Deoxyribonucleic Acid

  DNA(Deoxyribonucleic Acid) and Its Copy

DNA

We know that through reproduction organisms create new individuals that are similar to each other and those which look exactly similar to their parents. Do you know why? This is because the organisms looking similar possess similar body design. But is it possible to produce similar body designs? Yes, it is possible only when there is a method to produce similar copies of the blue print involved in reproduction process. This mechanism is called replication of DNA or copying.

We know that the nucleus contains chromosomes which carry information from parent to offsprings in the form of DNA molecules. DNA, which is the constituent of chromosomes present in the nucleus of each cell, passes from one generation to another.

DNA carries information for the formation of proteins and different proteins lead to different body types. So, reproduction needs to do the following:

(a) Create a DNA copy due to various chemical reactions.

(b) Separate two sets of DNA by retaining one copy in the parent and passing another copy to the new one.

(c) Form two cells as a result of cell division.

(d) Copying process shows some variations due to biochemical processes.

(e) These variations may be little or drastic.

Thus, we can say that DNA functions as a blue print of life as it is the information source for the organization of cells into tissues, tissues into organs, organs into organ systems into a body structure.

From the above discussion we can say that, creation of a DNA copy is the basic event in the process of reproduction. This results in the production of two similar copies of DNA in a reproducing cell. These similar copies are then transferred to two small daughter cells. Thus, during cell division, two copies of DNA are produced that gets separated into two similar cells. The parent cell divides to give rise to two new daughter cells.

These two newly formed daughter cells may be similar or may not be exactly similar (identical). Even in the higher level organisms, no two offsprings produced by the same parent (except identical twins) are exactly identical. They may however be similar to each other. The similarity or the non-similarity between the offspring depends on the process of DNA copying. This is because it is not possible for DNA copy to be exact replica of the parent copy at each time. There may be slight differences during copying. So, the two copies of DNA may be similar, but not identical. Sometimes there may be drastic variations, such individuals carrying the copy of DNA with drastic variations may fail to survive and die. On the other hand, some variations in DNA copies may be beneficial, thus helping in the creation of individuals which are able to survive in the environment in a better manner. This type of beneficial variations in DNA copying results in the evolution of species.