaling molecule such as acetylcholine, glutamate, GABA, or glycine, secreted by a nerve cell at a chemical synapse to signal to the post-synaptic cell
Neurotransmitter
Technique in which the tip of a small glass electrode is sealed onto an area of cell membrane, thereby making it possible to record the flow of current through individual ion channels
Patch-clamp recording
Understand the basic structure, composition, and characteristics of lipid bilayers/membranes (phospholipids, glycolipids, sphingolipids, cholesterol)
Lipids are amphiphilic, the major lipids are phosphoglycerides
Lipids make up 50% of membranes
Glycolipids are found in monolayers facing away from the cytosol
Cholesterol is distributed roughly equally between both monolayers
Understand what it means for a lipid bilayer to be asymmetrical
The outside face of membrane is always different from the inner face of membrane
Know what a lipid raft is
Formed from a combination of weak protein-protein, protein-lipid, and lipid-lipid interactions to form a lipid raft in the membrane
Know what liposomes are
Synthetic lipid bilayers
Hydropathy plots show what?
Hydrophobicity of amino acids thus identifying transmembrane a-helical domains of membrane proteins
Basic structure of all cellular membranes include what?
Lipid molecules and membrane associated proteins
The most abundant membrane lipids are what?
Phospholipids
What are phospholipids composed of?
A polar head group and two hydrophobic hydrocarbon tails
The nonpolar tails of phospholipids vary in their what?
Length
What is a rigid structure attached to a polar hydroxyl head group and short nonpolar hydrocarbon tail?
Cholesterol
What packs in between phospholipids close to the nonpolar head groups?
Cholesterol
Cholesterol has an impact on what property of the lipid bilayer?
The permeability-barrier properties of the bilayer
Cholesterol makes the bilayer less permeable to what?
Small water soluble molecules
Does cholesterol change the fluid properties of the membrane?
No
Which are thinner: membranes composed of unsaturated phospholipids or membranes composed of saturated phospholipids?
Unsaturated phospholipids
Lipids rotate on their what?
Axis
Lipids exchange positions with neighboring lipids by what?
Lateral diffusion
Lipids molecules in the plasma membrane associate in specialized lipid sub domains referred to as what?
Lipid rafts
What regions are enriched with sphingolipids and cholesterol and are involved in organizing membrane proteins?
Lipid rafts
What are sugar modified lipids?
Glycolipids
What are localized to the outer leaflet of the plasma membrane bilayer?
Glycolipids
Assymetry is because sugar addition occurs only within the lumen of the what?
ER/Golgi
Glycolipids make up how much of all plasma membrane lipids?
-5%
What localized only to the inner leaflet of a plasma membrane?
Phosphotidylserine
What kind of proteins span the membrane at least once to generate domains that localized to both sides of the membrane?
Transmembrane proteins
What proteins pass through the membrane as either an amphipathic alpha-helix or a beta-sheet?
Transmembrane proteins
What types of proteins are typically localized to the cytosolic side of the plasma membrane?
Lipid anchors
What are reversible; converting a membrane bound protein into a soluble cytosolic one?
Lipid modifications
Most membrane proteins span the lipid bilayer as what?
Alpha helices
