An atom that has a positive or negative charge is called: an ion. In an atom, protons have a positive electrical charge and electrons have a negative electrical charge. Families or groups on the periodic table share similar chemical properties because, each element has the same number of electrons.

Unlike protons, electrons can move from atom to atom. If an atom has an equal number of protons and electrons, its net charge is 0. If it gains an extra electron, it becomes negatively charged and is known as an anion. If it loses an electron, it becomes positively charged and is known as a cation.

The cell membrane is selectively more permeable to K than Na and hence there are more k inside than the outside, and hence outside is more positive then the inside.

It acts to transport sodium and potassium ions across the cell membrane in a ratio of 3 sodium ions out for every 2 potassium ions brought in. In the process, the pump helps to stabilize membrane potential, and thus is essential in creating the conditions necessary for the firing of action potentials.

Na,K-ATPase, the Na+ pump, is a transmembrane protein belonging to the P-type ATPase family. Its primary physiological role is the maintenance of large gradients, inward for sodium (Na+) and outward for potassium (K+), across the plasma membrane of all animal cells.

The sodium-potassium pump carries out a form of active transport—that is, its pumping of ions against their gradients requires the addition of energy from an outside source.

The inhibition of the Na/K pump will allow Na ions to accumulate in the cell, as K ion will fall. So if the Na/K pump was inhibited and stops working, then many functional problems will occur in the cell. Na ion concentration will accumulate within the cell and intracellular K ion concentration falls.

The sodium-potassium pump maintains the electrochemical gradient of living cells by moving sodium in and potassium out of the cell. The primary active transport that functions with the active transport of sodium and potassium allows secondary active transport to occur.

The sodium-potassium pump is an antiporter transport protein. The sodium-potassium pump is a very important protein in our cell membranes. The pump can be used to generate ATP when supplies are low by working in the opposite way.

Carrier proteins such as uniporters, symporters, and antiporters perform primary active transport and facilitate the movement of solutes across the cell’s membrane.

CONTENTS

• Antiport Pumps.
• Symport Pumps.
• Endocytosis.
• Exocytosis.

Active transport systems use an energy source (usually ATP) to drive the movement of molecules against a concentration gradient. The best example of active transport is the Na+/K+ATPase.

Passive transport doesn’t require energy (ATP), active transport does require energy. Passive transport moves molecules WITH the concentration gradient (high to low), while active transport moves molecules AGAINST the concentration gradient (Low to High).

In Active transport the molecules are moved across the cell membrane, pumping the molecules against the concentration gradient using ATP (energy). In Passive transport, the molecules are moved within and across the cell membrane and thus transporting it through the concentration gradient, without using ATP (energy).