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71 Cards in this Set
- Front
- Back
Plasma Membrane
Fluid Mosaic Model |
Depicts the membrane as a thin structure composed of a bilayer of lipid molecules with protein molecules "plugged into" or dispersed in it. The Proteins, many of which float in the fluid lipid bilayer form a constantly changing mosaic pattern.
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Plasma Membrane
Glycolipids |
Lipids with attached sugar groups
Found: Outer plasma Membrane. 5% of total membrane lipid. |
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Plasma Membrane
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Extent of a cell thereby separating 2 of the body's major fluid compartments: intracellular and extracellular. 5% Glycolipds; 20% cholesterol - stabilize; 20% lipidrafts
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Plasma Membrane
Integral Proteins |
Inserted in the lipid bilayer
Transmembrane proteins that span the entire width of plasma membrane Some are enzymes Involved in transport Have Pores/Carriers Receptors for hormones |
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Plasma Membrane
Peripheral Proteins |
NOT embedded in the lipid
Attached rather loosely only to integral proteins and are easily removed without disrupting the cell. -Support the membrane from the cytoplasmic side -Enzymes/Motor Proteins/Link Cells |
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Plasma Membrane
Glycocalyx |
Fuzzy, sticky, carbohydrate rich area at the cell surface.
Is used to for cell "talking" |
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Plasma Membrane
Membrane Protein Functions |
1. Transport
2. Receptors for signal Transduction 3. Attachment to the cytoskeleton and extracellular matrix 4. Enzymatic Activity 5. Intercellular Joining 6. Cell-Cell Recognition |
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Plasma Membrane
3 Factors to Bind Cells Together |
1. Glycoproteins in the glycocalyx act as an adhesive
2. Wavy contours of the membranes of adjacent cells fit together 3. Special membrane junctions are formed |
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Plasma Membrane
Tight Junctions |
A series of integral protein molecules in the plasma membranes of adjacent cells fuse together, forming an impermeable junction that encircles the cell
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Plasma Membrane
Desmosomes |
Anchoring junctions; mechanical couplings scattered like rivets along the sides of abutting cells that prevent their separation.
Plaque. |
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Plasma Membrane
Gap Junctions |
Nexus, is a communicating junction between cells
-Connexon - hollow cylinders -Present in electrically excitable tissues (heart; smooth muscle) |
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Plasma Membrane
Interstitial Fluid |
A rich nutritious "soup: Contains thousands of ingredients, including amino acids, sugars, fatty acids, vitamins, regulatory substances such as hormones and neurotransmitters, salts, and waste products.
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Plasma Membrane
Selective Permeable Barrier |
Allows some substances to pass while excluding others
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Plasma Membrane
Passive Process |
Substances that cross the membrane without any energy input from the cell.
1. Diffusion (simple and facilitated) 2. Osmosis |
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Plasma Membrane
Active Process |
Cell provides the metabolic energy (ATP) needed to move substances across the membrane.
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Plasma Membrane
DIffusion |
the tendency of molecules or ions to move down their concentration gradient. (higher to lower)
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Plasma Membrane
Factors for the Speed of Diffusion |
1. Molecular Size (smaller the faster)
2. Temperature (warmer the faster) |
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Plasma Membrane
Diffusion will occur if... |
1. Lipid soluble
2. Small enough to pass through membrane channel 3. Assisted by a carrier molecule |
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Plasma Membrane
Simple Diffusion |
Nonpolar and lipid soluble substances diffuse directly though the lipid bilayer.
Ex. Oxygen, Carbon Dioxide, fat soluble vitamins |
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Plasma Membrane
Facilitated Diffusion |
The transported substance either
1. binds to protein carrier in the membrane and is ferried across 2. moves through water filled protein channels |
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Plasma Membrane
Facilitated Diffusion ->Carriers |
Transmembrane integral proteins that show specificity for molecules of a certain polar substance or class of substances that are too large to pass through membrane channels, such as sugar and amino acids
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Plasma Membrane
Facilitated Diffusion -> Channels |
Transmembrane proteins that serve to transport substances, usually ions or water, through aqueous channels from one side of the membrane to the other *Leakage Channels*
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Plasma Membrane
Osmosis |
The diffusion of a solvent, such as water through a selectively permeable membrane
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Plasma Membrane
Osmosis -> Aquaporins |
Water specific channels constructed by transmembrane proteins
Location: Red Blood Cells, Kidney Tubule |
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Plasma Membrane
Osmosis -> Osmolarity |
Total Concentration of all solute particles in a solution
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Plasma Membrane
Osmosis -> Hydrostatic Pressure |
The back pressure exerted by water against the membrane
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Plasma Membrane
Osmosis -> Osmotic Pressure |
The tendency of water to move into the cell by osmosis
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Plasma Membrane
Osmosis -> Tonicity |
The ability of a solution to change the shape or tone of cells by altering their internal water volume
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Plasma Membrane
Osmosis -> Isotonic |
Solutions with the same concentrations of non-penetrating solutes as those found in cells. No net loss or gain of water.
