Term
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Definition
The fluid-mosiac model of membrance structure consists of a fluid phospholipid bilayer in which embedded proteins form a mosiac pattern.
(84) |
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Term
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Definition
Phospholipid is a molecule that has both a hydropholic (water-loving) region and a hydrophobic (water-fearing) region.
(85) |
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Term
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Definition
Cholesterol is another lipid that is found in animal plasma membrane.
(85) |
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Term
| Glocolipids & Glycoproteins |
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Definition
both phospholipids and proteins can have attached carbohydrates (sugar) chains, if so theses molecules are called glocolipids & glycoproteins.
(86) |
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Term
| Fluidity if Plasma Membrane |
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Definition
The fluidity of the membrane, which is dependent on its lipid component, is critical to its proper functioning.
(86) |
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Term
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Definition
Allows a particular molecule or ion to cross the plasma membrane freely.
(87) |
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Term
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Definition
Selectively interacts with a specific molecule or ion so that it can cross the plasma membrane.
(87) |
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Term
| Cell Recognition Proteins |
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Definition
The MHC (major histocompatibility complex) glycoproteins are different for each person, so organ transplants are difficult to achieve.
(87) |
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Term
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Definition
is shaped a way that a specific molecule can bind to it.
(87) |
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Term
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Definition
Catalyzes a specific reaction.
(87) |
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Term
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Definition
regulates the passage of molecules into and out of the cell.
(88) |
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Term
| Differentially (selectively) Permeable |
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Definition
meaning that certain substances can move across the membrane while others cannot.
(88) |
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Term
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Definition
Molecules that from an area where their concentration is high to an area where their concentration is low.
(88) |
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Term
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Definition
Plasma Membrane is differentially permeable. Certain substances can freely pass through the membrane, and others cannot. Those that cannot freely cross the membrane may be transported across either bu carrier proteins or by vesicle formation.
(88) |
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Term
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Definition
Diffusion is the movement of molecules from a higher to a lower concentration, it is spontaneous and no chemical energy is required to bring it about.
(89) |
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Term
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Definition
Molecules difuse down their concentration gradients. A few types of small molecules can simply diffuse through the plasma membrane.
(89) |
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Term
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Definition
The diffusion of water across a differentially (selectively) permeable membrane due to concentration differences is called Osmosis.
(90) |
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Term
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Definition
| Osmotic Pressure is the pressure that developes ina system due to osmosis. |
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Term
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Definition
Solutions that cause cells to swell, or even to burst, due to an intake of water are said to be hyphotonic solutions. (lower solutes)
(90) |
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Term
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Definition
the solute concentration and the water concentration both inside and outside the cell are equal. (same)
iso = "the same as" & tonicity = strength of the solution.
(90) |
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Term
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Definition
the swelling of a plant cell in a hypotonic solution creates turgor pressure.
(91) |
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Term
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Definition
Solutions that cause cells to shrink or shrivel due to loss of water are said to be hypertonic solutions. (higher solutes)
(91) |
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Term
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Definition
Any concentration of salt soolution higher than 0.9% is hypertonic to red blood cells...the term crenation refers to RBC in this condition.
(91) |
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Term
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Definition
| Plasmolysis is a shrinking of the cytoplasm due to osmosis. |
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Term
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Definition
In a hypertonic solution, a cell neither gains nore loses water.
(91) |
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Term
| Hypotonic & Hypertonic Solutions |
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Definition
In a "hypotonic solution", a cell gains water & in a "hypertonic solution", a cell loses water and the cytoplasm shrinks.
(91) |
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Term
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Definition
some of the proteins in the plasma membrane are carriers. The transport biologically useful molecules into and out of the cell.
(92) |
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Term
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Definition
Facilitated transport explains the passage of such molecules as glucose and amino acids across the plasma membrane even though the are not lipid-soluble.
(92) |
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Term
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Definition
During an Active Transport, molecules or ions move through the plasma membrane, accumulating either inside or outside the cell.
(92) |
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Term
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Definition
Proteins involved in active transport often are called pumps.
(92) |
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Term
| Concentration Gradient (2) |
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Definition
During facilitated transport, small molecules follow their concentration gradient. During active transport, small molecules and ions move against their concentration gradient.
(93) |
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Term
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Definition
During exocytosis, a vesicle fuses with the plasma membrane as secretion occurs. Exocytosis deposits substances on the outside of the cell and allows secretion to occur.
(94) |
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Term
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Definition
During endocytosis, cells take in substances by vesicle formation.
(94) |
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Term
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Definition
| When the material taken in by endocytosis is large, such as a food particle or another cell, the process is called phagocytosis. |
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Term
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Definition
Pinocytosis (Gk.pinein, to drink) when vesicles form around a liquid or around very small particles.
(94) |
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Term
| Receptor-Mediated Endocytosis |
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Definition
Receptor-Mediated Endocytosis is a form of pinocytosis that is quite specific because it uses a receptorr protein shaped in such a way that a specific molecule such as a vitamin, peptide hormone, or lipoprotein can bind to it.
(94) |
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Term
| Exocytosis, Endocytosis, & Receptor-Mediated Endocytosis (Summary) |
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Definition
Substances are secreted from a cell by exocytosis. Substances enter a cell by endocytosis. Receptor-mediated endocytosis allows cells to take up specific kinds of molecules and then they are released within the cell.
(95) |
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Term
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Definition
Anchoring Junctions serve to mechanically attach adjacent cells.
(96) |
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Term
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Definition
In adhesion junctions, internal cytoplasmic plaques, firmly attached to the cytoskeleton within each cell, are joined by intercellular filaments.
(96) |
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Term
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Definition
At a desmosome, a single point of attachment between adjacent cells connects the cytoskeletons of adjecent cells. Desmosomes are the most common type of intercellular junction between skin cells.
(96) |
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Term
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Definition
Adjecent cells are even more closely joined by tight junctions, in which plasma membrane proteins actually attach to each other, producing a zipperlike fastening.
(96) |
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Term
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Definition
A gap junction allows cells to communicate. A gap juction is formed when two identical plasma membrane channels join.
(96) |
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Term
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Definition
An extracellular matrix is a nonliving meshwork of polysacharides and proteins in close association with the cell that produced them.
(96) |
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Term
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Definition
In addition to a plasma membrane, plant cells are surrounded by a porous cell wall that varies in thickness, depending on the function of the cell.
(97) |
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Term
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Definition
In a plant, the cytoplasm of living cells is connected by plasmodesmata, numerous narrow, membrane-lined channels that oass through the cell wall.
(97) |
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