Term
| What is the fluid mosaic model of the plasma membrane? |
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Definition
fluid - allows things to move in and out
mosaic - different types of substances embedded in the membrane |
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Term
| Why are lipids used in the plasma membrane? |
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Definition
| they are usually nonpolar and are arranged so that the hydrophilic side faces the aqueous environment and the hydrophobic region is interior; this allows you to create barriers between the insides and outsides of cell; it's functional and doesn't require a lot of energy |
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Term
| What is significant about the phospholipid? |
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Definition
| primarily makes up the lipid bilayer; the phosphate groups face the cytosol and extracellular fluids (polar side) while the fatty acid tails face inside the lipid bilayer (nonpolar) |
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Term
| What is the significance of cholesterol? |
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Definition
| it is flat, plane, 3D structure; works very well to be inserted into the plasma membrane because it "stiffens" the plasma membrane |
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Term
| What is an integral protein? |
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Definition
| a protein embedded in the membrane that often functions as a channel between the inside and outside of cell |
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Term
| What is a peripheral protein? |
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Definition
| protein that rests on either the interior or exterior surface of the plasma membrane; doesn't go across the membrane and functions as receptors or enzymes |
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Term
| What is the function of the membrane dependent on? |
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Definition
| the proteins -> the proteins confer most of the function of the plasma membrane |
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Term
| Where are carbohydrate (CHO) attachments usually found? |
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Definition
| the external surface of the membrane |
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Term
| What are the two types of carbohydrates found on the plasma membrane? |
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Definition
-glycolipids
-glycoproteins |
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Term
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Definition
| a carbohydrate attached to a lipid |
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Term
|
Definition
| a carbohydrate attached to a protein |
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Term
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Definition
| special concentrations of sphingolipids and cholesterol found in about 20% of the outer membrane |
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Term
| What are lipid rafts used for? |
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Definition
| cell signalling and possibly cell invagination |
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Term
| What are specialized membrane structures? |
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Definition
-microvilli
-membrane-membrane adhesions
-membrane junctions |
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Term
|
Definition
| folds of plasma membrane that increase the surface area |
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Term
| What is microvilli important for? |
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Definition
| important in absorptive cells because the increase in surface are allows more nutrients to be absorbed |
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Term
| How are microvilli held in place? |
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Definition
| actin cores - a microfilament cytoskeletal element that helps keep the microvilli's integrity constant so absorption can continue |
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Term
| What are the two types of membrane-membrane adhesions? |
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Definition
-glycocalyx
-wavy contours |
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Term
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Definition
| membrane-membrane adhesion in which the glycoproteins and glycolipids are able to interact with sugars of a neighboring cell |
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Term
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Definition
| membrane-membrane adhesion in which plasma membranes have a waviness to them that complements the waviness of the call adjacent to it |
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Term
| What are the different types of membrane junctions? |
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Definition
-tight junction
-desmosome
-gap junction |
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Term
| What is a tight junction? |
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Definition
| fused protein molecules in adjacent membranes that are very protective and prevent material from coming between cells and entering the blood stream |
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Term
| Where are tight junctions often found? |
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Definition
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Term
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Definition
| consists of linker proteins and keratin filaments that provide integrity to tissues by holding adjacent cells together; it resists torsion |
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Term
| Where are desmosomes often found? |
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Definition
| cells that undergo a lot of torsion --> epidermis and uterus |
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Term
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Definition
| proteins that form hollow passageways between cells and allow material to flow between cells, usually ions; allows for quick communication between cells and action potential propogation |
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Term
| Where are gap junctions often found? |
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Definition
| in cardiac tissue and smooth muscle |
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Term
| What are the functions of the plasma membrane? |
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Definition
-transport processes
-cell to cell adhesion to form tissues
-communication between one cell to another and cell to environment |
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Term
| What are the different types of transport processes? |
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Definition
-passive transport
-active transport |
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Term
| What is passive transport? |
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Definition
| no energy is needed to be added to a system in order to transport something; it'll happen on its own |
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Term
| What are the different types of passive transport? |
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Definition
-simple diffusion
-osmosis
-facilitated diffusion
-filtration
-pressure changes
-cellular tonicity changes |
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Term
| What is simple diffusion? |
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Definition
| due to the tendency of all molecules to randomize, substances will move from an area of high concentration to low concentration across a membrane |
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Term
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Definition
| the diffusion of water molecules from an area of high concentration to low concentration |
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|
Term
|
Definition
| the number of particles/liter |
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Term
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Definition
| the number of particles/kg |
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Term
| What is facilitated diffusion? |
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Definition
| involves the presence of protein to make it easier for the molecules to be transported across |
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Term
| What two types of proteins can facilitate diffusion have? |
