CELL MEMBRANE TRANSPORT
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The cell membrane enables
Life to exist
Components of the cell membrane
-Phospholipids -Steroids (cholesterol) -Extrinsic membrane proteins -Intrinsic membrane proteins
Cell membrane functions
-Import and export of all required substances -Cell signaling -Cell to cell recognition/interactions -Maintains a voltage in cells -Cell to cell binding and cell to extracellular matrix binding
The ER and golgi apparatus
Possess enzymes that synthesize phospholipids and steroids that form cell membranes
The golgi apparatus uses
Vesicles to deliver new membrane materials to the cell membrane
Vesicles fuse with the
Cell membrane to increase its size
The _______ neutrality of small hydrophobic and nonpolar molecules enables them to pass directly through the hydrophobic interior of the cell membrane
Electric
_______ supplies the energy that drives their transport
Diffusion
Many small, polar, hydrophilic atoms and molecules must cross the ____ _________ to maintain cell function
Cell membrane
What small, polar, hydrophilic atoms and molecules must cross the cell membrane to maintain cell function?
-Electrically charged ions (Calcium, Chloride) -Water molecules -Glucose, amino acids, nucleotides -Their hydrophilic properties prevent their direct passage through the hydrophobic interior of the cell membrane
The facilitated diffusion of small hydrophilic ions and water molecules requires
Channel proteins
Channel proteins in the cell membrane have a
Hollow interior (channel) Channel diameter is larger than ion and H20 diameter
The cell membrane contains
> 300 types of channel proteins
________ enable H20 molecules to cross cell membranes
Aquaporins (water porous)
Channel proteins _______ the diffusion
Facilitate
________ proteins enable the facilitated diffusion of small hydrophilic molecules, except for H20, across the cell membrane
Carrier
These molecules are too large to pass through _______ proteins
Channel -They require carrier proteins to “carry” them across the membrane
Each carrier protein transports
~100-1000 molecules per second
Active transport
Requires chemical energy Move small hydrophilic atoms and small molecules across the cell membrane from lower to higher concentration
Active transport proteins
Carrier proteins or ion pumps
Some cancer cells are drug resistant due to
Drug export
The function of mutli-drug resistance proteins is to
Export potentially toxic molecules before they harm the cell
Multi-drug resistance proteins also enable
-Cancer cells to export cancer drugs -Antibiotic resistant pathogenic bacteria to export antibiotic molecules