In cell biology, molecular biology and related fields, the word intracellular means "inside the cell". Cell biology (also called cellular biology or formerly cytology, from the Greek kytos, container) is an academic discipline that studies cells. ... Molecular biology is the study of biology at a molecular level. ... Drawing of the structure of cork as it appeared under the microscope to Robert Hooke from Micrographia which is the origin of the word cell being used to describe the smallest unit of a living organism Cells in culture, stained for keratin (red) and DNA (green) The cell is the...

It is used in contrast to extracellular (outside the cell). The cell membrane (and, in plants, the cell wall) is the barrier between the two, and chemical composition of intra- and extracellular milieu can be radically different. In most organisms, for example, a Na+/K+ ATPase maintains a high potassium level inside cells while keeping sodium low, leading to chemical excitability. In cell biology, molecular biology and related fields, the word extracellular means outside the cell. It is used in contrast to intracellular (inside the cell). ... Look up cell membrane in Wiktionary, the free dictionary. ... A cell wall is a fairly rigid layer surrounding a cell, located external to the cell membrane, that provides the cell with structural support, protection, and a filtering mechanism. ... ATPases are a class of enzymes that catalyze the decomposition of adenosine triphosphate (ATP) into adenosine diphosphate (ADP) and a free phosphate ion. ... General Name, symbol, number potassium, K, 19 Chemical series alkali metals Group, period, block 1, 4, s Appearance silvery white Standard atomic weight 39. ... For sodium in the diet, see Edible salt. ...

note: do not get confused between intracellular and intercellular, the latter meaning "between cells".