cell Membrane/Introduction to Electrophysiology Flashcards
Eukaryotic membranes contain?
Lipid bilayer matrix: Hydrophobic!
Intrinsic and extrinsic proteins
Glycolipids and glycoproteins
What are the functions of Eukaryotic membranes
Serve as a reactive surface
serve to compartmentalize the cell
Serve to control entry and exit of molecules
Is the peripheral protein located in the Intracellular or the extracellular space?
Extracellular space and intracellular space, but on one side
what bond exist btwn the peripheral and integral protein
They are non-covalently bonded
Integral proteins are linked to phospholipids Via?
Oligosaccharides or directly to fatty acids
Factors which determine the rate of movement during passive diffusion are
area, concentrations, and distance of diffusion
What are pores
A non-gated conduit/Channel that is always open
What are channels
These are conduits that are gated by a door and open and close periodically
FYI about the gut and transport mechanism
The gut epithelial cell is an example of a cell with multiple transport mechanisms whose function is to pass nutrients from the lumen of the gut to the blood
Ion channels demonstrate selectivity based on the size of the channel opening Types T/F?
True
Types of channels
Voltage-gated •Ligand-gated •Pressure/stretch gated •Non-gated (passive leak) •Water channel (aquaporins)
What are the components of each subunit voltage-gated channel
Six transmembrane Helices
What are ion channels made up of
The ion channel structure is derived from the primary amino acid sequence. It consists of multiple subunits, each with distinct trans-membrane segments (domains) that fulfill distinct roles. also areoligomeric complexes that compose of multiple subunits
Tetramer
Voltage gated ca+,K+,Na+ channels. This is a ca+ release release channel.
Pentamer
Nicotine Ach receptor channel
Hexamer
Half gap junction channel or connexon, made up of 6 connexins.
Ionic flux and direction is determined by?
Driving force(Voltage)
what dictates the direction of ion flux, the sign of the membrane potential and the value of the membrane potential
Ion concentration gradient
What is the Nernst Equation used for
Use for determination of equilibrium potentials for any ion (Eeq)
What is the Goldman-Hodgkin-Katz equation
Use for determination of Membrane Potentials of cells(Vm) (multiple ions)
When are membrane potentials generated
During passive diffusion through channels
What determines the permeability of the cell during an influx
Cross-sectional area, diffusion coefficient, membrane Thickness
What are the things that can cotransport with Sodium into the cells
Glucose and Amino Acids Can Be Transported into Most Cells through Sodium Co-Transport. The transport carrier protein has two binding sites on its exterior side—one for sodium and one for glucose or amino acids. Again, the concentration of sodium ions is very high on the outside and very low on the inside, providing the energy for the transport. A special property of the transport protein is that the conformational change to allow sodium movement to the cell interior does not occur until a glucose or amino acid molecule also attaches.
Which substances are counter-transported out of the cells through sodium counter transport mechanism
Calcium and Hydrogen Ions Can Be Transported out of Cells through the Sodium Counter-Transport Mechanism
XX Calcium counter-transport occurs in most cell membranes, with sodium ions moving to the cell interior and calcium ions moving to the exterior, both bound to the same transport protein in a counter-transport mode.
• Hydrogen counter-transport occurs especially in the proximal tubules of the kidneys, where sodium ions move from the lumen of the tubule to the interior of the tubular cells, and hydrogen ions are counter transported into the lumen.