Prokaryotes are organisms whose cells lack a nucleus. They do not have membrane-bound organelles like mitochondria. The two major domains of prokaryotes are bacteria and archaea. Escherichia coli (E. coli) is a common rod-shaped bacterium found in the intestines. It is an example of a prokaryote that divides via binary fission and lacks membrane-bound organelles.

1. Prokaryotes
Carissa Fletcher
Inter Community School Zurich

2. Background
The prokaryotes are a group of organisms whose cells lack a cell nucleus
(karyon).
The organisms whose cells do have a nucleus are called eukaryotes. Most
prokaryotes are unicellular organisms
Prokaryotes do not have a nucleus, mitochondria, or any other
membrane-bound organelles.
In prokaryotes the intracellular water-soluble components (proteins, DNA
and metabolites) are located together in the same area enclosed by
cell membrane, rather than separated in different cellular
compartments.
The division to prokaryotes and eukaryotes reflects two distinct levels of
cellular organization rather than biological classification of species.
Prokaryotes include two major classification domains: the bacteria and the
archaea.
Archaea were recognized as a domain of life in 1990. These organisms
were originally thought to live only in inhospitable conditions such
as extremes of temperature, pH, and radiation but have since been
found in all types of habitats.

3. Background
• E. coli is a Gram-negative, facultative anaerobic rod-shaped
bacterium that is commonly found in the lower intestine of warm-
blooded organisms (endotherms).
• Most E. coli strains are harmless, but some serotypes can cause
serious food poisoning in humans
• The harmless strains are part of the normal flora of the gut, and can
benefit their hosts by producing vitamin K2, and by preventing the
establishment of pathogenic bacteria within the intestine.
• E. coli and related bacteria constitute about 0.1% of gut flora and
fecal–oral transmission is the major route through which pathogenic
strains of the bacterium cause disease.
• In 1997 strain MG 1655 was found to be a circular DNA molecule 4.6
million base pairs in length, containing 4288 annotated protein-
coding genes
• Major role in Biotechnology and genetic engineering and is also a
model organism for microbiology.
http://abcnews.go.com/topics/lifestyle/health/e-coli-
infection.htm?mediatype=Image

4. 2.2.1- 3 Draw and label a diagram of the ultrastructure of
Escherichia coli (E. coli) as an example of a prokaryote.

5. 2.2.4 State that prokaryotic cells divide by binary fission.

6. 2.3.4 Compare prokaryotic and eukaryotic cells.
Feature Prokaryotes Eukaryotes