Number of molecules in the human body
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Total Number of Molecules in the Human Body
The human body is made up of an extremely large number of molecules. Estimates suggest that an average adult body contains about 7 × 10²⁷ molecules. This vast number is distributed across the body’s approximately 37 trillion (3.7 × 10¹³) individual cells, with each cell containing a huge number of molecules on its own134.
Major Molecular Components: Water, Proteins, and Triglycerides
Most of the molecules in the human body fall into three main categories: water, proteins, and triglycerides. Water makes up about 57% of the body’s mass, proteins about 17%, and triglycerides another 17%. Together, these three types of molecules account for about 92% of the body’s mass. Minerals make up another 7%, and only about 2% of the body’s mass is made up of other types of molecules.
Elemental Composition and Molecular Diversity
At the elemental level, nearly 97% of the body’s mass comes from just four elements: oxygen, carbon, hydrogen, and nitrogen. The remaining 3% is mostly calcium, phosphorus, sodium, potassium, and chlorine. Each of the body’s trillions of cells contains a unique set of molecules, contributing to the body’s overall molecular diversity.
Microbial Cells and Their Molecules
In addition to human cells, the body also contains about 38 trillion microbial cells, which actually outnumber human cells. These microbes add even more molecules to the total count, although they are not included in the main estimate for human molecules.
Conclusion
In summary, the human body contains roughly 7 × 10²⁷ molecules, mostly in the form of water, proteins, and triglycerides, spread across about 37 trillion cells. The body’s molecular makeup is dominated by a few key elements and is further enriched by trillions of microbial cells1234.
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Most relevant research papers on this topic
How Low Can You Go? The Numbers of Cells That Make Up Bodies: Large Numbers and Small Numbers
This book helps understand the small numbers of cells in organisms by comparing their numbers to grains of rice in a bowl, helping to visualize the complexity of cell numbers in various organisms.
DOI
Determination of the number of RAD51 molecules in different human cell lines
The RAD51 protein in human cells has a capacity of 20000 to 100000 molecules, which can simultaneously load at least 7 DNA double-strand breaks, providing parameters for quantitative understanding and modeling of RAD51-involving processes.
The Origin of Stars, Planets and Galaxies
Our bodies are made up of 65 percent oxygen, 19 percent carbon, 10 percent hydrogen, 3 percent nitrogen, and 3 percent everything else, with 60% of particles being hydrogen, which was made just a few minutes after the universe began.
DOI