Introduction:

DNA, short for Deoxyribonucleic Acid, is the marvel of life's instruction manual.

Comprising of nucleotides, DNA carries the genetic code that defines us.

This article explores the fascinating world of DNA, from its structure to its crucial functions.

I. Nucleotides of DNA

A. The Building Blocks:

The essential building blocks of DNA are called nucleotides.

A phosphate group, a sugar (deoxyribose), and a nitrogenous base make up each nucleotide.

B. Nitrogenous Bases:

• Adenine (A), Thymine (T), Cytosine (C), and Guanine (G) are the four bases.

• A pairs with T, and C pairs with G, forming the DNA double helix

II. DNA's Hetero- and Auto-Catalytic Activities:

Heterocatalytic Activities:

• Genetic information is carried by DNA, which transmits qualities from one generation to the next.

• Through RNA intermediates, it controls the synthesis of proteins.

B. The Autocatalytic Process:

• The processes of DNA replication and repair are autocatalytic.

• DNA has methods for proofreading mistakes.

III. DNA Replication Models

Semi-Conservative Model:

According to a theory put forth by Watson and Crick, every new DNA strand consists of both an original and a newly manufactured strand.

Conservative model:

Implies that a brand-new DNA molecule is created while the original DNA molecule is preserved.

Dispersive Model:

Implies that the original DNA pieces split and combine with freshly made DNA.

IV. Direction of DNA Replication:

A. Unidirectional Replication:

• In unidirectional replication, DNA synthesis proceeds in only one direction.

• Typically occurs at the replication fork.

B. Bidirectional Replication:

• In bidirectional replication, DNA synthesis occurs in both directions from the origin of replication.

• Common in circular DNA, like that of bacteria.

V. Enzymes for DNA Metabolism:

A. Nucleases:

These enzymes break down nucleic acids by cleaving phosphodiester bonds.

B. Polymerase:

DNA Polymerase adds nucleotides during replication.

C. Replicase:

A specialized polymerase that replicates RNA genomes.

D. Ligase:

Joins DNA fragments by catalyzing the formation of phosphodiester bonds.

E. RNA Primers:

Short RNA sequences used as starting points for DNA synthesis.

F. Replicons:

Segments of DNA that replicate independently.

G. Helicase:

Unwinds the DNA double helix, separating the strands.

H. Topoisomerases:

Resolves supercoiling and tension in DNA during replication.

Conclusion:

DNA, with its nucleotides, heterocatalytic and autocatalytic functions, and diverse models for replication, continues to captivate scientists.

The direction of replication varies, while essential enzymes ensure accurate DNA metabolism.

This microscopic molecule, with its monumental role in genetics, truly holds the keys to life's mysteries.

Find the hand written notes to this topic below:

Anatomy of DNA: it's functions, replication models, direction of replication and enzymes for DNA metabolism (Free Notes)