What is a chromosome? Why do humans have 26 XY chromosomes why do ferns have 64 chromosomes?
In: Biology
Chromosomes hold dna. As organisms replicate they can mutate and give their children more or less dna. If the mutations help the organism it will probably spread through the population. Ferns have more because they randomly mutated more in beneficial ways.
Ok, firstly humans have 23 couples of chromosomes, 22 “normal ones” + 1 sexual ones (XY for males and XX for females).
Normally the DNA is partially open, so that the cell can read the information in it and use it to build proteins.
When the cell undergoes mitosis, asexual reproduction, the DNA is doubled and then extremely compressed in chromosomes, so that it’s easier to move it in both daughter-cells.
The numbers of chromosomes doesn’t seem to follow any rule and more chromosomes don’t equate to more complex organisms, but a variation in the number in humans leads to problems such as the down syndrome.
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