Module 1: Background slides Flashcards
What are the two main roles of a membrane?
Isolate cells from their environment
Organize intracellular pathways into subcellular compartments
What are the two main types of membrane proteins?
Integral membrane proteins
and
Peripheral membrane proteins
Define integral membrane proteins
- Tightly bound to membrane
2. Embedded in bilayer OR go all the way through
Define peripheral membrane proteins
- Weaker association with the lipid bilayer
2. May be held by glycolipid anchor to membrane
What are the three main types of membrane transport
- Passive diffusion
- Facilitated diffusion
- Active transport
What types of molecules can utilize passive diffusion?
Lipid-soluble molecules
What types of molecules can utilize facilitated diffusion?
Hydrophillic molecules
What are two things required for facilitated diffusion?
- Concentration gradient
2. Protein transporter
What are the three types of proteins used in facilitated diffusion?
a. Ion channels
b. Permeases
c. Porins: used for larger molecules
What are the two types of active transport?
Primary and secondary active transport
Define primary active transport
ATP is used to drive an ion up its conc. Gradient
Define secondary active transport
Use of another molecules conc gradient to go against its own
What are three ways to distinguish between types of transport across the membrane?
i. Direction of transport
ii. Nature of carriers
iii. The role of energy
What are the three types of ion channels
Voltage gated
Ligand gated
Mechanically gated
What are two factors that guide selectivity of ion channels?
i. Ion-selective binding sites
ii. Conformational changes
What role does the Na+/K+ ATPase play?
Transports 3 Na+ out of the cell while shunting 2 K+ into the cell using the power of ATP
What two uses does a membrane potential play for a cell?
Provides cell with energy for cell-cell communication and membrane transport
How significant is ion movement during (de)polarization events?
a. In general small numbers of ions move in and out of the cell during hyper- and depolarization
b. Therefore, no significant effect on ion conc. in the short term
What is Ohms Law?
V=IR
Define current clamp recording
Membrane potential is free to vary, but can be influenced by applying current
Define voltage clamp recording
a. Membrane potential is held constant by applying current through an electrode
What are the three types of electrodes present in voltage clamp recording?
i. Reference (ground electrode)
ii. Clamp electrode (injects current)
iii. Sensing electrode (sensing voltage in the neuron
Define single channel recording - patch clamp
a. A glass pipette is fused to a tiny region of the membrane
b. The pipette is used as an electrode to record currents flowing through one of several individual channel proteins
Whcih portion of the voltage-gated Na+ channels is responsible for sensing voltage and moving toward the extracellular surface of the cell, causing the channel to change conformation?
S4 domain
