Term
| What is the fundamental unit/structure of all biological membranes |
|
Definition
|
|
Term
| What is the general purpose of biological membranes |
|
Definition
| form a semi permeable barrier |
|
|
Term
| What are the two general types of molecules that make up lipid bilayers? |
|
Definition
| Proteins and phospholipids |
|
|
Term
| Compare and contrast prokaryotes and eukaryotes with regard to their membrane bound structures |
|
Definition
| Eukaryotes have organelles and nucleus, prokaryotes do not |
|
|
Term
| two classes of proteins, which are found in the plasma membrane of prokaryotic cells |
|
Definition
Transmembrane, integral proteins
Peripheral proteins |
|
|
Term
| Where is ATP synthesis carried out in prokaryotes? |
|
Definition
|
|
Term
| Where is ATP synthesis carried out in eukaryotes? |
|
Definition
|
|
Term
| What type of eukaryotic protein interacts with membrane proteins to give cells their characteristic shape and allow for movement? |
|
Definition
|
|
Term
|
Definition
| Consist of two segments: fatty acid-based (fatty acyl) hydrocarbon tail that is hydrophobic and Polar head group which is strongly hydrophilic, interacts with water molecules |
|
|
Term
| the types of amphipathic lipids found in biomembranes, besides the phospholipids. |
|
Definition
| glycolipids and cholesterol |
|
|
Term
| Are any lipids specific to animal species? |
|
Definition
|
|
Term
| Predict the behavior of amphipathic phospholipids in an aqueous environment |
|
Definition
| Phospholipids aggregate into one of three forms |
|
|
Term
|
Definition
| formation which has a hydrophobic interior composed entirely of fatty acyl chains |
|
|
Term
|
Definition
| spherical formation which consists of a phospholipid bilayer surrounding an aqueous center |
|
|
Term
| How would aggregation drive the formation of membrane bound structures/vesicles |
|
Definition
| Lumen is equivalent to extracellular space, external face becomes the internal face of the vesicle membrane, while in the vesicle the cytosolic face of the plasma membrane still faces the cytosol |
|
|
Term
| What types of chemical forces stabilize the lipid bilayer? |
|
Definition
| Van Der Waals forces and hydrophobic interactions stabilize the hydrophobic tails, ionic and hydrogen bonds stabilize the head groups |
|
|
Term
| Describe the structural parts of a typical phospholipid bilayer |
|
Definition
| Each phospholipid layer in the lamellar structure is called a leaflet |
|
|
Term
| List three basic properties of synthetic phospholipid bilayers |
|
Definition
(1) Virtually impermeable to water soluble solutes
(2) Stability
(3) Have ability to spontaneously form sealed closed compartments |
|
|
Term
| List three subcellular organelles, which have double membranes |
|
Definition
| nucleus, mitochrondria and chloroplast |
|
|
Term
| Name the three principal classes of lipids found in membranes |
|
Definition
Phosphoglycerides
Sphigolipids
Sterols |
|
|
Term
| Are all membrane lipids phospholipids? |
|
Definition
| No, all phosphoglycerides are phospholipids. |
|
|
Term
| Describe the basic structure of phosphoglycerides |
|
Definition
| Hydrophobic tail made of two fatty acid-based chains esterfied to the two hydroxyl groups in glycerol phosphate and Polar head group attached to the phosphate group |
|
|
Term
| What are phosphoglycerides derived from |
|
Definition
|
|
Term
| identify what part of a phosphoglyceride corresponds to the “polar head group” and what part corresponds to the hydrophobic tail. |
|
Definition
| Polar head groups are attached to the phosphate groups and Hydrophobic tail is made of two fatty acyl chains esterfied to the hydroxyl groups in glycerol |
|
|
Term
| Name four commonly occurring polar head groups |
|
Definition
| Phosphatidylethanolamine, phosphatidylcholine, phosphatidylserine, phosphatidylinositol |
|
|
Term
| Are the fatty acids found in biomembranes saturated or unsaturated? |
|
