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59 Cards in this Set
- Front
- Back
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Define fluid mosaic model |
Fluid means that it is always moving and the mosaic means that it is made up of many different constituents (lipids, proteins etc.) |
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What are the major constituents of the cell? |
Proteins and liids |
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What function does the membrane have in reference to other cells and EC environment? |
It separates it from other cells and the environment ( selective permeable membrane) |
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What constituent is the most abundant in cells? |
Proteins (55%) |
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What fat forms contribute to the fluidity of the cell? |
Unsaturated phospholipids - the kink |
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What makes the membranes less fluid and more stable? |
Cholesterol - rigid molecule |
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What are the cellular movements of the lipids of the cell membrane ? |
Lateral movements (rapid)
Flippase and floppase transfer the molecule from one lipid bilayer to another Rotation |
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What are the two types of phospholipids in the cell membrane? |
Phosphoglycerides and sphingomyelins |
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What are the properties of the phospholipids that make them perfect for membranes? |
Emulsify and aggregate Surface active agent Amphipathic |
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What is the most numerous phospholipid in the plasma membrane? |
Phosphoglycerides |
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What are phosphoglycerides comprised of? |
Contain glycerol, fatty acid, phosphate and alcohol |
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What is the simplest form of a phosphoglyceride? |
Phosphatic acid = the precursor for all other phosphoglyceride molecules |
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Examples of phosphoglycerides |
Phosphatidylcholine phosphatidylethanolamine phosphatidylserine phosphatidylinositol phosphatidic acid |
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Components of the sphingolipid |
Sphingosine backbone and fatty acid which makes ceramide |
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Where are sphingolipids found? |
In plants and animals and are common in the nervous system |
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What is the ratio of phospholipid to cholesterol? |
1:1 |
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What is the function of the cholesterol in accordance to one phospholipid? |
They mobilize the first few hydrocarbon groups of the phospholipid molecules - makes the bilayer les deformable and decreases the permeability to just small and water soluble |
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What is a lipid raft? |
Sphingolipid and cholesterol-enriched micro domain in cell membranes |
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What percentage of the outer membrane surface contains lipid rafts? |
20% |
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What is the function of the lipid raft? |
Role in cell singling, in sorting and trafficking through the secretory (exocytosis) and endocytic pathways |
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Why does a membrane not break everytime a human being moves? |
Due to the Self Sealing Capacity - the phospholipids are so fluid that they just move to the hole |
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Why does the flip-flop process take longer? |
You are taking a hydrophilic (polar) head through a hydrophobic area |
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Name all the membrane features |
1. Fluidity - resistance to movement 2. Selective permeability - impermeable to polar substances 3. Self sealing capacity 4. Asymmetry |
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What does asymmetry mean in the cell membrane? |
Bulkier molecules are more often in the inner side of the membrane |
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Where are phospholipids synthesized for the membrane? |
ER |
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What type of cell membrane proteins do you know and what do they do? |
integral/membrane and peripheral |
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What are the features of membrane proteins? |
Most are glycoproteins
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What are the features of peripheral membrane proteins? |
loosely bound - removed easily Found on inner or outer membrane May be attached to cytoskeleton |
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What are the features of integral membrane proteins? |
Tightly bound and are across the fluid matrix of the lipid bilayer Glycosylated More than 50 types |
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What are the functions of Integral membrane proteins? |
Transport proteins Enzymes Receptors proteins with or without enzymes Hold cells together and connect with ECM |
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Functions of peripheral membrane proteins
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Enzymes
Controllers of intracellular functions |
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Examples of Integral Membrane Proteins |
Transport Enzymatic activity Intercellular joining Cell-cell recognition Attachment of cytoskeleton/matrix |
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Functions of glycoconjugates |
Protects the cell membrane from mechanical and chemical damage |
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What is the role of glycoconjugates in cell-cell recognition? |
Role in fertilization Blood clotting Inflammatory response |
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What kind of charge do glycoconjugates carry? |
Negatively charged so they repeal negatively charged objects - attaches to substrate and other cells |
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What is the glycocalyx |
Network of polysaccharides that project from the cell surface a.k.a sugar coat |
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What produced glycocalyx |
Some bacteria, epithelia, and other cells |
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What are some examples of glycocalyx? |
Outer membranes platelets - fluffy coat Help bacteria from phagocytosis - biofilm in teeth Appears on the cells lining blood vessels Apical portion of microvilli |
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What is the biofilm on teeth considered? |
Glycocalyx |
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What is the glycocalyx made of? |
Rich in glycosidic compounds such as proteoglycans and glycoproteins Contain oligosaccharide chains, glycans, covalently attached to polypeptide side chains |
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What are cell junctions? |
The extracellular side of cells connecting or being side by side |
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What are the five most common cell junctions? |
1. Gap 2. Tight 3. Desmosomes 4. Hemidesmosomes 5. adherens |
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What are microvilli? |
Specializations of the plasmembrane that contain actin filaments |
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What is another form of membrane specialization and where is it found? |
Cristae in the mitochondria |
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What type of cell junction do neutron cells have? |
Gap junctions |
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What type of cell junction do epithelia cells have? |
Desmosomes |
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What are examples of membrane special features? |
Burst border apical surface of epithelial cells Sensory cells in inner ear (stereo cilia) , taste buds, olfactory receptors Plasma surface oocyte, WBC's |
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Tight Junctions other name |
Ztnula Occludens |
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Tight junctions are what type of junctional complex? |
Closely associated areas of 2 cells whose membranes join together |
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Functions of tight junctions |
Hold cells together Prevent passage of molecules and ions though space Preserve transcellular transport Block movement of integral proteins between apical and basolateral surface of the cell |
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Examples of cells with tight junctions |
epithelia cells, stomach cells, intestines, urinary bladder - anywhere that prevents passage of fluid and enzymes. |
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Desmosomes other name |
Macula adherens |
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Desmosomes are what type of junctional complex? |
Cell adhesion proteins Button like welds joining opposing cell membranes Link the proteins that attach the cell surface adhesion proteins to intracellular keratin cytoskeleton filaments |
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Functions of the desmosomes |
Resist shearing forces Gives strength and rigidity |
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Desmosomes are found in what cells? |
Epidermis, cardiac muscles cells |
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Gap Junctions other name |
nexus |
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Gap junctions are what type of junctional complex? |
Specialized intercellular connect between cell types Junctions provide direct connection ( doors) between cells Allows molecules and ions to travel freely between cells |
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What do gap junctions play a large role in? |
Form electrical impulses Direct transmission of action potentials without transmitter, receptor etc. |
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Where are gap junctions found ? |
Lens, cornea of eye |
