Have you ever wondered How does the DNA transmit characteristics from parents to offspring?
To know this, it is essential to know the structure and functionality of DNA.
The concept of DNA came into existence in the twentieth century. The results of several experiments were considered to conclude that DNA is the genetic material. Thus, it was necessary to understand how this molecule is responsible for the incredible diversity among the organisms.
The double helix structure of DNA was proposed by Watson and Crick in 1953. DNA consists of two long chains of sub-units twisted around one another to form a double-stranded helix. The sub-units of each strand are nucleotide, each of which contains any one of the four chemical constituents called bases.
- Adenine (A)
- Thymine (T)
- Guanine (G)
- Cytosine (C)
The information is stored in DNA as a code made up of these 4 bases. These bases pair up with each other to form units. A is paired with T and C with G. This pairing between the bases is said to be complementary.
Each base is attached to a sugar molecule and a phosphate molecule. The base, sugar and phosphate, together called as a nucleotide which forms the double helical structure.
The double helical structure looks like a spiral staircase. Sugar and phosphate forms the backbone of the chain, and the base pairs held the two intertwined chains. A molecule should satisfy four conditions to serve as a genetic material. A genetic material should be able to replicate, store the information, express the information and vary the information.
So what is DNA replication?
For the maximum transmission of the information from parent to offspring, the characters or the information need to be copied and separated. This happens through cell division. During cell division, the genetic material of cells replicates and doubled in amount. It is then divided equally through mitosis into daughter cell. The other stage where the genetic materials replicate is during the formation of gametes.
How DNA stores and express the information?
The information that is inherited from the parent needs to be stored in the offspring. This information may be active or even still sometimes. There is every chance that particular information may or may not be expressed by the cell where it is present. Also it may be active at a particular point of time or inactive sometimes.
What is Variability of Information in DNA?
The heritable change in the genetic material is through the process called mutation. It is the change in chemical composition of DNA. If mutation occurs in the gametes, the change will be transmitted to offspring, with time, the mutation will be passed to future generations and distributed in the population. The variations may be chromosome numbers, arrangement of chromosomes between each other and within. The process of mutation leads to evolution.
The basic complement of DNA is called its genome. It is made up of one or more long molecules of DNA that are organized into chromosomes. The regions of chromosomes DNA that are involved in the cell’s production of proteins are genes. Each chromosome in the genome carries a different array of genes. The human genome project has estimated that humans have around 20000 to 25000 genes.