Bacteria
Prokaryotes are single cell organisms that lack a
nucleus. Their size range form 1-5 micrometers
which is smaller than most eukaryotic cell.
Epulopiscium fisheloni is a gigantic prokaryote
measuring at 500 micrometers long.
All prokaryotes were placed in the Kingdom
Monera. Biologist divided the Monera into 2
different groups: eubacteria and archaebacteria.
Eubacteria
 Is the larger of the 2 Kingdoms
 Freshwater, salt water, on land and within the
human body. Example: E. Coli lives in the human
intestines.
 Surrounded by a cell wall that protects the cell from
injury and determines its shape.
The cell wall of eubacteria contains peptidoglycan, a
carbohydrate. Inside the cell wall is a cell membrane
that surrounds the cytoplasm. Some eubacteria have a
second, membrane outside the cell membrane making
it especially resistant to damage.
Archaebacteria
 Looks similar to eubacteria
 Equally small, lack nuclei, have cell walls
but chemically different
Archaebacteria lacks the peptidoglycan of
eubacteria and have different membrane
lipids. The DNA sequences of key
archaebacteria genes are more like those of
eukaryotes than those of eubacteria.
Archaebacteria
Archaebacteria may be ancestors of
eukaryotes. They live in extremely hard
environments that produce methane gas.
Methogens live in oxygen-free environments
such as mud and digestive tracts of animals.
They live in extremely salty environments
such as Utah Great Salt Lakes, hot springs
where the temperatures approach the boiling
point of water.
Identifying Prokaryotes
Prokaryotes are identified by characteristics such as
shape, chemical nature of their cell walls, the way they
move, and the way they obtain energy.
Shapes
 bacilli are rod shaped
 cocci are spherical
 Sprilla spiral and corkscrew
Identifying Prokaryotes
Cell Walls - 2 different types
Gram Staining is used to tell them apart
Violet (primary stain) is applied first. It stains the
peptidoglycan cell wall. The alcohol treatment wash out
the stain. Gram positive bacteria have thick
peptidoglycan walls which retains the dark col0r.
Gram Negative bacteria have thinner walls inside an
outer lipid layer. Alcohol dissolves th lipid and removes
dye from the walls of the bacteria. Red (counter stain)
makes bacteria appear pink and light red.
Movement of the Prokaryotes
Some prokaryotes do not move. Others are
propelled by flagella, whiplike structures use
for movement. Prokaryotes lash, snake or
spiral forward, other glide slowly along a layer
of slimelike material they secrete.
Metabolic Diversity
Most prokaryotes are heterotrophs, they get
their energy from consuming organic
molecules made by other organisms.
Autotrophs make their own food from
inorganic molecules.
Heterotrophs take in organic molecules for
both energy and supply of carbon called
chemoheterotrophs.
Metabolic Diversity
Staphylococcus aureus releases toxins that
cause food poisoning.
Photoheterotrophs are photosynthetic and
use sunlight for energy. They also take in
organic compounds as a carbon source.
Autotrophs
 Use light energy to convert carbon dioxide and water
to carbon compounds and oxygen in a process similar
to that used by green plants.
 Found in surfaces of lakes, streams, and oceans.
Cyanobacteria is a bluish pigment and chlorophyll a
the key pigment in photosynthesis. They are found in
freshwater, salt water, and even on land. Cyanobacteria
is the first species to recolonize the site of a natural
disaster such as volcanic eruption.
Chemoautotrophs
 performs chemosynthesis
 makes organic carbon molecules from carbon dioxide
 do not require light as a source of energy
 use energy directly from chemical reactions involving
ammonia, hydrogen sulfide, nitrites, sulfur and iron
 some live deep in the darkness of the ocean.
They obtain energy from hydrogen sulfide gas that flows
from the hydrothermal vents on the ocean floor.
Growth and Reproduction
Binary Fission is when the bacterium nearly double in
size, it replicates its DNA and divides in half producing 2
identical daughter cells. It does not involve the exchange
or recombination of genetic information. It is an asexual
form of reproduction.
Conjugation is the exchange of genetic information by
a process. A hollow bridge forms between 2 bacterial
cells. The genes moves from one cell to the other. The
transfer of genetic information increases genetic
diversity in populations of bacteria.
Spore Formation
Spore Formation is when growth conditions become
unfavorable many bacteria will form structures called spores.
Endospores is when bacterium produces a thick internal
wall that encloses DNA and a portion of its cytoplasm.
Spores can remain dormant for months or even years while
waiting for more favorable growth conditions.
When conditions improve the endospore will germinate and
bacterium will begin to grow. They can survive harsh
conditions including extreme heat, dryness of lack of
nutrients.