DNA, or deoxyribonucleic acid, is a molecule found in the cells of all living organisms. It contains the genetic instructions that determine an organism's traits and characteristics. DNA is important because it is responsible for passing on genetic information from parents to offspring, allowing for the development and functioning of living organisms.
The chemical make-up of DNA consists of building blocks called nucleotides, which are made up of a sugar molecule, a phosphate group, and a nitrogenous base. The four nitrogenous bases found in DNA are adenine, thymine, guanine, and cytosine. These bases pair up in specific ways to form the double helix structure of DNA.
DNA contains instructions in the form of genetic code that determine an organism's traits. This code is made up of specific sequences of the four nitrogenous bases mentioned earlier. The order and combination of these bases determine the production of proteins, which are responsible for the physical characteristics and functions of an organism.
DNA replication is the process by which a cell makes an identical copy of its DNA. This process occurs during cell division and is essential for passing on genetic information to new cells. The double helix structure of DNA is unwound and each strand serves as a template for the production of a new complementary strand, resulting in two identical DNA molecules.
The size of DNA can vary greatly between species. For example, the human genome contains approximately 3 billion base pairs, while the genome of a fruit fly contains around 180 million base pairs. This size difference is due to variations in the amount of non-coding DNA, which does not contain instructions for protein production, among different species.