What is the difference between a colony and a cell on a plate?

What is the difference between a colony and a cell on a plate?

• A. A colony arises from a single cell or group of cells; a cell is an individual microorganism.
• B. A cell is formed when many cells join to form a colony.
• C. A colony refers to a population of cells in liquid culture only.
• D. A cell is always larger than a colony in a plate.

Answer: (A)

On a plate, a colony is a visible cluster that grows from a single cell (or occasionally a few cells) and becomes a population of descendants. A cell is an individual microorganism. You can’t see a single bacterium with the naked eye on a plate, but you can see the mass of cells—the colony—that results from many rounds of division. This is why colonies are used to estimate viable cells: each colony typically represents a colony-forming unit that started from one cell. The other ideas misstate where colonies form (on solid media, not in liquid culture) or what starts a colony (it can start from a single cell, not only from many joining), and they mischaracterize size relationships (a single cell isn’t a visible “larger” thing than a colony).

On a plate, a colony is a visible cluster that grows from a single cell (or occasionally a few cells) and becomes a population of descendants. A cell is an individual microorganism. You can’t see a single bacterium with the naked eye on a plate, but you can see the mass of cells—the colony—that results from many rounds of division. This is why colonies are used to estimate viable cells: each colony typically represents a colony-forming unit that started from one cell.

The other ideas misstate where colonies form (on solid media, not in liquid culture) or what starts a colony (it can start from a single cell, not only from many joining), and they mischaracterize size relationships (a single cell isn’t a visible “larger” thing than a colony).