Definition
|
|
Term
| What are the implications of unsaturated fatty acids in terms of membrane structure? |
|
Definition
| Unsaturated fatty acids create a kink, preventing the fatty acids from packing together as tightly, thus decreasing the melting temperature (increasing the fluidity) of the membrane |
|
|
Term
| What types of bonds are found in a phosphoglyceride? |
|
Definition
|
|
Term
| What is the product of the reaction of a phospholipase with a phospholipid? |
|
Definition
| Produce lysophospholipids, which lack one of the two acyl chains |
|
|
Term
| What are lysophospholipids and what is their biological function? |
|
Definition
| Released from cells and recognized by specific receptors |
|
|
Term
|
Definition
| Group of phosphoglycerides that contain one fatty acyl chain attached to carbon 2 glycerol by an ester linkage and one long hydrocarbon chain attached to carbon 1 of glycerol by an ether rather than an ester linkage |
|
|
Term
| How do plasmalogens differ from traditional phospholipid? |
|
Definition
| The second hydrocarbon chain is attached to carbon one by an ether instead of an ester |
|
|
Term
| What types of tissue are plasmalogens common found in? |
|
Definition
| Human brain and heart tissue |
|
|
Term
| Describe the basic structure of sphigolipids |
|
Definition
| Contain a long-chain fatty acid attached in amide linkage to the sphingosine amino group |
|
|
Term
| What molecule are sphingolipids derived from? |
|
Definition
|
|
Term
| What is a glycosphingolipid? |
|
Definition
| Contains a single glucose unit attached to sphingosine |
|
|
Term
| In what type of tissue are significant amounts of glycolipids found? |
|
Definition
|
|
Term
| What is the relative percentage of glycolipids? |
|
Definition
| 2-10% of the total lipids in the plasma membrane |
|
|
Term
| What types of membrane sterols are found in animals? |
|
Definition
|
|
Term
| What types of membrane sterols are found in plants? |
|
Definition
|
|
Term
| What types of membrane sterols are found in fungi? |
|
Definition
|
|
Term
| Describe the general structure of sterols. |
|
Definition
|
|
Term
| Predict what cell types cholesterol is NOT found in |
|
Definition
| Prokaryotic and all plant cells |
|
|
Term
| Describe the structural packing of cholesterol in cells |
|
Definition
| They are intercalated into the membranes |
|
|
Term
| What is cholesterols effect on the structure/fluidity of the lipid bilayer? |
|
Definition
o Provide structural support
o Maintain membrane fluidity
o Confer necessary rigidity |
|
|
Term
| List the other non-membrane related functions of cholesterol in the body. |
|
Definition
| Precursor for several important bioactive molecules: Bile salts, steroid hormones, vitamin D, covalent attachment to hedgehog protein |
|
|
Term
| Could human survive without cholesterol? Why not? |
|
Definition
| No they are essential to membranes |
|
|
Term
| What are the sources of cholesterol in humans? |
|
Definition
|
|
Term
| How can cholesterol be regulated in humans? |
|
Definition
| lipid droplets contain excess cholesterol |
|
|
Term
| Describe the motion of lipids in the bilayer |
|
Definition
| Lipids can rotate freely along their axes and diffuse laterally within each leaflet |
|
|
Term
| What are the effects of temperature on lipid movement? |
|
Definition
| Rate of diffusion of lipids drops |
|
|
Term
| how can FRAP help us to understand the movement of lipids and proteins in the bilayer. |
|
Definition
| Phospholipid containing a fluorescent substituent is used to monitor lipid movement by applying a laser light focused on a small area of the surface, which bleaches the bound reagent and reduces the fluorescence in the illuminated area. The fluorescence of the bleached patch increases as unbleached surface molecules diffuse into it and bleached ones move out |
|
|
Term
| Describe how the lipid composition of membranes varies |
|
Definition
