Download Pre-Lesson3: Growth (fill in the blanks)

Full Name: _____________________
Date: _______________
Pre-Lesson3: Growth (fill in the blanks)
Bacterial Cellular Morphology and Cellular Growth Patterns
Bacterial cells have a specific shape and this is called their morphology. With the Eubacteria
and many Archaebacteria, there are three main shapes. Provide the three shape names under
their shapes in the top part of the figure below:
Bacilli is pleural and are also called rods.
What is the singular of bacilli (or one cell)?
_______________
You will need to be able to distinguish between the genus Bacillus and a single bacillus. (Because all
scientific family names are capitalized and italicized, if you pay attention to
____________________, it is actually pretty simple to keep from getting confused on this.)
Name an example of a bacillus that you know: _______________________.
Different rod-shaped bacteria may have the rod ends blunted, rounded or pointed.
Cocci is pleural and are usually small spheres. What is the singular of cocci?
_____________. What is a cocci that you know? _____________________.
Spirilla is pleural and are spiral shaped; what is the singular of spirilla? ______________
(Sometimes complex spirals are called spirochetes, but I will not use that name.)
Other shapes are possible, they are largely based on one of three above shapes, and they are uncommon:
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What are oval shaped or very, very short rods called? __________________. Sometimes a
species of these may have all of the following varying shapes of cells: cocci, coccobacilli, and
short rods. It is fairly hard to determine the shape of these cells, so let us hope that your unknown
is not a coccobacilli!
What are bent rods (shaped like comma) called? _________________.
I do not use this name and will simply call them bent rods.
There are also “Disc” shaped cells that look like jelly-filled doughnuts. They appear like rods
when viewed from the side, but as cocci when viewed from the top. They may grow in filament
or hair of cells chained together. Some of the photosynthetic bacteria have this shape, but we will
not study them.
There are also “Irregular” shaped cells that have the shape of: _______________. These cells are often
pleomorphic (taking on more than one shape). Mycoplasmas (we will talk about them late in the term)
and some archaebacteria are irregular and pleomorphic.
Cellular Growth Patterns/(or Cellular Arrangements of Growth):
Eubacteria may be in single cells or in groups. This grouping is called a Cellular Growth Pattern (the
lab manual calls it a Cellular Arrangement of growth). Cellular Growth Patterns are due to the way a
species undergoes cell division and whether the dividing cells stick together in the process (their cell
walls stick).
What are two cocci, chains of cocci, and grapelike cluster of cocci called? Write these names in the lower
part of the figure above. (If unable to add to figure, write it here: ____________)
Cocci may also group as tetrads (groups of four) or as sarcina (groups of eight). Do not confuse the
Growth Pattern with the genus names Streptococcus and Staphylococcus (cocci species that grow in
chains and clusters respectively).
Diplo and strepto are also used for groupings of bacilli (diplobacilli), though bacilli are more commonly
called pairs (groups of two): _____________________.
Chains of bacilli that grow end to end grow in the shape of a/an: __________________________ and
palisades of bacilli which grow in the shape of a/an: _______________
A culture of one species usually has a pleomorphic cellular growth pattern. Pleomorphic means that the
culture will be what ___________________________________?
Spirals are an exception, as they generally grow only as single cells and are not pleomorphic.
Colony Morphology:
Be sure that you can
distinguish between
bacterial cellular
morphology and colony
morphology. Cellular
morphology refers to the
characteristic shape of
cells, while colony
morphology
refers to the characteristic
shape of an entire colony.
The former is a cellular
characteristic, the latter a
colonial characteristic.
You cannot use the terms
of one to describe the other.