Cell Biology Notes - Biology Notes Online

Transfection Protocols – Methods, Steps, and Optimization

Sourav Pan (M.Sc. in Microbiology) • Updated October 10, 2026 • 33 min read

Four transfection methods showing lipid–DNA complexes, PEI–DNA complexes, calcium phosphate precipitates, and electrical delivery of DNA into cells.

Explore transfection protocols for cultured cells, including plasmid DNA, PEI, Lipofectamine, siRNA, and electroporation, with setup and troubleshooting.

Cytokinesis – Definition, Process, and Types in Plant and Animal Cells

Sourav Pan (M.Sc. in Microbiology) • Updated October 9, 2026 • 17 min read

Sequential animal-cell cytokinesis showing contractile-ring constriction, cleavage-furrow formation, the midbody bridge, abscission, and two separated daughter cells.

Cytokinesis divides a cell’s cytoplasm into daughter cells. Learn when it occurs, how it works in animal and plant cells, and how it differs from mitosis.

Cell Cycle: Definition, Phases, Checkpoints and Regulation

Sourav Pan (M.Sc. in Microbiology) • Updated October 8, 2026 • 27 min read

Cell Cycle - Definition, Phases, Regulation

Understand the cell cycle, including G1, S, G2 and M phases, interphase, mitosis, cytokinesis, G0, checkpoints and how cell division is regulated.

Checkpoints in the Cell Cycle – G1, G2, M and Regulation

Sourav Pan (M.Sc. in Microbiology) • Updated October 8, 2026 • 26 min read

Checkpoints in the cell cycle regulate DNA replication and division. Understand G1, G2, M, S-phase control, checkpoint proteins, and what happens when they fail.

Cell Organelles: Major Types, Functions, and Examples

Sourav Pan (M.Sc. in Microbiology) • Updated October 8, 2026 • 37 min read

Cell Organelles Structure and their Functions

Cell organelles are specialized cell structures with distinct roles. Explore major organelles, their functions, examples, and how organelle counts vary.

Cancer Cell – Structure, Characteristics, and Normal Cell Differences

Sourav Pan (M.Sc. in Microbiology) • Updated October 7, 2026 • 19 min read

Cancer Cell - Definition, Types, Morphology, Development

A cancer cell is an abnormal body cell in which normal control of cell growth, survival, and other cellular behavior has been disturbed. Cancer cells develop from normal cells after accumulation of mutations or other genetic alterations that change normal cellular regulation. The cell may continue proliferation when it should stop, survive when it should

Cell Differentiation – Definition, Process & Examples

Sourav Pan (M.Sc. in Microbiology) • Updated October 6, 2026 • 14 min read

Progression from a less-specialized cell through specification, determination, and differentiation as developmental potential becomes increasingly restricted.

Cell differentiation or cellular differentiation is a biological process by which an unspecialized or less-specialized cell becomes a specialized cell with particular structure, identity, and function. The cellular state changes during this process. It is not same as cell division. In cell division, new cells are produced. Differentiation commonly starts from a stem cell, progenitor

Gamete – Definition, Types, Formation, and Role in Fertilization

Sourav Pan (M.Sc. in Microbiology) • Updated October 6, 2026 • 15 min read

Gamete - Types, Formation, Functions, Examples

A gamete is a reproductive cell (sex cell) that carries genetic information in the form of deoxyribonucleic acid (DNA). During fertilization, one gamete can unite with another gamete. In animals, these cells are haploid and contain one set of chromosomes. When two haploid gametes fuse, a diploid zygote is formed. Ordinary body cells are generally

Egg Cell (Ovum): Structure, Function, Size & Fertilization

Sourav Pan (M.Sc. in Microbiology) • Updated October 5, 2026 • 13 min read

Cross-sectional diagram of a human secondary oocyte showing ooplasm, metaphase II spindle, cortical granules, oolemma, perivitelline space, first polar body, zona pellucida, and corona radiata.

The egg cell is the female reproductive cell, or female gamete, involved in sexual reproduction. In humans, the egg cell is commonly called an ovum. Egg cells occur in many sexually reproducing organisms, but here the human egg cell is mainly discussed. An egg cell is a single biological cell. It should not be confused

Osmosis: Definition, Process, Examples, and Osmotic Pressure

Sourav Pan (M.Sc. in Microbiology) • Updated October 4, 2026 • 17 min read

Three-stage osmosis diagram showing water crossing a selectively permeable membrane toward higher effective solute concentration and reaching dynamic equilibrium.

Osmosis is the net movement of solvent across a selectively permeable membrane. Learn the mechanism, tonicity, examples, osmotic pressure, and diffusion.