| Different types of cells generate membranes with differing lipid compositions |
|
|
Term
| a membrane with long unsaturated fatty acyl tails ... |
|
Definition
| have the greatest tendency to aggregate in a gel-like state |
|
|
Term
| a membrane with short saturated fatty acyl tails... |
|
Definition
| have less surface area and fewer van der waals interactions and form more fluid bilayers |
|
|
Term
| Kinks in unsaturated fatty acyl chains... |
|
Definition
| results in forming less table van der waals interactions with other lipids and a more fluid bilayer |
|
|
Term
| Straight saturated chains |
|
Definition
| can pack together tighter |
|
|
Term
| Exocytoplamic membranes contain |
|
Definition
| mostly sphingomyelin and PC (less fluid bilayers) |
|
|
Term
| Cytoplasmic membranes contain |
|
Definition
| PE, PS, and PI (more fluid bilayers) |
|
|
Term
| What is the biological activity of a “flippase"? |
|
Definition
| Catalyze movement of phosphoglycerides from one leaflet to another (via ATP) |
|
|
Term
|
Definition
| Micro domains of sphingomyelin and cholesterol which is surrounded by more fluid phospholipids |
|
|
Term
| What role does cholesterol play in maintaining lipid rafts? |
|
Definition
| Cholesterol maintains the integrity of the raft |
|
|
Term
| What is believed to be the physiological function of rafts? |
|
Definition
| Sense extracellular signals and transmit them into the cytosol |
|
|
Term
| What percentage do proteins contribute to membrane composition? |
|
Definition
| 76% of the inner mitochondrial membrane |
|
|
Term
| Identify what domains of a protein are transmembrane, extracellular, and cytoplasmic. |
|
Definition
Segments of the hydrophobic core of the phosphobilayer are transmembrane.
Segments associated with the exoplasmic or cytosolic leaflets are extracellular or cytoplasmic |
|
|
Term
| three ways in which proteins are found to interact with membranes in nature |
|
Definition
Integral- span the bilayer and comprise three segments: cytosolic, exoplasmic, and membrane-spanning domain
Lipid-anchored- bound covalently to one or more lipids embedded in one leaflet of the membrane and anchors protein to the membrane
Peripheral- bound to the membrane either indirectly with interactions with integral membrane proteins or with interactions with polar head groups |
|
|
Term
| Describe the protein secondary structural characteristics of transmembrane domains |
|
Definition
| Transmembrane domains contain alpha helices |
|
|
Term
| How can this be used to predict membrane protein topology? |
|
Definition
| An alpha helix is a continuous segment of 20-25 hydrophobic amino acids, the predicted length is just enough to span the membrane. Polar groups of the alpha helix are shielded from the hydrophobic interior of the membrane and form a hydrogen bond with an amide hydrogen 4 residues toward the C terminus |
|
|
Term
| Single pass transmembrane proteins |
|
Definition
| contain only one membrane spanning alpha helix |
|
|
Term
| Example of a single pass transmembrane protein |
|
Definition
|
|
Term
|
Definition
| contains several transmembrane alpha helices |
|
|
Term
| Example of a multi-pass protein |
|
Definition
|
|
Term
|
Definition
| Barrel shaped structure with a hydrophilic pore in the center |
|
|
Term
| In general what functional role do the transmembrane domains play? |
|
Definition
|
|
Term
| What role do lipid anchors play in attaching membranes to the bilayer? |
|
Definition
| Lipid anchors can hold water soluble proteins to one side of the leaflet |
|
|
Term
| List the three common mechanisms of anchoring. |
|
Definition
Cytosolic proteins linked to cytosolic faces via fatty acyl group covalently attached to N-terminal glycine via acylation
Cytosolic proteins attached to cytosolic face by hydrocarbon chain attached to cysteine near C terminal via prenylation
Proteoglycans bound to exoplasmic face by GPI |
|
|
Term
|
Definition
