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Stack #110096
| Membrane Proteins and Lipids | Membrane Proteins and Lipids |
|---|---|
| What is the most abundant lipid in the cell membrane? | Phospholipids |
| What percent of total lipid content does phospholipids share? | 50-90% |
| List the composition of lipids in the membrane in terms of abundance. | Phospholipids (50-90%), Sterols (5-25%) and Glycolipids (less than 5%) |
| Describe the structure of a phospholipid | It has a hydrophillic polar head and a hydrophobic tail. The head has a phosphate group esterified to an alcohol. The hydrophobic tail is bade of two faddy acid chains. |
| In lipid bilayer, unsaturated fatty acids are in the cis or trans configuration? | cis |
| What makes the lipid bilayer more fluid? | unsaturated fatty acids , short acyl chains, less cholesterol. |
| What contributes to more rigid lipid bilayer? | long acyl chains, cholesterol and saturated fatty acyl chains. |
| What are sphingolipids | lipids that contain amino-alcohol sphingosine |
| What are sphingolipids classified into? | Ceramides, sphingomyelins, and glycosphingolipids |
| What is the role of sphingolipids | 1. maintenance of membrane structure, 2. Modulate behavior of GF receptors, 3. Binding site for microbial toxins, viruses 4. Signaling molecule |
| What disease results from disorder of sphingolipid emtabolism | Gaucher's disease |
| What is a glycolipid? | contain hydrophobic hydrocarbon tails, polar region with one or more sugar and NO PHOSPHATE |
| What is the simplest glycolipid | cerebroside |
| How many sugar does a cerebroside contain? | 1 sugar |
| What is a ganglioside? | a glycolipid with branched chain of as many as seven sugar residues. |
| Where are gangliosides most abundant? | In gray matter of human brain |
| What is role of gangliosides | role in interactions between cells and immune response. |
| What disease are associated with gangliosides? | found in tumors, Tay-Sachs disease (accumulate in the nerve cells in brain and other tissues--gangliosides not degrade because of insufficient activity of specific enzyme that catalyzes biodegradation of gangliosides. |
| What is the structure of cholesterol? | rigid 4 ring system and short branched hydrocarbon tail. |
| Is cholesterol amphipathid? | Yes, due to hydroxyl group presence. |
| What does the OH group of cholesterol associate with in the lipid membrane? | It forms hydrogen bonds with polar phospholipid head groups |
| What is bile acid derived from? | From cholesterol. |
| What allows spontaneous formation of lipid bilayer? | amphipathic properties of phospholipids |
| Why do lipids form bilayer and not micelle? | two fatty acyl chains are too bulky to fit into the interior of a micelle |
| What are 3 important features of lipid bilayer? | 1. self assembly driven by hydrophobic interactions. 2. Close packing 3. Ability to fuse and extend (i.e. endocytosis etc.) |
| What is used to disrupt the structure of lipied bilayer and to isolate proteins? | detergents |
| Is the lipid bilayer assymentrical? | yes |
| where are lipids synthesized? | in the SER |
| In the Golgi, where can sugars be modified on glycolipids? | only on the inside where the enzymes are |
| Is the % of cholestrol different in each layer of the lipid bilayer? | no |
| Are peripheral proteins covalently linked to lipids or interaction tightly with transmembrane proteins? | both |
| Can peripheral proteins be moved from the membrane by treatment with enzymes or reagents without disrupting membrane integrity? | yes |
| What is the fluid mosaic model? | 1. Membranes are 2D solutions of lipids and proteins. 2. Lipid bilayer has dual role: permeability barrier and regulate protein activity 3. Membrane proteins are free to diffuse laterally, not not rotate form one side of the membrane to the other. |
| How is the shpae of the cell and the mechanical properties of the plasma membrane? | By the cell cortex. |
| What is the cell cortex? | A meshwork of fibrous proteins attached to cytosolic face of membrane. |
| What is the main component of cell cortex? | spectrin |
| What is spectrin? | a long, thin and flexible rod-like protien (100 nm long) |
| What disease occurs from spectirin structure abnormaliities? | Anemia, due to fewer, spherical and very fragile red cells |
| What is the role of glycocalyx? | protect cell surface form mechanical and chemical damabes and lubricates surface |
| What is glycocalyx made of? | Carbohydrates form glycoproteins, proteoglycans, and glycolipids on non-cytostolic side of membrane |
| What kind of protens are most abundant on plasma membrane? | glycoproteins |
| What are glycoproteins? | short canins fo sugar molecules attached to protein |
| What are proteoglycans? | membrane proteins with one or more long polysacharide chains attached. |
Created by:
pachida
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