April 18, 2008

Describing Unicellular Morphology

Posted in Microbiology tagged , , , at 10:25 pm by D. Borst

Bacteria, like other organisms, come in a variety of shapes and sizes. Unfortunately, the way scientists have described these unicellular entities does is not necessarily related to how we describe shapes in everyday life. Below, I will discuss some of the basic descriptors used to discuss the form of these cells.

Cocci is a term that is used to describe cells that are spherical. These cells are small and compact, and appear to be small round shapes under a microscope. Coccus bacteria can form many different types of colonies, including pairs, or diplococci; chains, or streptococci; tetrads, a square arrangement of four cells in a plane; sarcina, an arrangement of eight cells with the center of each cell at the vertex of a cube; and in grape like clusters known as staphylococci. You the names of these structures probably remind you of various pathogens such as Staphylococcus aureus and Streptococcus pneumoniae, which are organisms that take the forms relating to their names.

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