Many cells have a membrane protein that transports sodium ions into the cell in

Question

Many cells have a membrane protein that transports sodium ions into the cell in exchange for hydrogen ions moving out of the cell. This is an example of: a. antiport. b. symport. c. teleport. d. uniport. Use the letters at right to match the transporter or transport process numbered 15-20 with the correct mechanism or type of membrane transport. A given letter may be used more than once or not at all (1 pt each) 15. voltage-gated Na+channel a. simple diffusion 16.valinomycin b. ionophore 17. oxygen entering respiring cells c. porin 18. glucose transporter (Glut 1) d. ion channel 19. Na^+- glucose cotransporter f. primary active transport 20 Na^+-K^+ ATPase g. secondary active transport

Explanation / Answer

Na+/H+ exchanger is an example of antiport, it is also called as sodium–hydrogen antiporter or sodium–hydrogen exchanger. They are mainly found in the nephrons of kidney. This exchanger is largely responsible for maintaining the balance of pH. In the process of Urine production Angiotensin II up regulate this antiporter in the proximal convoluted tubule. This increase Na+ reabsorption in the exchange of H+ ions.

15. Voltage gated Na+ channels : (d) Ion channels

Na+ channels are member of group called ion channels , these type of channels are activated by change in the membrane electrical potential. Voltage-gated ion-channels are generally ion-specific, and other examples of ion channels are potassium (K+), calcium (Ca2+), and chloride (Cl–) ions channels.

16. Valinomycin: (b) Ionophore

Vallinomycin is an antibiotic circular peptide obtained from many streptomyces species. This antibiotic act by destroying electrochemical gradient cross the bacterial cell membrane by transporting potassium ions in and out of the cell uncontrollably. Hence it is an ionophore antibiotic .   

17. Oxygen entering respiring cells : (a) simple Diffusion

Different in the partial pressure of oxygen in oxygenated haemoglobin and active muscle tissue facilitate oxygen transport or release from haemoglobin to active muscles.

18. Glucose transport : (e) Transport protein

Gluts are integral membrane proteins that are mainly responsible for glucose transport in mammals. There are many type of Glut protein present. These isoform of Glut proteins plays a specific role in glucose metabolism determined by its pattern of tissue expression, substrate specificity, transport kinetics, and regulated expression in different physiological conditions.

19. Na+ Glucose transporter : (g) Secondary active transport

Na+Glucose Transporters are an example of Secondary active transport. This type of transporters use electrochemical gradient of Sodium ion created by primary transport (Na+/K+ ATPase) and move glucose uphill against the concentration gradient i.e from low to high concentration. Since both the molecules move in one direction it is called as symport.

20. Na+-K+ ATPase : (f) Primary active transport

The Na+/K+ ATPase are the example of primary active transport as they move ions against their electrochemical gradient using metabolic form of energy that is ATPs, it moves two K+ into the cell at the same time it sends three Na+ out of the cell . These pumps are highly important in animal cells as they maintain electrochemical gradient across the membrane.

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