Here are interesting and fun facts about cells, the building block of life:
- Cells are the fundamental unit of life.
While there are different types of cells, they all have a cell membrane, a region containing DNA, and cytoplasm. A single cell is a living organism. More complex organisms contain many cells. Cells only arise from other living cells (not spontaneously). - Robert Hooke discovered cells in 1665 and named them for their resemblance to monastery cells.
Hooke examined cork cells under a compound microscope. He described his findings in a book named Micrographia. - The word cell comes from the Latin word for “small room”.
The Latin word is “cellula”. - The two main types of cells are eukaryotic and prokaryotic.
Eukaryotic cells include those of plants, animals, fungi, and protozoa. These cells contain a membrane-bound nucleus that contains the DNA and organelles that perform specific processes. Prokaryotic cells are those of bacteria and archaea. Their DNA is in a nucleoid region and specialized processes occur openly in the cytoplasm. - Eukaryotic cells have a nucleus, while prokaryotic cells have a nucleoid region. Both contain DNA.
DNA (2′-deoxyribonucleic acid) codes for RNA (ribonucleic acid), which directs the cell to make proteins. In contrast, a virus contains either DNA or RNA and isn’t alive in the same way as a cell because it requires a cell for reproduction. - The first cells appeared on Earth around 4 billion years ago. They were prokaryotic cells.
Eukaryotic cells likely arose when one prokaryotic cell became an obligate parasite within another prokaryotic cell. This theory explains why mitochondria in eukaryotic cells have their own DNA. Eukaryotic cells likely arose 1 to 1.5 billion years after the appearance of the first prokaryotic cell. - You can’t see most cells without a microscope.
Nearly all cells are invisible to the naked eye. Most cells range from 1 to 100 micrometers in diameter. However, there are exceptions. For example, an ostrich egg is technically a single cell. The largest single-celled organism is the algae Caulerpa, which grows up to 10 feet (3 meters). - The human body contains about 40 trillion cells.
The human brain accounts for about 80 million cells. But, there are more bacterial cells than human cells in the body. Around 95% of your body consists of bacteria, which mainly reside on the skin and in the digestive tract. - Groups of similar cells can form tissues, while groups of different tissues can form organs.
Some organisms consist of a single cell. In multicellular organisms, cells with similar structures and functions form tissues. For example, groups of muscle cells form muscle tissue. Groups of tissues can form organs. For example, the heart contains muscle tissue, connective tissue, epithelial tissue, and nervous tissue. - Cells have variable life spans, ranging from a few days to an organism’s lifetime.
Some cells in the digestive tract only live a few days, while nervous cells in your brain can live as long as you do. Cells are programmed for death after a certain number of divisions (apoptosis). Cancer cells dismiss this programming and reproduce uncontrollably.
References
- Bianconi, E.; Piovesan, A.; et al. (November 2013). “An estimation of the number of cells in the human body”. Annals of Human Biology. 40 (6): 463–71. doi:10.3109/03014460.2013.807878
- Campbell, N.A.; Williamson, B.; Heyden, R.J. (2006). Biology: Exploring Life. Boston, Massachusetts: Pearson Prentice Hall. ISBN 9780132508827.
- Karp, G. (2009). Cell and Molecular Biology: Concepts and Experiments. John Wiley & Sons. ISBN 9780470483374.
- Orgel, L.E. (December 1998). “The origin of life–a review of facts and speculations”. Trends in Biochemical Sciences. 23 (12): 491–5. doi:10.1016/S0968-0004(98)01300-0
- Schopf, J.W.; Kudryavtsev, A.B.; Czaja, A.D.; Tripathi, A.B. (2007). “Evidence of Archean life: Stromatolites and microfossils”. Precambrian Research. 158 (3–4): 141–55. doi:10.1016/j.precamres.2007.04.009