How did they calculate a single sperm to have 37 megabytes of information?
In: Biology
That’s actually an extremely misleading number. The humane genome contains around 3.1 (men) to 3.2 (women) billion base pairs. Since the X chromosome is three times longer than the Y chromosome, women have a higher total genome length than men. A base pair is made of two of the four nucleobases: adenine, cytosine, guanine and thymine, but only the four combinations AT, TA, CG and GC are possible, because A and T only and always go together, and C and G only and always go together. These four combinations can be encoded with two bits, so that’s 6.2-6.4 gigabits, or about 750 megabytes for a full, exact copy of a human genome.
Now, even if you need 750 megabytes to store the “raw data” from a human genome, at least a computer scientist will have a hard time defining all of this as “information”. E.g. if you record 74 minutes of complete silence on a CD, the disc contains roughly 750 megabytes of “data” as well, but actually no “information”. Large parts of the human genome are repetitive, only a very small part actually differ between different individuals and from the difference, several base pair sequences only occur in a few well-defined varieties. Depending on how you “compress” or ignore this DNA that’s not unique, you could arrive at the conclusion that there’s only 37.5mb worth of DNA that’s “unique” in each sperm, but DNA isn’t the same as a .zip file, and while it’s useful to compress it when dealing with it as digital data, our bodies don’t work that way, so no, there is far more than 37.5mb of information in a single sperm. A sperm cell doesn’t just contain the unique parts of a person’s genome. It contains 1 full set of chromosomes (23/46 chromosomes, we have 2 of each chromosome). Every single one of the base pairs is present.
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