CELL MEMBRANES Flashcards
WHAT IS THE COMPOSITION IN WEIGHT OF PROTEINS, LIPIDS AND CARBOHYDRATES IN THE PHOSPHOLIPID BILAYER
PROTEIN: 55%
LIPIDS: 42%
CARBS: 3%
WHAT ARE THE MAIN COMPONENTS OF THE IC AND EC COMPARTMENTS
NA+ K+ CA2+ CL- PHOSPHATE CARBONATE PROTEIN
WHAT IS THE EC CONC OF SODIUM
145MM
WHAT IS THE IC CONC OF SODIUM
15MM
WHAT IS THE EC CONC OF POTASSIUM
5MM
WHAT IS THE IC CONCENTRATION OF POTASSIUM
150MM
WHAT IS THE EC CONCENTRATION OF CALCIUM
1MM
WHAT IN THE IC CONCENTRATION OF CALCIUM
0.0001MM
HOW DO LIPID SOLUBLE MOLECULES MOVE ACROSS THE MEMBRANE
BY DIFFUSION
HOW DO SMALL MOLECULES AND IONS MOVE ACROSS THE MEMBRANE
BY TRANSPORT PROTEINS
HOW DO LARGE MOLECULES MOVE ACROSS THE MEMBRANE
BY ENDOCYTOSIS
WHAT TYPES OF TRANSPORT PROTEINS ARE THERE
- CARRIERS
- PUMPS
- ION CHANNELS
FACTS ABOUT ACTIVE TRANSPORT
- AGAINST OR WITHOUT AND ELECTROCHEMICAL GRADIENT
- REQUIRES HYDROLYSIS OF ATP
- LOW TURNOVER <100 PER SEC
FACTS ABOUT CARRIERS
- PASSIVE
- CONFORMATIONAL CHANGE
- HIGHLY SELECTIVE
- CARRY OUT FACILITATED DIFFUSION
- TURNOVER OF 10^2-10^3
- SATURABLE
FACTS ABOUT CHANNELS
- PASSIVE
- HAVE A PORE
- CAN BE SELECTIVE
- CAN BE GATED
- HIGH TURNOVER 10^6-10^8
CLASSIFICATIONS OF CARRIER
- UNIPORTER
- SYMPORTER (CO)
- ANTIPORTER
WHAT IS THE PATCH CLAMP TECHNIQUE
A METHOD BY NEHR SAKKMAN USED TO DIRECTLY MEASURE ION CHANNEL FUNCTION
WHAT IS THE CELL ATTACHED METHOD
A PATCH CLAMP TECHNIQUE.
THE MEMBRANE FORMS A HIGH RESISTANCE SEAL TO THE PIPETTE TIP (10^-6) WITH A SALT SOLN (KCL) AND MEASURES WITH RESPECT TO A REFERENCE TO SEE INDIVIDUAL ION CHANNELS OPEN AND CLOSE.
WHAT IS THE WHOLE CELL METHOD
IF WE RUPTURE THE MEMBRANE, THE SOLUTION FILLS THE CELL AND WE CAN MEASURE ALL OF THE CHANNELS IN THE CELL BY MEASURING THE CURRENTS AT DIFFERENT POTENTIALS.
HOW CAN WE MEASURE THE TOTAL CURRENT CARRIED BY A POPULATION OF CHANNELS
I= N * PO*G*(VM-EI) N= NO OF CHANNELS PO= OPEN PROBABILITY G= SINGLE CONDUCTANCE CHANNEL VM= MEMBRANE POTENTIAL EI= EQUILIBRIUM POTENTIAL OF ION
WHAT IS ANOTHER WAY TO CLASSIFY ION CHANNELS
MOLECULAR FAMILY
WHAT IS THE STRUCTURE OF THE KCSA BACTERIAL CHANNEL AND HOW WAS IT FOUND
HOMOLOGOUS WITH THE KIR CHANNEL, THE STRUCTURE WAS FOUND BY VISUALISING PROTEIN CRYSTALS IN X RAY
It contains a basic pore-forming unit comprising two transmembrane helices, M1 and M2, linked by a shorter re-entrant pore (P) helix and a loop (Fig. 4). The functional channel is formed from a tetrameric assembly of the 2TM + 1P unit.
WHAT IS THE STRUCTURE OF A KV CHANNEL
- 6 SUBUNITS
- VOLTAGE SENSOR ON THE 4TH
- PORE BETWEEN 5 AND 6