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Definition
carrier-mediated proteins
channel-mediated proteins |
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Term
| What is a carrier-mediated protein? |
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Definition
| protein that allows the substance to pass through by remaining closed on one side and open on other. molecule goes to the middle, open side closes and the closed side opens, allowing it through |
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Term
| What is a channel-mediated protein? |
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Definition
| protein that allows the substance to pass through; channel that is open on either side |
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Term
|
Definition
| water and solutes are pushed through membranes along a pressure gradient from high pressure to low pressure |
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Term
| What are the types of pressure changes that affect passive diffusion? |
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Definition
| the osmotic pressure and hydrostatic pressure |
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Term
| What is osmotic pressure? |
|
Definition
| pressure that resists further water entry into a chamber due to osmosis |
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|
Term
| What is hydrostatic pressure? |
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Definition
| pressure that is exerted by the fluid on the wall of the chamber that encloses it |
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Term
| What are cellular tonicity changes? |
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Definition
| the ability of a solution to change the shape, or tone, of cells by altering the cell's internal volume |
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Term
| What are the three types of cellular tonicity changes? |
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Definition
| isotonic, hypotonic, hypertonic |
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Term
| What is an isotonic solution? |
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Definition
| the concentration of materials is the same as outside of the cell --> no net movement of water |
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Term
| What is a hypotonic solution? |
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Definition
| the solution surrounding the cell is less concentrated than the inside of the cell --> water moves from outside into the cell |
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Term
| What is a hypertonic solution? |
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Definition
| the solution outside the cell is more concentrated than the inside of the cell --> water moves from inside out of the cell |
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Term
| What are the different types of active transport? |
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Definition
-primary active transport
-secondary active transport
-vesicular active transport |
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Term
| What is active transport? |
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Definition
| energy is needed to be added to a system in order to transport something |
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Term
| What is primary active transport? |
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Definition
| ATP is used to move a molecule against its concentration gradient |
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Term
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Definition
| when molecules are actively transported at the same time in the same direction |
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Term
|
Definition
| when molecules are actively transported in opposite directions |
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Term
| What is secondary active transport? |
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Definition
| a concentration gradient that is set up by primarily moving a molecule across the membrane against its gradient; molecules that were originally pushed across membrane are capable of "escorting" a second molecule along its concentration gradient |
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Term
| What is vesicular active transport? |
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Definition
| movement of vesicles to and from a membrane which is taking contents somewhere |
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Term
| What are the types of vesicular active transport? |
|
Definition
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|
Term
|
Definition
| vesicle containing a molecule to be secreted, travels to the plasma membrane where it fuses with specific docking proteins, fusion port is formed, and contents are released outside of cell |
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Term
|
Definition
| something enters the cell membrane via a vesicle |
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Term
| What are the types of endocytosis? |
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Definition
-phagocytosis
-pinocytosis
-receptor-mediated endocytosis |
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|
Term
|
Definition
| plasma membrane engulfs something outside of the cell and brings it in via vesicle transport |
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Term
|
Definition
| absorption of a liquid, often containing a nutrient, brought in via vesicle |
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Term
| What is receptor-mediated endocytosis? |
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Definition
| receptor on plasma membrane binds with molecule and an endocytotic vesicle is brought into the cell containing the molecule; seen often with insulin |
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Term
| What are the different types of cell-cell adhesion and interaction? |
|
Definition
-tight junction
-desmosome
-glycocalyx |
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|
Term
| What is a tight junction? |
|
Definition
| located near the apical region of cell; designing to help prevent invasion of unwanted materials |
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|
Term
|
Definition
| contains keratin filaments which are very tough and helps prevent cells from separating when there is torsion placed on tissue |
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|
Term
|
Definition
| carbohydrate groups on a membrane; VERY weak however does somewhat contribute to keeping cells together |
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|
Term
| -How does the glycocalyx contribute to keeping the cells together? |
|
Definition
-anchoring-adhesion
-migration and signalling - important in embryological development |
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|
Term
|
Definition
| located on the plasma membrane; designed in a certain way with which to bind with a particular type of ligand |
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|
Term
|
Definition
| some kind of substance coming from the environment; could be hormone, neurotransmitter, drug, etc |
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Term
| What happens when a ligand binds with a receptor? |
|
Definition
| changes the metabolic activity of the cell |
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|
Term
| What are the different types of receptors? |
|
Definition
-catalytic protein
-channel-linked receptors
-G-protein linked receptors |
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Term
| Describe catalytic protein. |
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Definition
| often enzymes; binding of the ligand to these proteins will cause the receptor to catalyze a reaction |
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Term
| Describe channel-linked receptors. |
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Definition
| made of integral proteins which open and close in response to a specific signal; can control the entrance/exit of specific substances; often ion channels and ligand is usually a neurotransmitter |
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Term
| Describe G-linked receptors. |
|
Definition
| receptor that utilizes the assistance of a G-protein to effect a signal; causes a cascade of events to cause a final cellular event and involves a second messenger |
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Term
| What are second messengers? |
|
Definition
| pass a message from a membrane protein to an intracellular protein which will execute a "command" from the original ligand |
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