Final answer:
A pure culture originates from a colony formed by a single cell or group of cells that is genetically identical. Culturing such cells involves the growth of these organisms on agar plates using methods such as streak plating, and subsequent transfer to fresh media to maintain the culture.
Step-by-step explanation:
A single cell or group of related cells that produces a pure culture is referred to as a colony which originates from an individual microorganism. When this microorganism is isolated on an agar plate using the streak plate method, it reproduces to form clones of itself, resulting in a mass of cells called a colony. Each colony descends from a single cell, creating a population that is genetically identical. Therefore, in microbiology, when these colonies are transferred to a new medium, a pure culture is obtained which could be composed of bacteria, animal cells, or any other microorganism under study.
When cells from a primary cell culture reach a certain density, contact inhibition occurs which prevents further cell division. Subculturing the cells to a new medium with fresh nutrients can overcome this. Moreover, continuous cell lines derived from certain cells such as cancer cells, can be used to analyze the characteristics of cells that can proliferate indefinitely, without the typical limitations observed in primary cell cultures.
The concept of pure cultures is essential not only for studying microbiology but also for numerous applications in medicine, research, and the biotechnology industry.