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Definition
"limiting membrane" that surrounds the cell
encloses intracellular fluid |
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Definition
"little organs" within the confines of the cell
each organelle performs a specific function contributing to cell survival |
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Definition
consists of all the fluid located within the confines of the cell membrane.
Can be further classified into cytoplasm and cytosol |
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| includes the intracellular fluid that is located outside of the nucleus |
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Definition
| intracellular fluid which includes that portion of the cytoplasm outside of the organelles |
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Definition
selective barrier restricting movement of molecules into and out of the cell
location of receptors which are able to detect signals from other cells
link cells to adjacent cells
anchor cells to the extracellular matrix |
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Term
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Definition
comprised primarily by phospholipids
phospholipids are amphipathic (polar and nonpolar ends)
because of their amphipathic make-up, when grouped together, phospholipids naturally align into a bimolecular layer
the fact that there are no molecular bonds between these molecules results in a membrane with fluidity
cholesterol is also present in the membrane and adds to its fluidity (temperature dependent) |
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Term
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Definition
integral membrane proteins and peripheral membrane proteins
carbohydrates often bind to proteins extending off the surface of the cell. This forms a structure called a glycoprotein, which is important to cell identification and interaction.
fluid mosaic model of the cell membrane--membrane proteins float in a sea of lipids |
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Term
| integral membrane proteins |
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Definition
amphipathic and integrate themselves into the membrane
many are transmembrane proteins that span the entire width of the membrane
suited to function as channels through which materials can be transported (water, ions, chemical signals, etc.) |
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Term
| peripheral membrane proteins |
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Definition
polar molecules and therefore do not integrate into the membrane
polar aspect of these proteins binds to the polar portion of the membrane
most of these are on the cytosolic surface (inside) of the membrane |
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Term
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Definition
desmosomes
tight junctions
gap junctions |
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Term
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Definition
localized connections between adjacent but non-touching cells
anchor cells together
common in tissue that is subject to stretching (i.e. skin, cardiac muscle)
protein fibers connect between cells, holding them firmly together keep the cells from being pulled apart
not occlusive junctions
"spot weld" or "rivet" or "anchoring junction" |
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Term
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Definition
present where two plasma membranes are joined together, thereby sealing off the passageway between adjacent cells.
extends around circumference of a cell (unlike desmosomes)
restrict the uncontrolled movement of substances between cells (paracellular movement) by limiting the movement of hydrophilic substances between cells (lipophilic substances can still diffuse directly through the cell membrane and will not be limited by tight junctions)
most common in cells that line absorptive surfaces, such as are seen in the gastrointestinal tract and kidney. |
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Term
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Definition
"communicating junctions"
comprised of small channels made up of subunits called connexons which connect the cytosol of adjacent cells.
allow passage of small, water-soluble particles to pass between connected cells
important in the conduction of electrical impulses between adjacent cells, as seen in smooth and cardiac muscle
allow movement of other molecules involved with activities other than electrical signaling |
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