Properties of Cell Membranes Flashcards
___ Are Mosaics
Membranes
Eukaryotic Membranes Contain
- Lipid bilayer matric: Hydrophobic!
- Intrinsic and Extrinsic Proteins
- Glycolipids and Glycoproteins
Function of Membrane
- Serve as reactive surface
- Serve to compartmentalize the cell
- Serve to control entry and exit of molecules
Peripheral Proteins are noncovalently bonded to…
Integral Proteins
Most integral membrane proteins have membrane-spanning alpha-helical domains of about __ amino acids
20
Some integral proteins have multiple…
membrane-spanning domains
Some proteins are linked to membrane phospholipids via…
an oligosaccharide
2 main types of entry and exit mechanisms
Passive and Active
Passive diffusion is a critical mechanism to move molecules…
into and out of the cell
Write out FICK’s law for movement of a solute through a solution only
Ji=DiA(C1-C2)/x
J=Molar Flux of i (mol/cm^2-sec) D= Diffusion coefficient of i A=Area over which diffusion takes place (C1-C2)= Concentration gradient x=distance over which diffusion takes place
Main movement through the membrane
- Unidirectional flux in, minus flux out
- Pore (non-gated channel)
- Channel (gated pore)
___ can be active or passive
Carrier Mediated Transports
The flux of transporter proteins reach a __-
Maximum Level (JMax)
Example of Active Transport
Na/K Pump
3 Na+ Out for 2 K+ In
-Pump is electrogenic
Michaelis-Menten Kinetics
Km
Jmax (Vmax)
Name an example of a cell with multiple transport mechanisms whose function is to pass nutrients from the lumen of the gut to the blood.
The gut epithelial cell
What happens in gut upon eating a meal?
Upon eating a meal: Na and
glucose concentrations
increase in gut.
The serotonin transporter is an example of
of a protein with facilitated diffusion properties whose function is to clear neurotransmitter from the synaptic cleft of brain cells.
____are a special type of transport mechanism - with characteristics of both passive diffusion and carrier mediated diffusion.
Ion Channels
Ion channels demonstrate…
selectivity based
on the size of the channel opening
Types of channels include…
Voltage gated Ligand gated Pressure/stretch gated Non-gated (passive leak) Water channel (aquaporins)
Ion Channel Structure
- 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.
What is Patch Clamp
recording technique for a single channel
Flux and Direction is determined by…
Driving Force (voltage)
What is resting membrane potential?
(dynamic balance between K and Na leakage )
what happens when membrane potential is- More positive/ More negative
Depolarized/hyperpolarized
