STRUCTURE OF Chromosom1

A chromosome is a structure that occurs within cells and that contains the cell s genetic material. That genetic material, which determines how an organism develops, is a molecule of deoxyribonucleic acid (DNA). A molecule of DNA is a very long, coiled structure that contains many identifiable subunits known as genes.
In prokaryotes, or cells without a nucleus, the chromosome is merely a circle of DNA. In eukaryotes, or cells with a distinct nucleus, chromosomes are much more complex in structure.

The structure of chromosomes and genes
Today we know that a chromosome contains a single molecule of DNA along with several kinds of proteins. A molecule of DNA, in turn, consists of thousands and thousands of subunits, known as nucleotides, joined to each other in very long chains. A single molecule of DNA within a chromosome may be as long as 8.5 centimeters (3.3 inches). To fit within a chromosome, the DNA molecule has to be twisted and folded into a very complex shape.


Words to Know
Deoxyribonucleic acid (DNA): The genetic material in the nucleus of cells that contains information for an organism s development.
Eukaryote: A cell with a distinct nucleus.
Nucleotide: The building blocks of nucleic acids.
Prokaryote: A cell without a nucleus.
Protein: Large molecules that are essential to the structure and functioning of all living cells.