Question

Give a summary of active transport. Be sure to include why it is consider "active," what molecule is required for "active" transport, the direction of this movement and give three examples. * Your answer

Answer 1

ANSWER :-

POINT 1 : Lets consider there is a membrane which separates a beaker into two compartments. The membrane is a semi-permeable membrane which allows only certain molecules or ions to pass through them. In one compartment there is large concentration of a molecule lets consider NaCl and in the other compartment the concentration is less. Normally, there is direct transfer via diffusion from an area of high concentration to an area of low concentration but when this process is reversed there is requirement of energy to create the backward transport and this is called as active transport.

POINT 2 : Lets consider the example of intestinal cells. The space within the intestine is called as intestinal lumen and this is in association with the enterocytes which are the epithelial cells lining the intestine. They are present on the intestinal villi. Basically, in the first process, there is entry of the sodium ions from the enterocytes into the intestinal lumen. This creates a greater concentration of sodium ions in the lumen and less in the enterocyte. This is responsible for driving the movement of glucose molecules via a co-transporter into the enterocyte which is against the concentration gradient by means of active transport. This is the symporter system.

POINT 3 : This process can also be seen in the roots of the plants. The root hairs are basically provided with carrier protein molecules which usually work in accordance with energy molecules such as ATP that is an output of cellular respiration to mediate transport of mineral ions from the soil into the root. There is less concentration of ions outside the root hair and more concentration of ions inside but the cells cannot lose their ions and hence active transport plays a vital role in maintaining the initial concentration and adding additional ions to the cells.

POINT 4 : The third example includes the process in which components like lipid molecules and hormones are being taken up by the cells by means of receptor-mediated endocytosis in which ATP molecules are utilised to drive the absorption of the components against the concentration gradient.

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