Delaney Caballero

Chromosomes

Chromosomes are DNA molecules packed into threadlike structures. They are what

chromatin condenses to form during cell division. Each chromosome is made up of DNA tightly

coiled many times around a type of protein, called histones, which support its structure. The

histones form a series of bead-like structures called nucleosomes that are connected by the DNA

strand. Chromosomes are located in both prokaryotic and eukaryotic cells. In eukaryotic cells,

chromosomes are found inside of the nucleus. In prokaryotic cells, there is a single chromosome

that is located in the nucleoid. The prokaryotic chromosome is much easier to manipulate than

the eukaryotic chromosome. Because of this, we know much more about the location of genes

and their control in prokaryotes. They are important to cells because they contain the cell’s

genetic information that is passed on to the next generation of cells. Unless the cell is dividing,

chromosomes are never visible, not even with a microscope. Almost everything that is known

about chromosomes has been learned from studying them during cell division. The centromere is

the connecting point for the arms of the chromosome. The short arms are called “p arms” and the

long arms are called “q arms”. The location of the centromere on each chromosome gives the

chromosome its specific shape and can be used to help describe the location of certain genes. If

there were no chromosomes in cells, then the cell would not have life because it would not have

the proper genetic information to reproduce or continue life. Because we cannot see

chromosomes unless the cell is dividing, the approximate size of a chromosome at the beginning

of mitosis is 5 µm, or 5 micrometers, while a cell is 1 µm, or 1 micrometer.