Nucleotides are monomeric units of nucleic acids. They are made of carbon, hydrogen, oxygen, nitrogen and phosphorus. Each nucleotide has a nitrogenous base, a pentose sugar and one to three phosphate groups Nitrogenous base: It is a heterocyclic compound that can be either a purine (adenine or guanine) or a pyrimidine (thymine/cytosine/uracil). The nitrogenous base … Read more


Lipids are a heterogeneous group of organic compounds made of carbon, hydrogen and a few atoms of oxygen. The term lipid is derived from greek word lipos, meaning fat. These substances are not soluble in water but dissolve in non-polar solvents such as benzene, ether, chloroform. This is because they contain long hydrocarbon chains that are non-polar … Read more

Amino Acids

Amino acids are building blocks of proteins. More than 300 amino acids are found in nature but only 20 amino acids are standard and present in protein because they are coded by genes. Other amino acids are modified aminoacids and called non-protein amino acids. They are compounds of carbon, hydrogen, oxygen and nitrogen, where the … Read more

Organic Materials

Organic compounds found in animal and plant body are carbohydrates, lipids, amino acids, proteins, nucleotides, hormones and vitamins. Some of these remain in colloidal form in the aqueous intracellular fluid. Others exist in non-aqueous phases like the lipid membrane and cell walls. Carbohydrates Carbohydrates are compounds of carbon, hydrogen and oxygen, where the ratio between … Read more

Cellular Pool

The total biomolecules found in a cell is commonly known as cellular pool It consists of both inorganic and organic compounds. The cellular pool consists of Water – 6 Inorganic materials Carbon, Hydrogen, Oxygen – 9 Major Metal elements – Major non-metal elements – Minor metal elements – traces (Zn, Mn, Mo, Co) Minor non-metal elements … Read more

Plant cell vs Animal cell

Differences between a Plant cell & Animal cell Plant cell Animal cell A plant cell is usually larger in size. Animal cell is comparatively smaller in size It is enclosed by a rigid cell wall The plasma membrane is surrounded by a complex extracellular matrix It contains a large central vacuole An animal cell often … Read more

Prokaryotic vs Eukaryotic cell

Differences between a Prokaryotic cell & Eukaryotic cell Prokaryotic cell Eukaryotic cell Absence of definite nucleus, nuclear membrane, nucleolus A well defined nucleus bound by a nuclear membrane, and nucleolus is present Membrane bound organelles like Mitochondria, Endoplasmic Reticulum, Golgi Apparatus, Lysosome, Chloroplasts etc. are absent. Presence of membrane bound organelles Cell respiration is carried … Read more

Nucleolus & Chromatin

Nucleolus: Fontana (1781) discovered the presence of round oval bodies called Nucleoli (Nucleolus-singular) embedded in the nucleoplasm. It does not have a membrane. Nucleoli are associated with the nuclear organizing portion of the chromosomes. The size of the nucleoli is related to the activities of the cell. Cells that are actively involved in protein synthesis … Read more


Nucleus is the heart of the cell. It controls all the cellular activities. So it is referred to as the controlling centre of the cell. It was first discovered by Robert Brown in 1831. The study of nucleus is termed as Karyology. Nucleus is present in all eukaryotic cells except mature RBC of humans and … Read more

Centrosomes and Centrioles

Centrioles are non – membranous cylindrical bodies found near the nucleus in the centrosome, a granular mass that serves as an organizing center for microtubules. These are seen in animal cells and flagellated plant cells. Centriole can be viewed only during cell division. Centrosome usually contains two centrioles. A pair of centrioles is called diplosome. They … Read more