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Plasma Membrane
Osmosis -> Hypertonic |
Solutions with a higher concentration of non-penetrating solutes than seen in the cell
*Cells crenate, or shrink, in hypertonic solutions |
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Plasma Membrane
Osmosis -> Hypotonic |
Solutions that are more dilute (contain a lower concentration of non penetrating solutes) than cells
*Cells lyse, in hypotonic solutions |
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Plasma Membrane
Active Transport |
Requires carrier proteins that combine specifically and reversibly with the transported substances.
1. Primary Active Transport 2. Secondary Active Transport |
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Plasma Membrane
Active Transport -> Symport System |
In secondary active transport, when two transported substances are moved in the same direction
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Plasma Membrane
Active Transport -> Antiport System |
If secondary active transport, transported substances "wave to each other" as they cross the membrane in opposite direction
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Plasma Membrane
Primary Active Transport |
Transport of substances against a concetration (or electrochemical) gradient. Preformed across the plasma membrane by a solute pump, directly using energy of ATP hydrolysis.
Ex. Ions (Na+, K+, H+, CA2+) |
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Plasma Membrane
Secondary Active Transport |
Co-transport of 2 solutes across the membrane. Energy is supplied indirectly by the ion gradient created by primary active transport. Symport or antiporters.
Ex. Amino Acid |
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Plasma Membrane
Vesicular Transport |
Fluids containing large particles and macromolecules are transported across cellular membranes inside membranous sacs called vesicles.
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Plasma Membrane
Vesicular Transport -> Exocytosis |
Vesicular transport processes that eject substances from the cel interior into the extracellular fluids
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Plasma Membrane
Vesicular Transport -> Endocytosis |
Those in which the cell ingests small patches of the plasma membrane and moves substances from the cell exterior to the cell interior
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Plasma Membrane
Vesicular Transport -> Clathrin |
Protein coating found on the cytoplasmic face of the pit
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Plasma Membrane
Vesicular Transport -> Basic steps in Endocytosis and transcytosis |
1. The substance to be taken into the cell by endocytosis membrane called a coated pit, with protein clathin.
2. The vesicle detaches 3. The coat proteins are recycled back to the plasma membrane 4. The uncoated vesicle then typically fuses with a processing and sorting vesicle called an endosome 5. Some membrane components and receptors of the fused vesicle may be recycled back to the plasma membrane in a transport vesicle 6. The contents either a. combine with a lysosome or transports completely across the cell in transytosis |
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Plasma Membrane
Vesicular Transport -> Phagocytosis |
The type of endocytosis in which the cell engulfs some relatively large or solid material such as a clump of bacteria, cell debris, or inanimate particles
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Plasma Membrane
Vesicular Transport -> Phagosome |
When a particle binds to receptors on the cell's surface, cytoplasmic extensions called pseudopods form and flow around the particle and engulf it.
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Plasma Membrane
Vesicular Transport -> Amoeboid Motion |
The flowing of their cytoplasm into temporary pseudopods allows them to creep along
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Plasma Membrane
Vesicular Transport -> Pinocytosis / Fluid Phase Endocytosis |
A bit of infolding plasma membrane (which begins as a clatrin-coated pit) surrounds a very small volume of extracellular fluid containing dissolved molecules.
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Plasma Membrane
Vesicular Transport -> Receptor-mediated endocytosis |
The main mechanism for the specific endocytosis and transcytosis of most macromolecules by body cells, and it is exquisitely selective. Allows cells to concentrate material that is present only in very small amounts in the extracellular fluid.
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Plasma Membrane
Vesicular Transport -> Caveolae |
Tubular or flask shaped inpocketings of the plasma membrane seen in many cell types, are involved in a unique kind of receptor-mediated endocytosis called POTOSIS. Uses caveloin, cage like protein coat.
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Plasma Membrane
Vesicular Transport -> Coatomer-Coated vesicles |
Vesicles pinch off from organelles and travel to other organelles to deliver their cargo. Accounts for nearly all intracellular trafficking between certain organelles.
