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Molecular biology is a branch of science that overlaps with chemistry and biology. It deals with the study of cells at a molecular level.

Definition of molecular biology

Molecular biology is defined as the field of biology that encompasses the study of cellular molecules such as proteins and nucleic acids, their structure, composition and functions. Molecular biology emerged as a branch of study when the double helix structure of the DNA was discovered way back in 1960s. DNA is present in all living organisms and is a self replicating substance that forms the prime constituent of chromosomes. Key components involved in molecular biology are DNA, RNA and proteins.

DNA stands for Deoxyribonucleic Acid. DNA is the carrier of genetic information. It consists of two long polymers called as nucleotides. The double helix structure is stabilized with hydrogen bonds.

DNA basics | Image source:

RNA stands for Ribonucleic Acid. This molecule consists of a long chain of nucleotides. There are three types of RNA - messenger RNA, ribosomal RNA and transfer RNA.

Proteins are made up of amino acids.

What do molecular biologists do?
Molecular biologists primarily study the processes of replication, translation and transcription. Translation is the process wherein RNA is used to produce proteins where as transcription is the process where DNA is copied to RNA.

Central dogma of molecular biology
The central dogma of molecular biology can be briefly summed up as a two step process where in genetic information flows from DNA into proteins. The DNA encodes RNA and RNA in turn encodes proteins. This implies that genetic information flows in the cells from the DNA to messenger RNA and from there finally it reaches the proteins.

Did you know: A gene is the basic unit of heredity. Except for a few genes, most genes are the same across people. It is these few different genes that contribute to each person’s unique physical features.

Uses of molecular biology
Molecular biology has made a huge contribution to medical research. Applications of molecular biology includes discovery of new drugs for treatment of diseases and also for disease prevention and cloning.

In molecular cloning, one molecule is replicated to produce cells with identical DNA molecules. It typically involves a host and a source. The source is the species whose DNA has to be cloned and the host is an organism that serves as the host for replication of the DNA. The prime basis of these experimental techniques is that the chemical structure of DNA across all living organisms is essentially the same. Thus the source DNA will be replicated along with the host’s DNA replication process.

The process of molecular cloning typically includes:

  • Selection of the host organism and the small piece of DNA that will host the foreign DNA (this is called the cloning vector)
  • Cleaving of the vector DNA using enzymes to ensure that the configuration of the cloning vector is compatible with the foreign DNA
  • Purification of the DNA to be cloned and then treating it with enzymes so that its ends are compatible with the cloning vector
  • Generation of recombinant DNA - Mixing of the DNA from the cloning vector and foreign source. This is called recombinant DNA
  • This recombinant DNA is then inserted into the host organism for the replication to take place

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