Download Name Period ______ BACTERIA [bacteria] [pl. of bacterium

Name _________________
Period ______
BACTERIA [bacteria] [pl. of bacterium], microscopic
unicellular prokaryotic organisms characterized by the lack
of a membrane-bound nucleus and membrane-bound
organelles. Once considered a part of the plant kingdom,
bacteria were eventually placed in a separate kingdom,
Monera . Bacteria fall into one of two groups,
Archaebacteria (ancient forms thought to have evolved
separately from other bacteria) and Eubacteria. A recently
proposed system classifies the Archaebacteria, or archaea,
and the Eubacteria as major groupings (sometimes called
domains) above the kingdom level.
Bacteria are grouped in a number of different ways. Most bacteria are
of one of three typical shapes—rod-shaped (bacillus), round (coccus,
and spiral (spirillum). The cytoplasm and plasma membrane of most
bacterial cells are surrounded by a cell wall; further classification of
bacteria is based on cell wall characteristics. They can also be
characterized by their patterns of growth, such as the chains formed
by streptococci. Many bacteria, chiefly the bacillus and spirillum forms,
can move, swimming about with the aid of flagella; other bacteria
have rigid rodlike hairs called pili that serve as tethers.
Bacteria are prokaryotes. That means that they do not have any organelles
that we have previously learned. No nucleus, no mitochondria, no
chloroplasts. They do have DNA but it is not contained in a typical nucleus
that has a membrane (covering). Below are the three main types of bacteria
so color and read about each.
The rod shaped bacteria
are known as bacillus or
if more than one, bacilli.
Some bacteria are found
in chains and the prefix
“strepto” is placed before
the bacteria type.
Some bacteria put in milk
is of this type
(lactobacillus) and so is
the infamous E. coli.
Round Bacteria (coccus or cocci)
The round bacteria are
known as coccus or
cocci(pl). The
arrangement of the
bacteria contributes to its
name. Ever had “strep”
throat? That would be
short for streptococcus
bacteria growing near
your tonsils.
Typical Spirillum
The third kind of bacteria
are the spiral shaped or
spirilla. A lot of these
kinds of bacteria cause
disease. Things that cause
disease are called
pathogens. One such
spiral bacteria is H. pylori
and it causes gastritis.