Deoxyribonucleic Acid (DNA) is a nucleic acid that carries the genetic information in the cells and normally its role is storage and can be compared with code or a secret number. It is responsible for the building of other cells as it contains the information and instructions needed to build other constituents of cells such as proteins and Ribonucleic acid. The DNA has components but the component that is responsible for ferrying the genetic information is known as genes. A gene is a sequence of DNA that contains genetic information and can influence an organism’s phenotype. The other parts are used in the regulation of this genetic information (Matt, 2006).
According to Robert (1974), chemically DNA is built of two repeating polymers /strands of simple units called nucleotides, which are made of sugars and phosphate groups that are held together by ester bonds and linked to bases. Each sugar is attached to 4 molecules known as bases. A base linked to a sugar is known as a nucleoside while a base linked to phosphate is known as a nucleotide. It is the sequence of these bases that encodes information. The backbone of DNA is made of alternating phosphate and sugar residues. These strands are antiparallel as they run in the opposite direction. Genetic information is read using the genetic code which specifically gives the sequence of amino acids within the proteins. The code is read through a process known as Transcription which is done by copying the stretches of DNA into the related nucleic acid RNA. (Robert, 1974).
In cells, DNA is organized into structures called chromosomes. Chromosomes duplicate before cells divide in a process called DNA replication (Andrew, 2003). In animals, plants and fungi (eukaryotes) DNA is found in the cell nucleus and occurs in a linear manner in the chromosome while in the prokaryotes (bacteria and arch ea) is found in the cell cytoplasm and in a circular manner in the chromosome. In the chromosomes, DNA is organized and compacted by chromatin proteins. The interaction of DNA and other proteins is guided by compact structures. In living organisms doesn’t exist as a single molecule but as an association of molecule pairs, all the functions of DNA depend on interaction with proteins (Andrew, 2003).
References
- Ridley Matt. (2006), Discoverer of the genetic code, Harper Collins Publishers
- Olby Robert (1974), The path of double Helix, Macmillan Publishers
- Andrew Calladine, (2003), understanding DNA, Elsevier Academic Press