Describe the process of semi-conservative replication and why is it so important?

The process of DNA replication involves unwinding the original DNA strand by the enzyme DNA helicase. This enzyme breaks the hydrogen bonds between complimentary bases forming two single strands of DNA. Each original strand acts as a template from which a new strand can be formed. Complimentary bases pair with the exposed template strand: Adenine with thymine and guanine with cytosine. It is condensation reactions that pairs these complimentary nucleotides together as water is eliminated and this is catalysed by DNA polymerase. The bases are held together with hydrogen bonds: 2 hydrogen bonds between A-T and 3 between C-G. You then have two DNA molecules with one original strand and one new strand, hence the name semi-conservative replication as half of the original strand is conserved in each new molecule.
Semi-conservative replication is involved in the process of mitosis- this is cell division. Cell division is important to enable the organism to grow and to replace old and dead cells. Without cell division and constant replenishment the organism would die.