Molecular Basis of Inheritance


DNA is a double helical structure of which was cracked by Watson and Crick based. It carries all the genetic information. DNA helix made up of strands. Each strand is made with repeating units of the nucleotides. The nucleotide consists of 3 components which are, ribose or deoxyribose sugar, nitrogenous base (purines or pyrimidines) and phosphate. Due to the presence of negatively charged phosphate groups DNA is negatively charged and this negatively charged phosphate groups are stabilized by basic protein known as histone.

DNA Structure:

DNA is made up of 6 molecular structures that comprise of one phosphate molecule and five carbon sugar,deoxyribose. Nucleotide is a basic building block of a DNA. A nucleotide is made up of one of the 4 bases,which are sugar molecule, and phosphate molecule.A sugar-phosphate chain is the backbone of a DNA molecule and bases are on the inside. Nucleotide subunits are attached together to create a DNA strand which providing polar stability.The DNA structure is three-dimensional which arises from chemical and structural features of 2 polynucleotide chain. A purine base pairs up with pyrimidine base. For instance guanine pairs with cytosine. hydrogen bond hold the two strands that are complementary to each other and the direction of the strands are antiparallel.


DNA Replication:

DNA Replication is a process by two new identical copies of DNA are from a single DNA molecule. DNA is a self-replicative molecule. It is a process of biological inheritance. The replication time in prokaryotes takes only a few minutes but in eukaryotes it takes hours. DNA is a double helix which is made up of two DNA strands and two strands are complementary to each other. At the time of replication these two strands of a helix separate to form two new DNA molecules. After the formation of the DNA strands, one strand is similar to one of the strand and the other strand is complementary to the parent strand. This type of replication is called semi-conservative replication.

In DNA replication, DNA polymerase in the most important enzyme, which is involved.

Central Dogma:

Central Dogma explains about how the genetic information transfer from generation to generation occurs in a bologycal system. This also explains about DNA replication process and then gets converted into messenger RNA with the help of transcription process. Then this mRNA or messenger RNA is translated to form proteins.Crick was first introduce about the central dogma. In retroviruses, the transfer process of genetic information is opposite,RNA to DNA to mRNA to Protein.

DNA Packaging:

The process starts when The negatively charged DNA is wrapped around special positively charged protein molecules called histones. A nucleosome is a combined loop of DNA and protein. The packaged nucleosomes into a thread sometimes called as "beads on a string" . The end result is a fiber known as chromatin of eukaryotes.


In coding, decoding, regulation and expression of genes Ribonucleic acid or RNA is a polymeric essential molecule in various biological roles.In some viruses RNA replaces DNA or deoxyribonucleic acid as a carrier of genetic codes and It functions in cellular protein synthesis. Adenine, guanine, cytosine, and uracil are the 4 nitrogenous bases in RNA.

Human Genome Project:

The Human Genome Project or HGP was an international scientific research project. The aim of this project to determining the base pairs that creates the human DNA, Also to indentify and mapping all of the genes of the human genome from both a physical and a functional standpoint. The HGP project remains the world's largest collaborative biological project. The advances of genetic engineering techniques have made this project possible. In 1984 the idea was picked up by the US government, then the planning started, after that in 1990 the project launched and on April 14, 2003 was announced completed.


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