| Membrane topology refers to the orientation of the protein in the membrane |
|
|
Term
| how does membrane topology apply to membrane proteins |
|
Definition
| Cytosolic segments are always facing the cytoplasm and exoplasmic segments are always facing the opposite side of the cytoplasm |
|
|
Term
| Is topology fixed for proteins or does it vary? |
|
Definition
|
|
Term
| Describe the role of transmembrane glycoproteins in cell surface markers |
|
Definition
| Oriented so that all carbohydrate chains are in the exoplasmic domain |
|
|
Term
| Describe the basis of A; B and O blood groups in terms of membrane glycoproteins |
|
Definition
| Segments of glycoproteins and glycolipids expressed on surfaces of human red blood cells. People who are A blood type have an added monosaccharide to their cells which form an A antigen |
|
|
Term
| Describe the role of “lipid-binding” motifs in peripheral membrane protein function |
|
Definition
| They target the peripheral proteins to the membrane and bind to the polar head groups to carry out their function |
|
|
Term
| How can lipid binding motifs be used to predict the unknown function of a protein? |
|
Definition
| The amino acids composition of the protein can tells us if it might bind to the polar head groups and change something about them, i.e. phospholipase hydrolyze various bonds in the head group so the contain a lipid binding motif because they bind to the lipid head group |
|
|
Term
| Describe the differential solubilization of the various classes of membrane proteins |
|
Definition
| Ionic detergents bind to exposed hydrophobic regions of the membrane proteins and to they hydrophobic core of the water-soluble proteins. At high concentrations nonionic detergents soluble biological membranes. At low concentrations they bind to hydrophobic regions of most integral membrane proteins |
|
|
Term
| How can solubilization using detergents be used to determine whether a protein is an integral versus peripheral membrane protein? |
|
Definition
| Hydrophobic parts of nonionic detergents bind to hydrophobic segments of transmembrane proteins. Detergent solubilized transmembrane proteins can be purified. High ionic detergents with remove peripheral proteins |
|
|
Term
| What is the fundamental unit/structure of all biological membranes |
|
Definition
|
|
Term
| What is the general purpose of biological membranes |
|
Definition
| form a semi permeable barrier |
|
|
Term
| What are the two general types of molecules that make up lipid bilayers? |
|
Definition
| Proteins and phospholipids |
|
|
Term
| Compare and contrast prokaryotes and eukaryotes with regard to their membrane bound structures |
|
Definition
| Eukaryotes have organelles and nucleus, prokaryotes do not |
|
|
Term
| two classes of proteins, which are found in the plasma membrane of prokaryotic cells |
|
Definition
Transmembrane, integral proteins
Peripheral proteins |
|
|
Term
| Where is ATP synthesis carried out in prokaryotes? |
|
Definition
|
|
Term
| Where is ATP synthesis carried out in eukaryotes? |
|
Definition
|
|
Term
| What type of eukaryotic protein interacts with membrane proteins to give cells their characteristic shape and allow for movement? |
|
Definition
|
|
Term
|
Definition
| Consist of two segments: fatty acid-based (fatty acyl) hydrocarbon tail that is hydrophobic and Polar head group which is strongly hydrophilic, interacts with water molecules |
|
|
Term
| the types of amphipathic lipids found in biomembranes, besides the phospholipids. |
|
Definition
| glycolipids and cholesterol |
|
|
Term
| Are any lipids specific to animal species? |
|
Definition
|
|
Term
| Predict the behavior of amphipathic phospholipids in an aqueous environment |
|
Definition
| Phospholipids aggregate into one of three forms |
|
|
Term
|
Definition
| formation which has a hydrophobic interior composed entirely of fatty acyl chains |
|
|
Term
|
Definition
