Lab 1: Comparison of Sizes and Shapes of Microorganisms

State the basic shapes of bacteria.

Coccus - are spherical or oval-shaped cells. The plural meaning is "cocci". Bacillus - are rod shaped cells. The plural meaning is "bacilli". Spiral - are corkscrew-shaped cells.

State and describe the different arrangements of cocci.

Diplococci - are arranged in two pairs of cells. Streptococci - are arranged in a chain (line) of cells. Tetrad - are arranged in four pairs of cells. Sarcinae - are arranged in a four dimensional cube of cells. Staphylococci - is arranged in a irregular cluster shape of cells.

State and describe the different arrangements of bacilli.

Single bacilli - has one rod shape arrangement. Diplobacilli - has two pairs of cells. Streptobacilli - are arranged in a chain (line) of cells after division.

When given an oil immersion microscope, a prepared slide of a microorganism, and an ocular micrometer, be able to determine the size of that organism in micrometers.

The eyepiece (on the microscope) contains a scale that appears superimposed on the focused specimen.

State and describe three different spiral forms.

Vibrios - are curved bacilli. Spirillums - are thick, rigid spirals. Spirochetes - are thin, flexible spirals.

Differentiate a yeast from a coccus-shaped bacterium by its size.

Yeast is 10µm and cocci is approximately 0.5 - 1.0µm.

Describe the appearance of a typical yeast.

Yeast is a unicellular, oval or spherical shaped fungi.