DNA - Deoxyriobose Nucleic Acid
DNA - is a polymer of nucleotide.
Nucleotide - is a complex molecule consisting of 3 molecules linked together ie pentose sugar, phosphate group and nitrogenous base.
Structure of DNA:
- It's a polynucleotide.
- DNA later coils into helical shapes, this provides stability.
- Exsists as a double helix structure.
- These 2 chains run anti-parallel to each other. (one is 5' end to 3' end, the other is 3' end to 5' end)
- It's highly stable, to maintain the genetic information unchanged throughout life.
- The stability is maintained by the Hydrogen bonds
IMPORTANCE OF DNA REPLICATION
Importance of DNA Replication
- Inheritance of genes from parents to offsprings.
- Help in growth and repair.
- Avoid mutations.
DNA Replication - ability of a DNA to be perfectly copied as many times over, so as to maintain the same genetic material.
DNA replication is a semi-conservative replication.
Semi-conservative replication - method bywhich a DNA molecule is copied toform two identical molecules, each containing one strand from the original molecule and one newly synthesised strand.
STEPS INVOLVED IN DNA REPLICATION
- The two strands unzip and unwind due to the breaking of Hydrogen bonds in the presence of Helicase enzyme.
- The strand acts as a template, where by free nucleotides with complementary base, pair to those exposed on the template. (Free nucleotides are activated by an extra phospahte attaching to them)
- The nucloetides join to each other by the formation of Hydrogen bonds, catalysed by the enzyme DNA Polymerase.
- The short segments formed along the new strand (the lagging strand) are joined in the presence of the enzyme Ligase.