1. Definition
According to scientific journal Nature, molecular biology is “ the field of biology that studies the composition, structure and interactions of cellular molecules such as nucleic acids and proteins that carry out the biological processes essential for the cells functions and maintenance” 1. Molecular biology is considered a specialized branch of biochemistry (study of the chemistry of molecules that are connected to living processes) 2.
2. Molecular versus, traditional and cell biology
According to the University of Queensland Diamantina Institute, Australia, traditional biology focuses on the study of whole living organisms and their interaction within populations, while cell biology focuses on cellular structures (e.g. organelles) and their molecular pathways as well as cell life cycles. On the contrary, molecular biology focuses on studying the components that compose these living organisms. During the last years, the technological discoveries led scientists to use and focus more on molecular biology 2.
3. Focus on DNA RNA and Proteins
Nucleic acids (DNA and RNA) and proteins are the main actors in molecular biology. These molecules are mainly constructed and encoded using their genetic instructions. Other molecules, such as lipids and carbohydrates can be studied for their interactions with nucleic acids and proteins 2.
4. Common molecular biology techniques 2 3
o Electrophoresis: is the separation of DNA, RNA or proteins according to their size using an electrical field. This allows the identification of entire molecules or fragments of molecules and ensures that the right molecules are being studied. The separation is mostly done using gel systems (agarose or polyacrylamide).
o Polymerase Chain Reaction (PCR): involves the amplification of very small amounts of DNA to make many DNA copies for further use in research. PCR can also be employed in site‐directed mutagenesis to add small point mutations into a gene.
o Restriction Digest: is the fragmenting of DNA into smaller pieces using enzymes that cleaves DNA at specific genetic sequences.
o Ligation: is the procedure of joining two fragments of DNA by an enzyme. It is mainly used for introducing a fragment of DNA or RNA in a genome.
o Blotting: is a technique that allows the identification of biomolecules following electrophoresis. The identification is made using a labeled probe or antibody.
o Cloning: involves the introduction of a gene into a host cell or organism. It is used for studying the effects of the inserted gene in the host organism, to make the host organism a large producer of the inserted genes or the corresponding proteins and to indicate where the gene products are expressed in the host organism. The introduction of a gene in a host is classified as follows: transformation (host is a bacterial or non‐animal eukaryotic cell), transfection (host is an eukaryotic cell) and transduction (gene inserted by a virus)
REFERENCES
1. Nature. Molecular Biology. Available at: https://www.nature.com/subjects/molecularbiology (Accessed: 1st December 2019)
2. Introduction to molecular biology. Diamantina Institute, University of Queensland,Australia Available at: https://di.uq.edu.au/community‐and‐alumni/sparq‐ed/cell‐andmolecular‐biology‐experiences/dna‐restriction‐and‐electrophoresis/introductionmolecular‐biology. (Accessed: 1st December 2019)
3. Rapley, R. Basic Molecular Biology Techniques. Mol. Biol. Biotechnol. 5th Ed. (2009). doi:10.1385/1‐59259‐870‐6