Chromosomes

Chromosomes. Everyone has them, every living thing with a nuclei in their cells has them. Every plant, every animal, every fungus and a selection of microbes has/have chromosomes. Basically, all of the genetic information of an organism with chromosomes is stored in the chromosomes (except mitochondrial DNA, but that’s weird stuff and is arguably not part of the organism’s genome) which, during cell division, bunch up and double up so they look like tiny, fat X’s. Many organisms have an even number of chromosomes, largely due to the nature of sexual reproduction, which requires an even number of chromosomes to form sex cells, but the range of the number of chromosomes any organism has varies widely based on species. For example, humans have 46 chromosomes, the same as the Reeves’s muntjac and Sable antelope. wolves, jackals, dogs and chickens all have 78 chromosomes, shrimp and two rat species have around 92, gypsy moths and giraffes both have 62, zebrafish and rice have the same number of chromosomes, 24. The organism with the most chromosomes is the Adders-tongue plant, with over 1,000 chromosomes (one Wikipedia page says 1440, another says 1262, so I’m just being vague), and the organism with the least chromosomes (not counting those without them) is the male Jack jumper ant, which has a single chromosome due to ant sexual behaviors (female jumper ants have a normal number of chromosomes for their species, 2).

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