Chapter 9, Problem 9A

Summary Introduction

To explain:

Why cellular transport and cellular communication factors limit the cell size.

Introduction:

A cell grows until it reaches its size limit, then it either stops growing or divides. Most cells undergo division. Cell division helps a cell to reproduce and makes the organism grow and heal certain injuries. Most cells are less than 100µm in diameter. There are several factors that influence the small size of a cell.

Answer to Problem 9A

If a cell grows too big, it cannot transport nutrients and wastes effectively and efficiently. The cell communication is difficult in large cells. Hence cells remain small to have better cellular transport and communication.

Explanation of Solution

The movement of substances can be easily managed in a small cell than in a large cell. Plasma membrane is selectively permeable so it controls the transport of materials. Once inside the cell, substances move by diffusion. Diffusion over large distance is slow and inefficient. So the cells remain small to maximize the ability of diffusion and motor proteins to transport nutrients and waste products.As the cell grows, it has difficulty in expelling wastes out of the cell.

The cell size affects the cell’s ability to communicate instructions for cellular functions. If the cell becomes too large, it becomes impossible to send signals to various organelles.