Piero Scaruffi(Copyright © 2013 Piero Scaruffi | Legal restrictions )
These are excerpts and elaborations from my book "The Nature of Consciousness"
The cell itself is the elementary unit of the body (in the case of bacteria, one cell is the whole body), but it has its own structure. Its behavior is driven by the instructions of the DNA, but its function are roughly to transform nutrients into energy (generically, metabolism), to carry out some function thanks to that energy, and to reproduce (mitosis).
Each cell is limited by a membrane and is supported by a skeleton called a “cytoskeleton”. The cytoskeleton is made of a protein called "tubulin", which forms filaments called "microtubules". Most living beings are eukaryotes: their cells contain a nucleus that contains the genetic material (DNA and RNA). The nucleus is the information storage of the cell. It is also the place where DNA is transformed into mRNA. The cell contains many ribosomes, each of which is a machine that manufactures proteins based on the instructions received from the nucleus in the form of mRNA. There is also genetic material in some organelles of the cell called “mitochondria”. Mitochondria are the cell’s "power plant," because they convert nutrients into energy, creating the nucleotide that is the "molecular currency" of intracellular energy. Mitochondria have their own DNA, separate from the cell’s main DNA. Mitochondria are also self-replicating.
Prokaryotes (such as bacteria) are made of simpler cells that do not have a nucleus.
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