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Definition
| The dual layer of phospholipids that make up the cell membrane. The fatty acid tails point in towards each other creating a hydrophobic middles section. |
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Term
| Integral Membrane Proteins |
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Definition
Proteins found within the phospholipid bilayer membrane. They have hydrophobic amino acid side groups imbedded in the membrane, in contact with the hydrophobic tails of the phospholipids.
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Term
| Peripheral Membrane proteins |
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Definition
Proteins more loosely bound to the membranes. Some are linked to the cytoskeletal components inside the cell |
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Definition
Lipids within a layer may move rapidly by one another unless held in place. Proteins may also move within the plane of the membrane. The phospholipids cannot flip flop from one layer to the other withou help of some sort. |
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Definition
| The net movement of materials across membranes that does not require any special source of energy. |
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Definition
The simplest form of passive transport, the net movement of molecules down their concentration or chemical gradient from high to low concentration. The trend is to make the concentrations more equal |
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Definition
| When a membrane is not permeable to glucose, but is permeable to water then water will move down its concentration gradient with a net flow or flux from high concentration area to low concentration area |
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Definition
| The pressure created by the difference in concentration of water. |
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Definition
| When the solution has a concentration of particles that is greater than that on the other side of the membrane. |
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Definition
| When the concentrations are equal on both sides of the membrane. |
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Definition
When ions diffuse from one side to another and a charge difference develops When this occurs along with the chemical gradient it is known as an electrochemical gradient. At equilibriumEk=(RT/zF)In([K2]/[K1]) E is potential (voltage) across the membrane R & F are constants T is absolute temp in kelvin z is the charge on potassium and [] indicates concentration
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Term
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Definition
carrier mediated, membrane proteins help other molecules to cross the membrane. This movement is both ways and is passive, molecules that exhibit facilitated diffusion run down their concentration gradients only. This is a way of getting particular hydrophilic molecules across membranes.
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Term
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Definition
the movement of materials across membranes that requires a source of energy. Sources - ATP hydrolysis
- preexisting concentration gradient for an ion
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Term
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Definition
a large membrane protein responsible for pumping both Na+ and K+ up their concentration gradients. Uses energy from the hydrolysis of ATP Cycle: - three Na ions from inside the cell bind to the pump protein
- ATP is hydrolyzed with the phosphate group binding to the pump protein
- pump protein changes conformation
- Three Na+ ions are released outside of cell
- two K+ ions from outside the cell bind to the pump protein
- phosphate group is released from poump protein
- pump protein is restored to the original conformation
- K+ ions are released into cell
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Term
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Definition
An active transport mechanism The energy in an existing gradient of ions is used to pump another ion or molecule up its concentration gradient. This is achieved by allowing the sodium ions to move down their concentration gradient at the same time as the other ion or molecule is moving up its gradient. Special membrane proteins couple these two processes. |
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Term
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Definition
a membrane bound package (granule or vesicle) fuses its membrane with the outer membrane of the cell, allowing the material in the package to pass to the outside of the cell.
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Term
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Definition
Material on the outside of the cell is engulfed by an infolding of part of the cell memrane as a consequence a membrane bound package filled with material from outside of the cell is formed inside the cell. Three Forms - phagocytosis
- pinocytosis
- receptor mediated endocytosis
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Term
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Definition
In a eukaryotic cell this is a large spherical body bounded by a anuclear envelope. Traffic into and out of the nucleus passes through specialized pores in the nuclear envelope. The pores are complex protein containing structures that are selective (only allow certain materials to pass).
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Definition
Found inside of the nucleus (the "stuff" of chromosomes). These condense during cell division. These contain DNA, Histones (structural proteins) and other proteins involved in duplication and repair.
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Definition
| Specialized region within the nucleus where ribosomes are assembled. |
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Term
| Endoplasmic reticulum (ER) |
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Definition
A maze of membrane-bound compartments. Two Types - Rough
- Smooth
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Definition
It is rough due to the presence of ribosomes bound to the surface. Proteins being made on the ribosomes aon the rough ER are inserted into the lumen (interior) of the ER through channels in the ER membrane. |
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Term
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Definition
The inserted proteins include membrane proteins and secretory proteins (secreted from the cell) These proteins have been targeted to the rough ER by their first 30-40 amino acids. After they enter the ER these signal sequences are usuall removed and Carbohydrate groups are added to some by enzyemes within the ER Lumen.
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Term
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Definition
| Begins in the rough ER and continues in the smooth ER. The membrane and secretory proteins move through the rough ER lumen which is continuous with the lumen of the smooth ER. The smooth ER contains enzymes that then catalyze the construction of membrane phospholipids and shift them from one side of the lipid bilayer to the other. |
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Definition
No bumps (ribosomes) on it. Catalyzes the construction of membrane phospholipids. Shift phospholipids from one side of the lipid bilayer to the other. |
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Definition
A stack of membrane bound sacs that serves as a sorting mechanism for all the components of membranes and other lumen contents from the rough and smooth ER. Also servves to refine some of the carbohydrates attached to the proteins and recycles materials back to the ER. The materials are moved through the GA by Transition vesicles. |
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Definition
| Bud from the smooth ER and carry materials to one side of the Golgi apparatus (where they are then sorted, recycled etc.). |
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