Avatar for Sourav Pan

Sourav Pan

Founder of Biology Notes Online, Biology & Microbiology Educator, M.Sc. in Microbiology
Expertise
Microbiology, Immunology, Cell Biology, Molecular Biology, Genetics, Biotechnology, Biochemistry, Botany, Zoology
Education
University of Calcutta
Profile Last Updated: August 10, 2026

Sourav Pan is the founder and sole author of Biology Notes Online. He holds a Bachelor of Science (B.Sc.) degree and an M.Sc. in Microbiology from the University of Calcutta. He creates educational resources covering microbiology, immunology, biotechnology, genetics, cell biology, botany, zoology, and other life-science subjects.

His goal is to make complex biological concepts easier to understand through well-structured, student-friendly articles based on academic textbooks, peer-reviewed research, and authoritative scientific sources. In addition to writing new content, he regularly reviews and updates articles to improve their accuracy, clarity, and educational value.

Gene Expression Profiling – Definition, Uses, Limitations

Gene Expression Profiling - Definition, Uses, Limitations

What is gene expression? What is Gene Expression Profiling? Gene Expression Profiling Definition Gene expression profiling (GEP) is a technology for identifying the genes that are active in a given sample of cells or tissue. This technique enables profiling of genes that are differentially expressed in disease states; thereby providing diagnostic and prognostic information. Tools … Read more

Next Generation Sequencing – Principle, Steps Involved, and Applications

Next Generation Sequencing - Principle, Steps Involved, and Applications

Next-Generation Sequencing (NGS) is a technology for high-throughput DNA and RNA sequencing. It allows for the rapid and simultaneous analysis of millions of DNA fragments, enabling comprehensive genomic studies such as genome sequencing, transcriptome analysis, and epigenetic profiling. NGS has revolutionized the field of genomics, providing a faster and more cost-effective way to study the … Read more

Yeast Artificial Chromosomes (YACs) – Definition, Structure, Construction, Uses

Yeast Artificial Chromosomes (YACs) - Definition, Structure, Construction, Uses

What is Yeast Artificial Chromosomes (YACs)? Yeast artificial chromosomes (YACs) are the result of a recombinant DNA cloning technique used to isolate and propagate extremely large DNA segments in a yeast host. The YAC cloning system enables the replication of exogenous DNA segments as linear molecules on a significantly larger scale than is possible with … Read more

PAM Sequence (Protospacer adjacent motif) – Definition, Functions, Properties

PAM Sequence (Protospacer adjacent motif) - Definition, Functions, Properties

What is PAM Sequence (Protospacer adjacent motif)? Protospacer Adjacent Motif, or PAM, is a type of two-factor authentication that tells Cas to only cut the foreign DNA that is invading. Properties of PAM sequence Spacers/protospacers PAM sequences Functions of PAM Sequence 1. Role of PAM in spacer acquisition 2. Role of PAM in interference 3. … Read more

Rolling Circle Replication –  Mechanism, Importance

Rolling Circle Replication -  Mechanism, Application

What is Rolling circle replication? Rolling circle replication is a unidirectional and asymmetric process of nucleic acid replication. It is the process by which multiple copies of circular DNA or RNA molecules is synthesized rapidly. This mechanism is commonly seen in bacterial plasmids, bacteriophages and certain plant and animal viruses. In this type of replication … Read more

Cas9 Protein – Structure, Types, Function

Cas9 Protein - Structure, Types, FunctionCas9 Protein - Structure, Types, Function

Name  Cas9 endonuclease Alternative name spCas9/spyCas9 Organism  Streptococcus pyogenes serotype M1 Molecular weight ~163KDa Gene  cas9 Location on chromosome 0.85 to 0.86Mb Protein CRISPR-associated endonuclease Cas9/Csn1 Cofactor Mg2+ Biological processing  Interference- defense response to phage.Maintaining CRISPR repeat sequences Functions DNA and RNA bindingMetal ion binding3’-5’ exonuclease activityEndonuclease activity  What is Cas9 Protein? Structure of Cas9 HNH … Read more

Semiconservative Replication of DNA – Mechanism

Semiconservative Replication of DNA - Mechanism

Mode of DNA replication Imagine yourself in 1953, right after the discovery of the double helix structure of DNA. What are some burning questions you and other scientists might have? One big question concerned DNA replication. The double helix shape of DNA gave a tantalising hint about how copying might happen. It seemed likely that … Read more