Difference Between Cell and Atom

The key difference between cell and atom is that a cell is made of molecules whereas atoms make up molecules.

Cells are the smallest functioning unit in a living organism. It contains many macromolecules. Meanwhile, atoms make up these macromolecules. Hence, an atom is the smallest unit of matter. Usually, a cell is on the micrometre scale while an atom is in the angstrom scale.

1. Overview and Key Difference
2. What is a Cell
3. What is an Atom
4. Side by Side Comparison – Cell vs Atom in Tabular Form
5. Summary

What is a Cell?

A cell is the smallest functioning unit of living organisms. In other words, it is the smallest unit of life. Therefore, we call it the building block of life. There are different types of cells such as microorganisms, animal cells and plant cells. They have different structures. But, all these cells have an outer membrane which holds the content inside.

Figure 01: A Structure of a Typical Cell

When considering the structure of a cell, it contains a cytoplasm enclosed with a cell membrane, and the cytoplasm holds different organelles such as mitochondria. Therefore, different macromolecules, such as proteins, nucleic acid, carbohydrates, lipids, etc., make up the cells.

What is an Atom?

Atom is the smallest particle of a chemical element that can exist. Therefore, it is the smallest unit of matter, and a certain atom represents the properties of the chemical element to which it belongs. All gases, solid matter, liquids and plasma contain atoms. These are minute units; typically the size is around 100 picometers.

Figure 02: Typical Structure of an Atom

When considering the structure of an atom, it contains a nucleus and electrons moving around the nucleus. Further, protons and neutrons (and there are some other subatomic particles as well) make up the atomic nucleus. Typically, the number of neutrons, protons and electrons are equal to each other, but in the case of isotopes, the number of neutrons is different from that of protons. We call both protons and neutrons “nucleons”.

Around 99% of the atom’s mass is centred in the nucleus because the mass of an electron is almost negligible. Among these subatomic particles, a proton has +1 charge; an electron has -1 charge and a neutron has no charge. If the atom has equal numbers of protons and electrons, then the overall charge of the atom is zero; lack of one electron results in a +1 charge and a gain of one electron gives -1 charge to the atom.

What is the Difference Between Cell and Atom?

A cell is a biological unit, while an atom is a chemical unit. Besides, the key difference between cell and atom is that a cell is made of molecules whereas atoms make up molecules. Also, when considering the composition of these units, a typical cell contains cytoplasm, cell membrane, nucleus, etc. while an atom contains small subatomic particles such as electrons, protons and neutrons.

Moreover, a further difference between cell and atom is that a cell contains macromolecules such as proteins, carbohydrates, lipids and nucleic acid while molecules are made of atoms.

Summary – Cell vs Atom

A cell is a biological unit, while an atom is a chemical unit. In summary, the key difference between cell and atom is that a cell is made of molecules whereas atoms make up molecules.

Reference:

1. Cooper, John A., et al. “Cell.” Encyclopædia Britannica, Encyclopædia Britannica, Inc., Available here.

Image Courtesy:

1. “Simple diagram of animal cell (en)” By domdomegg – Own work (CC BY 4.0) via Commons Wikimedia
2. “Atom Diagram” By AG Caesar – Own work (CC BY-SA 4.0) via Commons Wikimedia