BRS: I. CELL PHYSIOLOGY

Question 1

THESE ARE PROTEINS THAT ARE NOT IMBEDDED IN THE CELL MEMBRANE, NOT COVALENTLY BOUND TO MEMBRANE COMPONENTS AND ARE LOOSELY ATTACHED TO THE CELL MEMBRANE BY ELECTROSTATIC INTERACTIONS.

Answer 1

PERIPHERAL PROTEINS

Question 2

PROTEINS THAT ARE ANCHORED TO, AND IMBEDDED IN, THE CELL MEMBRANE THROUGH HYDROPHOBIC INTERACTIONS AND MAY SPAN THE CELL MEMBRANE.

Answer 2

INTEGRAL PROTEINS

Question 3

EXAMPLES OF INTEGRAL PROTEINS

Answer 3

ION CHANNELS
TRANSPORT PROTEINS
RECEPTORS
GUANOSINE 5′-TRIPHOSPHATE (GTP)–BINDING PROTEINS (G PROTEINS)

Question 4

CELL MEMBRANES ARE COMPOSED PRIMARILY OF PHOSPHOLIPIDS AND PROTEINS. PHOSPHOLIPIDS HAVE A __________ BACKBONE, WHICH IS THE HYDROPHILIC (WATER SOLUBLE) HEAD, AND TWO ________, WHICH ARE HYDROPHOBIC (WATER INSOLUBLE). THE HYDROPHOBIC TAILS FACE EACH OTHER AND FORM A BILAYER.

Answer 4

GLYCEROL; FATTY ACID TAILS

Question 5

THESE ARE THE ATTACHMENTS BETWEEN CELLS (OFTEN EPITHELIAL CELLS AND MAY BE AN INTERCELLULAR PATHWAY FOR SOLUTES, DEPENDING ON THE SIZE, CHARGE, AND CHARACTERISTICS.

Answer 5

TIGHT JUNCTIONS

Question 6

OTHER NAME FOR TIGHT JUNCTIONS

Answer 6

ZONULA OCCLUDENS

Question 7

EXAMPLE OF AN IMPERMEABLE TIGHT JUNCTION

Answer 7

RENAL DISTAL TUBULE

Question 8

EXAMPLE OF A “LEAKY” OR PERMEABLE TIGHT JUNCTION

Answer 8

RENAL PROXIMAL TUBULE
GALLBLADDER

Question 9

THESE ARE THE ATTACHMENTS BETWEEN CELLS THAT PERMIT INTERCELLULAR COMMUNICATION; FOR EXAMPLE, PERMIT CURRENT FLOW AND ELECTRICAL COUPLING BETWEEN MYOCARDIAL CELLS.

Answer 9

GAP JUNCTIONS

Question 10

THIS IS THE ONLY FORM OF TRANSPORT THAT IS NOT CARRIER MEDIATED, OCCURS DOWN AN ELECTROCHEMICAL GRADIENT (“DOWNHILL”) AND DOES NOT REQUIRE METABOLIC ENERGY AND THEREFORE IS PASSIVE.

Answer 10

SIMPLE DIFFUSION

Question 11

DIFFUSION CAN BE MEASURED USING THE FOLLOWING EQUATION:

Answer 11

J = − PA(C1 − C2)

J = FLUX (FLOW) (MMOL/SEC)
P = PERMEABILITY (CM/SEC)
A = AREA (CM2)
C1 = CONCENTRATION1 (MMOL/L)
C2 = CONCENTRATION2 (MMOL/L)

Question 12

WHAT ARE THE FACTORS THAT INCREASE PERMEABILITY

Answer 12

↑ OIL/WATER PARTITION COEFFICIENT OF THE SOLUTE INCREASES SOLUBILITY IN THE LIPID OF THE MEMBRANE.
↓ RADIUS (SIZE) OF THE SOLUTE INCREASES THE DIFFUSION COEFFICIENT AND SPEED OF DIFFUSION.
↓ MEMBRANE THICKNESS DECREASES THE DIFFUSION DISTANCE.

Question 13

CHARACTERISTICS OF CARRIER-MEDIATED TRANSPORT

Answer 13

STEREOSPECIFICITY
SATURATION
COMPETITION

Question 14

ANALOGOUS TO THE MAXIMUM VELOCITY (VMAX) IN ENZYME KINETICS

Answer 14

TRANSPORT MAXIMUM (TM)

Question 15

THIS OCCURS DOWN AN ELECTROCHEMICAL GRADIENT (“DOWNHILL”), DOES NOT REQUIRE METABOLIC ENERGY AND THEREFORE IS PASSIVE, IS MORE RAPID THAN SIMPLE DIFFUSION AND IS CARRIER MEDIATED AND THEREFORE EXHIBITS STEREOSPECIFICITY, SATURATION, AND COMPETITION.

Answer 15

FACILITATED DIFFUSION

Question 16

THIS OCCURS AGAINST AN ELECTROCHEMICAL GRADIENT (“UPHILL”), REQUIRES DIRECT INPUT OF METABOLIC ENERGY IN THE FORM OF ADENOSINE TRIPHOSPHATE (ATP) AND THEREFORE IS ACTIVE, IS CARRIER MEDIATED AND THEREFORE EXHIBITS STEREOSPECIFICITY, SATURATION, AND COMPETITION.

Answer 16

PRIMARY ACTIVE TRANSPORT

Question 17

EXAMPLES OF PRIMARY ACTIVE TRANSPORT

Answer 17

NA+, K+-ATPASE (OR NA+–K+ PUMP)
CA2+-ATPASE (OR CA2+ PUMP)
H+, K+-ATPASE (OR PROTON PUMP)

Question 18

THE TRANSPORT OF TWO OR MORE SOLUTES IS COUPLED. ONE OF THE SOLUTES (USUALLY NA+) IS TRANSPORTED “DOWNHILL” AND PROVIDES ENERGY FOR THE “UPHILL” TRANSPORT OF THE OTHER SOLUTE(S). METABOLIC ENERGY IS NOT PROVIDED DIRECTLY BUT INDIRECTLY FROM THE NA+ GRADIENT THAT IS MAINTAINED ACROSS CELL MEMBRANES.

Answer 18

SECONDARY ACTIVE TRANSPORT

Question 19

IF THE SOLUTES MOVE IN THE SAME DIRECTION ACROSS THE CELL MEMBRANE, IT IS CALLED

Answer 19

COTRANSPORT OR SYMPORT

Question 20

EXAMPLE OF COTRANSPORT OR SYMPORT

Answer 20

NA+-GLUCOSE COTRANSPORT IN THE SMALL INTESTINE AND RENAL EARLY PROXIMAL TUBULE
NA+–K+–2CL– COTRANSPORT IN THE RENAL THICK ASCENDING LIMB

Question 21

IF THE SOLUTES MOVE IN OPPOSITE DIRECTIONS ACROSS THE CELL MEMBRANES, IT IS CALLED

Answer 21

COUNTERTRANSPORT, EXCHANGE, OR ANTIPORT

Question 22

EXAMPLE OF COUNTERTRANSPORT, EXCHANGE, OR ANTIPORT

Answer 22

NA+-CA2+ EXCHANGE
NA+–H+ EXCHANGE