| spherical formation which consists of a phospholipid bilayer surrounding an aqueous center |
|
|
Term
| How would aggregation drive the formation of membrane bound structures/vesicles |
|
Definition
| Lumen is equivalent to extracellular space, external face becomes the internal face of the vesicle membrane, while in the vesicle the cytosolic face of the plasma membrane still faces the cytosol |
|
|
Term
| What types of chemical forces stabilize the lipid bilayer? |
|
Definition
| Van Der Waals forces and hydrophobic interactions stabilize the hydrophobic tails, ionic and hydrogen bonds stabilize the head groups |
|
|
Term
| Describe the structural parts of a typical phospholipid bilayer |
|
Definition
| Each phospholipid layer in the lamellar structure is called a leaflet |
|
|
Term
| List three basic properties of synthetic phospholipid bilayers |
|
Definition
(1) Virtually impermeable to water soluble solutes
(2) Stability
(3) Have ability to spontaneously form sealed closed compartments |
|
|
Term
| List three subcellular organelles, which have double membranes |
|
Definition
| nucleus, mitochrondria and chloroplast |
|
|
Term
| Name the three principal classes of lipids found in membranes |
|
Definition
Phosphoglycerides
Sphigolipids
Sterols |
|
|
Term
| Are all membrane lipids phospholipids? |
|
Definition
| No, all phosphoglycerides are phospholipids. |
|
|
Term
| Describe the basic structure of phosphoglycerides |
|
Definition
| Hydrophobic tail made of two fatty acid-based chains esterfied to the two hydroxyl groups in glycerol phosphate and Polar head group attached to the phosphate group |
|
|
Term
| What are phosphoglycerides derived from |
|
Definition
|
|
Term
| identify what part of a phosphoglyceride corresponds to the “polar head group” and what part corresponds to the hydrophobic tail. |
|
Definition
| Polar head groups are attached to the phosphate groups and Hydrophobic tail is made of two fatty acyl chains esterfied to the hydroxyl groups in glycerol |
|
|
Term
| Name four commonly occurring polar head groups |
|
Definition
| Phosphatidylethanolamine, phosphatidylcholine, phosphatidylserine, phosphatidylinositol |
|
|
Term
| Are the fatty acids found in biomembranes saturated or unsaturated? |
|
Definition
|
|
Term
| What are the implications of unsaturated fatty acids in terms of membrane structure? |
|
Definition
| Unsaturated fatty acids create a kink, preventing the fatty acids from packing together as tightly, thus decreasing the melting temperature (increasing the fluidity) of the membrane |
|
|
Term
| What types of bonds are found in a phosphoglyceride? |
|
Definition
|
|
Term
| What is the product of the reaction of a phospholipase with a phospholipid? |
|
Definition
| Produce lysophospholipids, which lack one of the two acyl chains |
|
|
Term
| What are lysophospholipids and what is their biological function? |
|
Definition
| Released from cells and recognized by specific receptors |
|
|
Term
|
Definition
| Group of phosphoglycerides that contain one fatty acyl chain attached to carbon 2 glycerol by an ester linkage and one long hydrocarbon chain attached to carbon 1 of glycerol by an ether rather than an ester linkage |
|
|
Term
| How do plasmalogens differ from traditional phospholipid? |
|
Definition
| The second hydrocarbon chain is attached to carbon one by an ether instead of an ester |
|
|
Term
| What types of tissue are plasmalogens common found in? |
|
Definition
| Human brain and heart tissue |
|
|
Term
| Describe the basic structure of sphigolipids |
|
Definition
| Contain a long-chain fatty acid attached in amide linkage to the sphingosine amino group |
|
|
Term
| What molecule are sphingolipids derived from? |
|
Definition
|
|
Term
| What is a glycosphingolipid? |
|
Definition
| Contains a single glucose unit attached to sphingosine |
|
|
Term
| In what type of tissue are significant amounts of glycolipids found? |
|
Definition
|
|
Term
| What is the relative percentage of glycolipids? |
