Facts about human chromosomes

The discovery of human chromosome is one of the most amazing scientific achievements. The genetics, a study of genes, tries to explain what are genes and their vital constituent long molecules called DNA, and how they work. DNA is made of simpler units arranged in such a way to form a long large molecule. The order of these units is something like a cryptogram, carrying important genetic information. The “language” used by DNA is known as the genetic code, and it is readable by various organisms that learn from this genetic inscription how to conduct and operate different functions necessary for healthy living. The information within a particular gene differs between one organism and another. Each form of a single gene is called an allele. Therefore, different allele of the same gene gives different instructions, causing the wide diversity of life forms. Sometimes, the random changes in genes may occur. These are known as mutations. Mutations create new alleles and consequently, new traits. This process is important in evolution, which is a progression of change in all forms of life over generations.

A chromosome is an organized structure of DNA and protein that is found in cells. It is a single piece of DNA containing many genes, regulatory elements and other nucleotide sequences. Each chromosome has approximately 65 million DNA molecules. A chromosome contains about 1000 genes.

Human genetics shows that we have approximately 30,000 different genes spread out over the 46 chromosomes. The nucleus of a cell, is where the DNA is coiled up into chromosomes.

Every cell has 46 chromosomes, with the exception of reproductive cells. Twenty-two pairs of the chromosomes have similar size, shape and genetic information. The twenty-third pair determines the sex of the human being, and it may be composed of either two x chromosomes for the females, or one x and one y chromosome for males.

Francis Crick and James Watson discovered the structure of DNA on February 28, 1953. They found that the structure of DNA could separate into two long strands to make copies of itself.

DNA is short for Deoxy-ribo-Nucleic Acid, a nucleic acid that contains the genetic instructions used in the development and functioning of all known living organisms.

DNA molecules are arranged one after another, very much like pearls on a long string.

The genome is the entirety of an organism's hereditary information. The complete human genome consists of approximately 3 billion DNA molecules.

If the entire DNA from person’s cells were stretched out into a single thread, it would reach to the moon and back about one million times!