BIOPHYSICS N°11 (FILL)

Primary active transport is directly powered by .........

ATP hydrolysis

......... allows glucose to enter the erythrocyte to be metabolized

GLUT-1

Active transport is an endergonic process that, in most cases, is coupled to the

hydrolysis of ..........

ATP

The key to the (Na+- K+)-ATPase is the phosphorylation of a specific ........... of

the transport protein

Aspartyl residue

Lactose permease requires a ............... gradient

Proton

In active transport, a specific molecule is transported from .......... concentration to

......... concentration. Such .......... process must be coupled to a sufficiently

............. process to make it favorable

Lower, higher, endergonic, exergonic

Conductance is the reciprocal of .........

Resistance

Active transport must be coupled to .......... producing reaction

Free energy

A hallmark of the (Na+- K+)-pump is that it is blocked by a class of compounds

knows as ..............

Cardiotonic steroids

Ronald Kaback established that the two major conformational states of lactose

permease E1 an E2 can interconvert only when their H+ and lactose binding sites

are either both .......... or both ..........

Empty, full

Glucose is exported from brush border cells to the bloodstream via a separate

passive-mediated uniport system similar to ..........

GLUT-1

Since glucose enhances Na+ resorption, which in turn enhances water resorption,

..........., in addition to salt and water, should be fed to individuals suffering

diarrhea

Glucose

Ca2+-ATPase actively pumps two Ca2+ ions out of the cytosol at the expense of ATP

hydrolysis, while counter transporting two or three ..............

Protons

The most important gradients across the cell membrane are those for potassium

and ...............

Sodium ions

The energy for active transport comes from ATP generated by respiration in .............

Mitochondria

Active transport requires an input of metabolic energy and is always mediated by

transporters that use the metabolic energy to pump the solute against ..............

Concentration

Coupled transporters couple the ........... transport of one solute across the

membrane to the ............ transport of another

Endergonic, exergonic

Cells may express secondary active transporters that are electrogenic, such as ..............

Lactose permease

The function of a channel is to facilitate the passive flow of ions across the

hydrophobic bilayer according to ............

Fick's law

The (Na+- K+)-pump is located in the plasma membrane and has both .......... and

............ subunits

⍺ and β

The uptake of glucose or amino acids from the intestinal lumen against their

electrochemical gradients occurs in symport with ......... moving back down its

electrochemical gradient into the intestinal epithelial cell

Na+

Digitalis inhibits the (Na+ - K+)-pump. This decreases the Na+ gradient across the

sarcolemma of the muscle cell and [Ca2+) in the muscle cell .............. This

increases the contractile force of the heart muscle cell.

Increase

The energy source for glucose transport into brush border cells is the

................. gradient.

Electrochemical

(Na+ -K+)-ATPase is located on the capillary side of the brush border cell and

function to maintain a low internal ............

Na+ concentration

The glucose is exported to the bloodstream via ............

Passive-mediated transport

Enzyme reaction involving hydrolysis are ..............

Catabolic

Uphill transport means transport ..............

against the concentration gradient

(Na+ - K+)- ATPase was the first characterized by ..............

Jens Skou

The overall stoichiometry of the reaction catalyzed by (Na+ - K+)-ATPase is .............

3Na+ (in) + 2K* (out) + ATP + H2O <---> 3Na+ (out) + 2K+ (in) + ADP + Pi

All cells consume large fraction of the ATP they produce -up to .............. in nerve cells.

70%