Cell membrane transport Flashcards
The Cell Membrane, Also Called The Plasma Membrane Or Plasmalemma
Is A Complex Structure With Many Functions
The Cell Membrane Performs Many Biological Functions
Import & Export Of All Required Substances
●Cell Signaling (Receptors)
●Cell To Cell Recognition & Cell To Cell Interactions
●Cell To Cell Binding & Cell To Extracellular Matrix Binding
●Maintains A Voltage (Electrical Charge Difference) In All Living Cells
The Cell Membrane Requires Many Types Of Proteins To
Perform Its Impressive Range Of Biological Functions
The Cell Must Maintain, Adjust The Size, And?
Frequently Repair The Cell Membrane
The Endoplasmic Reticulum (ER) & Golgi Apparatus Possess The?
Enzymes To Synthesize The Phospholipids & Steroids Like Cholesterol That Form Human Cell Membranes
The Cell Must Precisely Control The Flow Of An Enormous Range Of Materials Across The Cell Membrane To Exist As Coherent, Functional, Biological System
●This Requires Many Types Of Transport Mechanisms
The Variety Of Substances That Must Cross The Cell Membrane Differ In?
Size, Shape, And Chemical Properties
The Electrically Neutral Characteristic Of Small Hydrophobic & Nonpolar Molecules Enables Them To?
Pass Directly Through The Hydrophobic Interior Of The Cell Membrane
Diffusion
Supplies The Energy That Drives Their Transport Across The Cell Membrane
Many Small, Polar, Hydrophilic Atoms & Molecules Must Cross The
Cell Membrane To Maintain Cell Function
Their Chemical Characteristics Prevent Them From
Directly Passing Through The Hydrophobic Interior Of The Cell Membrane
The Facilitated Diffusion Of Small Hydrophilic Ions (Ca++) And Water (H2O) Molecules Requires Membrane Transport Proteins
Called Channel Proteins
The Channel Proteins Embedded In The Membrane Have A Hollow Interior (Channel)
The Small Size Of Ions (Ca++, Na+) And H2O Molecules Enables Them To Pass Through The Channel
*The Diameter Of The Channel Is Larger Than The Diameter Of The Ions And H2O Molecules
*Millions Of Ions (Ca++, K+) Or H2O Molecules Pass Through A Single Channel Protein Per Second
●The Cell Membrane Contains > 300 Types Of Channel Proteins
Carrier Proteins Enable The Facilitated Diffusion Of Small Hydrophilic Molecules, Except For H2O, Across The Cell Membrane
The Diameter Of These Molecules Is Too Large To Pass Through The Channel Proteins
*They Require The Carrier Proteins To “Carry” Them Across The Cell Membrane
*Each Carrier Protein Transports ~100 - 1000 Molecules Per Second
All Cells Use Active Transport, Which Requires Chemical Energy, To Move Small Hydrophilic Ions. Molecules
Across The?
Cell Membrane From Lower To Higher Concentration
Some Cancer Cells Are Drug-Resistant Due To Drug Export
Some Antibiotic-Resistant Pathogenic Bacteria Use Multi-Drug Resistance Proteins To Export Antibiotic Molecules
The Cell Membrane Functions
Some Proteins are embedded in the lipid bilayer, and other Proteins are attached to the surface of the membrane
●The variety of Proteins associated with the cell membrane includes the -
*Receptor proteins that recognize signals
*Proteins that connect the receptors to the proper signal transduction pathway
*Transport proteins that move hydrophilic substances across the cell membrane
*Proteins that enable cells to bind to other cells
*Proteins that attach cells to the extracellular matrix that exists between the cells
*Glycoproteins that enable cells to recognize other cells
oThe Glycoproteins have one or more oligosaccharides attached to specific amino acids
*Enzymes like Lactase that convert the disaccharide lactose into glucose and galactose
*Proteins that enable vesicles to fuse with the cell membrane to adjust its size and content
oThese proteins enable vesicles to discharge the secretory proteins they contain into the ECF
*Proteins that enable the cell membrane of our white blood cells to surround and engulf a variety of foreign invaders like viruses, the spores of pathogenic fungi, and pathogenic bacteria
These Basic Chemical Concepts To Facilitate Your Comprehension Of Cell Membrane Transport
An Element is a pure chemical substance consisting of one type of Atom
●The Atom is the basic unit of a chemical element
●A Molecule is a chemical consisting of two or more Atoms
●A Compound is a molecule consisting of two or more types of Elements
●An Ion is an electrically charged particle
*Ions can be charged elements like Sodium (Na+) or Chloride (Cl-) or charged molecules like the Amino Acids
●A Polar substance has an unequal electrical charge distribution and can form Hydrogen Bonds with Water (H2O) Molecules
*Polar substances cannot interact with Hydrophobic Lipid Molecules
●Hydrophobic & Nonpolar substances have an equal distribution of Electrons and consequently do not have electrical charges on their surface
*They are Electrically Neutral
*Hydrophobic substances cannot form temporary Hydrogen Bonds with H2O molecules and consequently are Insoluble in aqueous solutions