|
Definition
| 2-10% of the total lipids in the plasma membrane |
|
|
Term
| What types of membrane sterols are found in animals? |
|
Definition
|
|
Term
| What types of membrane sterols are found in plants? |
|
Definition
|
|
Term
| What types of membrane sterols are found in fungi? |
|
Definition
|
|
Term
| Describe the general structure of sterols. |
|
Definition
|
|
Term
| Predict what cell types cholesterol is NOT found in |
|
Definition
| Prokaryotic and all plant cells |
|
|
Term
| Describe the structural packing of cholesterol in cells |
|
Definition
| They are intercalated into the membranes |
|
|
Term
| What is cholesterols effect on the structure/fluidity of the lipid bilayer? |
|
Definition
o Provide structural support
o Maintain membrane fluidity
o Confer necessary rigidity |
|
|
Term
| List the other non-membrane related functions of cholesterol in the body. |
|
Definition
| Precursor for several important bioactive molecules: Bile salts, steroid hormones, vitamin D, covalent attachment to hedgehog protein |
|
|
Term
| Could human survive without cholesterol? Why not? |
|
Definition
| No they are essential to membranes |
|
|
Term
| What are the sources of cholesterol in humans? |
|
Definition
|
|
Term
| How can cholesterol be regulated in humans? |
|
Definition
| lipid droplets contain excess cholesterol |
|
|
Term
| Describe the motion of lipids in the bilayer |
|
Definition
| Lipids can rotate freely along their axes and diffuse laterally within each leaflet |
|
|
Term
| What are the effects of temperature on lipid movement? |
|
Definition
| Rate of diffusion of lipids drops |
|
|
Term
| how can FRAP help us to understand the movement of lipids and proteins in the bilayer. |
|
Definition
| Phospholipid containing a fluorescent substituent is used to monitor lipid movement by applying a laser light focused on a small area of the surface, which bleaches the bound reagent and reduces the fluorescence in the illuminated area. The fluorescence of the bleached patch increases as unbleached surface molecules diffuse into it and bleached ones move out |
|
|
Term
| Describe how the lipid composition of membranes varies |
|
Definition
| Different types of cells generate membranes with differing lipid compositions |
|
|
Term
| a membrane with long unsaturated fatty acyl tails ... |
|
Definition
| have the greatest tendency to aggregate in a gel-like state |
|
|
Term
| a membrane with short saturated fatty acyl tails... |
|
Definition
| have less surface area and fewer van der waals interactions and form more fluid bilayers |
|
|
Term
| Kinks in unsaturated fatty acyl chains... |
|
Definition
| results in forming less table van der waals interactions with other lipids and a more fluid bilayer |
|
|
Term
| Straight saturated chains |
|
Definition
| can pack together tighter |
|
|
Term
| Exocytoplamic membranes contain |
|
Definition
| mostly sphingomyelin and PC (less fluid bilayers) |
|
|
Term
| Cytoplasmic membranes contain |
|
Definition
| PE, PS, and PI (more fluid bilayers) |
|
|
Term
| What is the biological activity of a “flippase"? |
|
Definition
| Catalyze movement of phosphoglycerides from one leaflet to another (via ATP) |
|
|
Term
|
Definition
| Micro domains of sphingomyelin and cholesterol which is surrounded by more fluid phospholipids |
|
|
Term
| What role does cholesterol play in maintaining lipid rafts? |
|
Definition
| Cholesterol maintains the integrity of the raft |
|
|
Term
| What is believed to be the physiological function of rafts? |
|
Definition
| Sense extracellular signals and transmit them into the cytosol |
|
|
Term
| What percentage do proteins contribute to membrane composition? |
|
Definition
| 76% of the inner mitochondrial membrane |
|
|
Term
| Identify what domains of a protein are transmembrane, extracellular, and cytoplasmic. |
|
Definition
Segments of the hydrophobic core of the phosphobilayer are transmembrane.
