Discovery of Cell: History, Cell Theory, Types, Structure

Have you ever wondered who discovered the cell? Or what are cells? Or how are they formed? If you have, then this article about the discovery of cells will provide you with all the information related to cells. A cell is the basic structural and functional unit of all life forms. Moreover, all living things on Earth are made up of one or more cells.

Organisms with a single cell are known as unicellular organisms, such as bacteria. Furthermore, most unicellular organisms are classed as microorganisms. In comparison, organisms with two or more cells are called multicellular organisms, such as plants and animals. The number of cells in plants and animals can vary from species to species. Read on to find more about the discovery of cells.

Who Discovered the Cell?

In 1665, a scientist named Robert Hooke made the first discovery of cells. He was able to discover the cell because of the invention of the microscope. Robert Hooke’s microscope was a recreation of Anton van Leeuwenhoek’s microscope with 300 times magnification. After he invented the microscope, he made numerous observations, and one observation was from very thin slices of a bottle cork.

During Hooke’s observation of thin slices of a bottle cork, he discovered a multitude of tiny pores. He named them cells. The name ‘cell’ came from the Latin word ‘Cella’, meaning ‘a small room’. Furthermore, it resembles cells inhabited by Christian monks in a monastery. The name also came from the word ‘Cellulae’, which meant the six-sided cell of a honeycomb.

Cell Theory

Theodor Schwann and Matthias Jakob Schleiden are two scientists who first developed the cell theory in 1839. Although one more scientist named Rudolf Virchow also contributed to the theory. However, his contribution to the theory was not recognised.

Schleiden suggested that every structural part of a plant was made up of cells. In addition, he also suggested that a crystallisation process either within other cells or from the outside made cells. On the other hand, Theodor Schwann states that the structures of animals are also composed of cells. From these conclusions about plant and animal cells, two principles of the cell theory were postulated. They are:

• All living organisms are made up of one or more cells.
• The cell is the basic unit of structure and organisation in organisms.

Later in 1855, Rudolf Virchow added the third principle to the cell theory, i.e.,

• All cells arise from pre-existing cells.

Modern Interpretation of Cell Theory

The modern cell theory includes:

• All known living things are composed of one or more cells.
• All living cells arise from pre-existing cells by division.
• The cell is the fundamental unit of structure and function in living organisms.
• The activity of an organism depends totally on the activity of independent cells.
• Energy flow occurs within cells.
• Cells contain DNA and RNA. One can find DNA in the chromosome and RNA in the cell nucleus and cytoplasm.
• All cells are basically the same in chemical composition in organisms of similar species.

Components of Cells

The cell structure is made up of various components. Students can check various components of cells below:

Cell Membrane

The cell membrane or plasma membrane surrounds the cytoplasm of a cell. The plasma membrane is the outer boundary of an animal cell. However, a cell wall usually covers the cell membrane in plants and prokaryotes. The cell or plasma membrane separates and protects a cell from its surrounding environment.

Cytoskeleton

The Cytoskeleton organise and maintain the shape of cells. It helps in various functions. The Cytoskeleton helps during endocytosis, the uptake of external materials by a cell. It also helps in cytokinesis, the separation of daughter cells after cell division. Furthermore, it moves parts of the cell in growth and mobility processes.

Genetic Material

There are two different types of genetic materials, i.e.,

• Deoxyribonucleic acid (DNA)
• Ribonucleic acid (RNA)

Cells store their long-term information in DNA. Moreover, the DNA sequence of an organism encodes all the biological information contained in that organism.

Cells use RNA to transport information (e.g., mRNA) and enzymatic functions (e.g., ribosomal RNA). Furthermore, cells use transfer RNA (tRNA) molecules to add amino acids during protein translation.

Organelles

Organelles are parts of the cell and specialised in carrying out one or more vital functions. Similar to human organs like the heart, lung, and kidney, cell organelles perform different functions.

Types of Cell

There are two types of cells, namely

• Prokaryotic Cell: It does not contain a nucleus but has a nucleoid region. For example, bacteria and archaea. Prokaryotic cells were the first form of life on Earth. These cells are simpler and smaller in size ranging from 0.5 to 2.0 μm in diameter.
• Eukaryotic Cell: It contains a nucleus. For example, plants, animals, fungi, slime moulds, protozoa, and algae. Eukaryotic cells are about fifteen times wider than a typical prokaryote. Furthermore, they are thousand times greater in volume.

Difference Between Prokaryotic and Eukaryotic Cells

Students can get a general idea of the difference between Prokaryotic and Eukaryotic Cells from the table below:

We hope this detailed article on the Discovery of Cell helps you. If you have any queries regarding this article or the exam, feel to drop a comment below. We will get back to you at the earliest.

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