Chapter 7, Problem 40A

Summary Introduction

To summarize:

Cellular transport helps to maintain homeostasis within a cell.

Introduction:

A cell performs various biological processes and maintains a steady state. A cell can only function normally if a stable state is maintained inside the cell.

Explanation of Solution

The process of maintaining stable condition inside the cell is called as homeostasis. The environment both inside and outside the cell are always changing, hence regular and constant adjustments are required .Often homeostasis is achieved by moving substances into and out of the cell. During this process, the cell keeps the condition within an optimum range.

The plasma membrane plays a major role in transporting substances inside the cell. The structure of the plasma membrane consists of phospholipid bilayer. The phospholipid bilayer allows passage of water and some molecule ions. However some large molecules like glucose have to be transported inside the cell with the help of special proteins called as transport proteins which may or may not require energy. When the transport mechanism requires energy from the cell to complete the process it is known as active transport. It occurs when substances move from areas of lower to higher concentration against the concentration gradient. When the transport of substances takes place along the concentration gradient and requires no energy, it is known as passive transport.

Cellular transport is dependent upon the permeability of the membrane, solute concentration and size as well as charge of the solute. Solute particles move across the membrane via three important mechanisms − passive, facilitated and active transport. Some of these mechanisms involves use of energy and sometimes also include transport proteins.

Conclusion

Thus to maintain a steady environment a cell has to allow or remove many solutes from its inside to outside. Cellular transport helps to maintain the influx of various materials entering the cell.