Short answers, pulled from the story.
Cell biology, also called cellular biology or cytology, is the branch of biology that studies the structure, function, and behavior of cells. It covers both prokaryotic and eukaryotic cells and includes subtopics such as cell metabolism, cell communication, the cell cycle, biochemistry, and cell composition.
Robert Hooke first described cells in 1665, observing a piece of cork under a compound microscope and publishing his findings in Micrographia. He named the structures "cells" because they resembled the small rooms occupied by monks in a monastery.
Cell theory states that all living things are made up of cells, that cells are the structural and functional units of organisms, and that all cells arise from pre-existing cells. Matthias Schleiden and Theodor Schwann established the first two principles in 1838, and Rudolf Virchow added the third nineteen years later.
Cell biologists use techniques including cell culture, fluorescence microscopy, phase-contrast microscopy, confocal microscopy, transmission electron microscopy, cytometry, and cell fractionation. Each method is suited to different aspects of cell structure and function.
Cytopathology is the scientific branch that studies and diagnoses diseases at the cellular level, examining samples of free cells or tissue fragments. It is commonly used to diagnose cancer and some infectious and inflammatory conditions; a well-known example is the Pap smear, which screens for cervical cancer and precancerous cervical lesions.
Understanding cell structure and function is fundamental to all biological sciences and essential for research into diseases including cancer. Cell biology is interconnected with genetics, molecular biology, immunology, medical microbiology, and cytochemistry, and cell culture techniques are used in the development and manufacture of drugs, vaccines, and therapeutic proteins.