Which Best Describes the Cell Theory Which Best Describes the Cell Theory?


Jane Flores

The cell theory is one of the fundamental principles of biology that describes the basic unit of life – the cell. This theory states that all living organisms are composed of cells, which are the smallest unit of life, capable of performing all necessary functions for survival. In this article, we will discuss the three main principles that make up the cell theory.

Principle 1: All living things are made up of cells

This principle is the foundation of the cell theory. It states that all living organisms, including plants, animals, and microorganisms are made up of one or more cells.

Cells can vary in size and shape depending on their function within an organism. For example, nerve cells have long extensions called axons to transmit signals over long distances, while red blood cells are small and disc-shaped to efficiently transport oxygen throughout the body.

Principle 2: Cells are the basic unit of structure and function in living things

This principle emphasizes that cells are not only the building blocks but also the functional units of life. Each cell contains specialized structures called organelles that perform specific functions necessary for life. For instance, mitochondria produce energy for cellular activities through a process called cellular respiration, while ribosomes synthesize proteins needed for growth and repair.

Principle 3: New cells come from pre-existing cells through cell division

This principle states that new cells arise from pre-existing ones through a process known as cell division. During this process, a parent cell divides into two or more daughter cells with identical genetic material. This process occurs in both unicellular organisms like bacteria and multicellular organisms like humans.


In conclusion, the cell theory provides a framework for understanding how living organisms function at their most basic level – the cellular level. It emphasizes how all living things share common characteristics at this level, despite their diversity in size, shape, and function. By understanding the three principles of the cell theory, we can appreciate the complexity of life and how it is organized at its most fundamental level.