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Plasma Membrane
Process of Exocytosis |
1. The membrane bound vesicle migrates to the plasma membrane
2. There, proteins at the vesicle surface (vSNAREs) bind with t STAREs (plasma membrane proteins) 3. The vesicle and plasma membrane fuse and a pre opens up 4. Vesicle contents are released to the cell exterior |
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Plasma Membrane
Membrane Potential |
Voltage, across the membrane
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Plasma Membrane
Resting Membrane potential |
typically rages from -50 to -100 mili volts depending on the cell type
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Plasma Membrane
Polaraized |
The inside of the cell is negative compared to its outside. Exists only at the membrane.
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Plasma Membrane
Electrochemical gradients |
the combined difference in concentration and charge; influences the distribution and direction of diffusion of ions
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Plasma Membrane - Interactions
Cell adhesion molecules (CAM) |
1. The molecular "Velcro" that cells use to anchor themselves to molecules in the extracellular space to to each other
2. The "arms" that migrating cells use to haul themselves past one another 3. SOS signals sticking out from the blood vessels lining that rally protective white blood cells to a nearby infected of injured area 4. Mechanical sensorts the respond to local tension at the cell surface by stimulating synthesis and degradation of adhesive membrane junctions 5. Transmitters of intracellular signals that direct cell migration, proliferations and specialization |
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Plasma Membrane - Interactions
Membrane Receptors |
A huge and diverse group of integral proteins and glycoproteins that serve as binding sites
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Plasma Membrane - Interactions
Contact Signaling |
the actual coming together and touching of cells, it is the means by which cells recognize one another
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Plasma Membrane - Interactions
Chemical Signaling |
Signaling chemicals that bind specifically to plasma membrane receptors, called LIGANDS.
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Plasma Membrane - Interactions
Chemical Signaling -> G Protein Linked Recepotrs |
Exert their effect indirectly through a G-Protein, whcih acts as a middleman or relay to activate a membrane bound enzyme or ion channel.
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Plasma Membrane - Interactions
Chemical Signaling -> Second Messengers |
After G Protein activates, second messengers are generated and connect plasma membrane events to the internal metabolic machinery of the cell.
Impt 2nd messengers: Cyclic AMP and ionic calcium activate protein kinase enzymes |
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Plasma Membrane - Interactions
Electrical Signaling |
certain plasma membrane proteins are channel proteins that respond to changes in membrane potential by opening or closing the channel
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Cytoplasm
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the cellular material between the plasma membrane and the nucleus.
3 Major Elements: 1. Cytosol 2. Organelles 3. Inclusions |
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Cytoplasm
Cytosol |
The viscous, semi-transperent fluid in which the other cytoplasmic elements are suspended
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Cytoplasm
Cytoplasmic Organelles |
Metabolic machinery of hte cell
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Cytoplasm
Inclusions |
FUNCTION: Storage for nutrients, wastes, and cell products
STRUCTURE: Varied; includes stored nutrients such as lipid droplets and glycogen granules, protein crystals, pigment and granules |
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Cytoplasmic Organelles
Mitochondria |
FUNCTION: Site of ATP synthesis; powerhouse of the cell
STRUCTURE: Rodlike, double-membrane structures; inner membrane folded into projections called cristae |
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Cytoplasmic Organelles
Rough Endoplasmic Reticulum (Rough ER) |
FUNCTION: Sugar gorups are attached to proteins wihtin the cisternae. Proteins are bound in vesicles for transport to the Golgi Apparatus and other sites. External face synthesizes phospholipids.
STRUCTURE: MEmbrane system enclosed in a cavity, the cisterna, and coiling thought the cytoplasm. Externally studded with ribosomes. |
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Cytoplasmic Organelles
Smooth Endoplasmic Reticulum |
FUNCTIONS: Site of lipid and steroid (cholesterol) synthesis, lipid metabolism, and drug detoxification.
STRUCTURE: membranous system of sacs and tubules; free of ribosomes. |
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Cytoplasmic Organelles
Golgi Apparatus |
FUNCTION: Packages, modifies, and segregates proteins for secretion from the cell, inclusions in lysosomes, and incorporation into the plasma membrane.
STRUCTURE: a stack of smooth membrane sacs and associated vesicles close to the nucleus. |
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Cytoplasmic Organelles
Lysosome |
FUNCTION: Site of intracellular digestion
STRUCTURE: Membranous sacs containing aid hydrolases |
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Cytoplasmic Organelles
Peroxisomes |
FUNCTION: The enzymes detoxify a number of toxic substances. The most important enzyme, catalse, breaks down hydrogen peroxide.
STRUCTURE: Membranous sacs of oxidase enzymes. |
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Cytoplasmic Organelles
Ribosomes |
FUNCTION:The sites of protein synthesis
STRUCTURE: Dense particles consisting of two subunits each composed of ribosomal RNA and protein. Free or attached to rough endoplasmic riticulum. |