what is a chromosome

A chromosome is a thread-like structure made up of DNA and proteins called histones that support its structure. Chromosomes are found in the nucleus of almost every cell in our body, and they carry the genetic material of an organism. Each chromosome has a constriction point called the centromere, which divides the chromosome into two sections or "arms". The location of the centromere on each chromosome gives the chromosome its characteristic shape and can be used to help describe the location of specific genes. Chromosomes are not visible in the cells nucleus, even under a microscope, when the cell is not dividing. However, the DNA that makes up chromosomes becomes more tightly packed during cell division and is then visible under a microscope. Chromosomes display a complex three-dimensional structure, which plays a significant role in transcriptional regulation. Humans have 23 pairs of chromosomes (46 in total): one set comes from the mother and one set comes from the father. Of these 23 pairs, one pair are sex chromosomes, so they differ depending on whether you are male or female (XX for female or XY for male). The other 22 pairs are autosomes (non-sex chromosomes) and look the same for both males and females.