Segments associated with the exoplasmic or cytosolic leaflets are extracellular or cytoplasmic |
|
|
Term
| three ways in which proteins are found to interact with membranes in nature |
|
Definition
Integral- span the bilayer and comprise three segments: cytosolic, exoplasmic, and membrane-spanning domain
Lipid-anchored- bound covalently to one or more lipids embedded in one leaflet of the membrane and anchors protein to the membrane
Peripheral- bound to the membrane either indirectly with interactions with integral membrane proteins or with interactions with polar head groups |
|
|
Term
| Describe the protein secondary structural characteristics of transmembrane domains |
|
Definition
| Transmembrane domains contain alpha helices |
|
|
Term
| How can this be used to predict membrane protein topology? |
|
Definition
| An alpha helix is a continuous segment of 20-25 hydrophobic amino acids, the predicted length is just enough to span the membrane. Polar groups of the alpha helix are shielded from the hydrophobic interior of the membrane and form a hydrogen bond with an amide hydrogen 4 residues toward the C terminus |
|
|
Term
| Single pass transmembrane proteins |
|
Definition
| contain only one membrane spanning alpha helix |
|
|
Term
| Example of a single pass transmembrane protein |
|
Definition
|
|
Term
|
Definition
| contains several transmembrane alpha helices |
|
|
Term
| Example of a multi-pass protein |
|
Definition
|
|
Term
|
Definition
| Barrel shaped structure with a hydrophilic pore in the center |
|
|
Term
| In general what functional role do the transmembrane domains play? |
|
Definition
|
|
Term
| What role do lipid anchors play in attaching membranes to the bilayer? |
|
Definition
| Lipid anchors can hold water soluble proteins to one side of the leaflet |
|
|
Term
| List the three common mechanisms of anchoring. |
|
Definition
Cytosolic proteins linked to cytosolic faces via fatty acyl group covalently attached to N-terminal glycine via acylation
Cytosolic proteins attached to cytosolic face by hydrocarbon chain attached to cysteine near C terminal via prenylation
Proteoglycans bound to exoplasmic face by GPI |
|
|
Term
|
Definition
| Membrane topology refers to the orientation of the protein in the membrane |
|
|
Term
| how does membrane topology apply to membrane proteins |
|
Definition
| Cytosolic segments are always facing the cytoplasm and exoplasmic segments are always facing the opposite side of the cytoplasm |
|
|
Term
| Is topology fixed for proteins or does it vary? |
|
Definition
|
|
Term
| Describe the role of transmembrane glycoproteins in cell surface markers |
|
Definition
| Oriented so that all carbohydrate chains are in the exoplasmic domain |
|
|
Term
| Describe the basis of A; B and O blood groups in terms of membrane glycoproteins |
|
Definition
| Segments of glycoproteins and glycolipids expressed on surfaces of human red blood cells. People who are A blood type have an added monosaccharide to their cells which form an A antigen |
|
|
Term
| Describe the role of “lipid-binding” motifs in peripheral membrane protein function |
|
Definition
| They target the peripheral proteins to the membrane and bind to the polar head groups to carry out their function |
|
|
Term
| How can lipid binding motifs be used to predict the unknown function of a protein? |
|
Definition
| The amino acids composition of the protein can tells us if it might bind to the polar head groups and change something about them, i.e. phospholipase hydrolyze various bonds in the head group so the contain a lipid binding motif because they bind to the lipid head group |
|
|
Term
| Describe the differential solubilization of the various classes of membrane proteins |
|
Definition
| Ionic detergents bind to exposed hydrophobic regions of the membrane proteins and to they hydrophobic core of the water-soluble proteins. At high concentrations nonionic detergents soluble biological membranes. At low concentrations they bind to hydrophobic regions of most integral membrane proteins |
