DNA replication is the process by which a cell makes an identical copy of its DNA before cell division. It is essential for reproduction as it allows the transfer of genetic traits from parents to offspring. During DNA replication, the double-stranded DNA molecule unwinds and each strand acts as a template to produce a new complementary strand. This results in two identical DNA molecules containing the same genetic information as the original DNA.

1. IMPORTANCE OF D.N.A. COPYING IN REPRODUCTION.

2. Genetics: The scientific study of(1)the mechanism of inheritance by which characters pass from parents to off springs, and (2)the causes of hereditary variation in living organisms related by descent. Gregor Johann Mendel(1822-1884)was the pioneer of classical genetics. He is appropriately called ‘father of genetics.’

3. Gene: A gene is a molecular unit of heredity of living organisms. Chromosome: They are highly condensed chromatin fibers . Chromatin fiber: During interphase, the genetic material is in the form of very long,extremely thin, dark staining fibers called chromatin fiber. Chromatin:It is made up of two substances D.N.A.(40%)and histones(60%).

4. What is D.N.A.? Deoxyribonucleic acid ,D.N.A. is a nucleic acid that contains genetic instructions used in development and functioning of all known organisms. It is made up of two long molecule chains that are wound spirally around a common axis in a double helix structure. This information is coded on 4 bases : ADENINE, CYTOSINE,GUANINE, THYMINE. The genetic code is passed on via mitosis , miuesis or binary fission. But prior to this process D.N.A. replication takes place.

5. D.N.A. Replication: D.N.A. is a biological process that occurs in all living organisms and copies their D.N.A., it is the basis for biological inheritance.The process starts with one double strand D.N.A. molecule and produces 2 identical copies.It takes place in a specific location of genome called origin.

6. Importance of D.N.A. copying in reproduction:- 1.D.N.A. copying helps in transferring the basic traits ,characters and structure of living organisms from parent to off spring. 2.Slight variations are induced in the off springs, as no biological reaction is 100% exact thus the new D.N.A. formed during replication are similar but not identical. Sometimes these variations are useful.

7. If the D.N.A. replication is normal then the characters passed on are similar but if the Parent D.N.A. is exposed to radiation or drugs then the genetic information may change, this leads to formation of mutant gene which causes abnormalities in the offspring produced, it is called as Mutation.

8. D.N.A. IS THE SOFTWARE OF LIFE.