Chromosomes are rod-shaped structures that carry genetic material. They are found with the nucleus of a cell. They are made up of DNA, RNA and proteins.
Their outer structure has two parts called chromatids. They are connected by a centromere.
The centromere is key when it comes to ensuring that there is a right balance of duplicate chromosomes present in the daughter cells during cellular division.
At the end of each tip are the telomeres, which are in charge of keeping the ends from becoming entangled and bonding to each other. Plus, they help similar chromosomes pair up and bond with each other during meiosis.
In humans, each cell contains 46 chromosomes arranged in 23 pairs. The only exceptions are sex cells (sperms and ova), which contain 23 chromosomes; but when fertilization takes place they create a cell with a full set of chromosomes, meaning, 46.
Out of these 23 chromosomes, the first 22 are called autosomes or autosomal. The last pair –the sexual chromosomes- are known are gonosomes or heterochromosomes (X and Y).
These last ones differ from the rest in that they are not always identical.
Women have two identical X chromosomes and men have an X chromosome and a Y chromosome, which is smaller.
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