|
|
Term
| How can solubilization using detergents be used to determine whether a protein is an integral versus peripheral membrane protein? |
|
Definition
| Hydrophobic parts of nonionic detergents bind to hydrophobic segments of transmembrane proteins. Detergent solubilized transmembrane proteins can be purified. High ionic detergents with remove peripheral proteins |
|
|
Term
| Describe the general process by which fatty acids are assembled. |
|
Definition
| Synthesized from acetyl- coA by water-soluble enzymes and modified by elongation and desaturation in the ER |
|
|
Term
| Name the important enzymes in fatty acid synthesis process. |
|
Definition
| Acetyl-CoA carboxylase and fatty acid synthase |
|
|
Term
| Name the class of proteins, which aid in the movement of synthesized fatty acids. |
|
Definition
| Fatty Acid binding proteins (FABPs) |
|
|
Term
| What is the unique secondary structure of FABPs |
|
Definition
| Hydrophobic pocket lined by beta sheets |
|
|
Term
| Describe the principal cellular location of incorporation of fatty acids into phospholipids. |
|
Definition
| Cytosolic face of the ER membrane in order to be synthesized |
|
|
Term
| How do phospholipids move from the cytosolic leaflet to the exocytosolic leaflet during membrane biogenesis? |
|
Definition
| Flippases move switch them |
|
|
Term
| Describe the cellular location of the enzymes, which synthesize cholesterol |
|
Definition
|
|
Term
| Describe the mechanism of action of the STATIN class of drugs in lowering cholesterol. |
|
Definition
| Bind to HMG0CoA reductase and directly inhibit its activity which lowers cholesterol synthesis |
|
|
Term
| Describe the 3 mechanisms by which cholesterol is transported between organelles in the cell. |
|
Definition
(1) Budding from the ER and fuse with membranes in the Golgi complex, then bud from the Golgi and fuse with the plasma membrane
(2) Protein mediated contact of ER or ER-derived membranes with membranes of other organelles
(3) Small transfer proteins facilitate the exchange of phospholipids between different membranes |
|
|
Term
| What proteins are involved in cholesterol transport? |
|
Definition
|
|
Term
| Cholesterol can mix into a membrane because it's |
|
Definition
|
|
Term
|
Definition
different biomembranes contain different proportions of the same phospholipids, the two leaflets of the biomembrane contain different leaflets, and some phospholipids and cholesterol may cluster to form lipid rafts
NO biomembranes have free edges |
|
|
Term
| Which lipids are present in biomembranes? |
|
Definition
| phosphoglycerides, sphingolipids, steriods |
|
|
Term
| phospholipids with short or unsaturated fatty acyl chains? |
|
Definition
| increase membrane fluidity |
|
|
Term
| lipid droplets derive from |
|
Definition
|
|
Term
| peripheral membrane proteins |
|
Definition
| may convalently interact with phospholipid heads |
|
|
Term
| Integral membrane proteins are |
|
Definition
|
|
Term
|
Definition
| allow small water soluble molecules to pass through the membrane |
|
|
Term
| glycoproteins and glycolipids are abundant in the |
|
Definition
|
|
Term
| movement of phospholipids from one leaflet to another requires |
|
Definition
|
|
Term
| The major site of lipid synthesis in eukaryotic cells is |
|
Definition
|
|
Term
| phosphate containing lipids include |
|
Definition
| plasmalogen, phospholipids, and sphingolipids NOT triglycerides |
|
|
Term
| cholesterol, bile acids, ergoterol, and stigmasol share.. |
|
Definition
| four ring structure, hydroxl group on first ring, multiple carbon chains extending off the ring structure NOT carboxylic acid group |
|
|
Term
| The enzyme in cholesterol synthesis subject to feedback inhibition is |
|
Definition
|
|
Term
| cholesterol and phospholipids are transported between organelles by |
|
Definition
| imcompletely characaterized vesicle populations and direct contact between membranes and soluble lipid transfer proteins |
|
|
