Prokaryotes
Think!!!!: What is the study of microorganisms called?
What is the study of bacteria called?
Remember what a
PROKARYOTE IS!!!
1. A unicellular organism that lacks
a________________.
2. There are 3 domains of life:
________________ ________________
__________________. Of the three,
prokaryotes are classified in the
____________ or _____________ domain.
How are Bacteria and Archaea same/
different?
Similarities
 Small (microscopic)
 Lack nuclei
 Have cells walls
Differences
 Archaea live in very HARSH/ EXTREME
environments
 Cell walls of bacteria have peptidoglycana polymer of sugars and amino acids that
surrounds the cell membrane while archaea
DO NOT!
 Archaea contain different lipids than
Bacteria in their cell membranes
 DNA sequences of archaea are closer to
that of eukaroyotes than bacteria (making
them more closely related to eukaryotes).
3 Ways to tell prokaryotes
apart…
1. Size/ Shape
2. How they move
3. How they obtain/
release energy
Shapes
1. Bacilli- rod
shaped
2. Coccus (cocci)spherical
3. Spirilla (spirillum)corkscrew/ spiral
shaped
Energy Capture
by Prokaryotes
1. Heterotroph- “_______ _______” Take
in organic molecules from
environment or other organisms to use
as both energy and carbon supply
2. Photoautotroph- “_____ ______
______” Use light energy to convert
carbon dioxide into carbon
compounds
3. Photoheterotroph- “ _________
________ _______” Like basic
heterotrops but also use light energy
4. Chemoatutroph- “ _______ _______
_________” Use energy released by
chemical reactions involving
ammonia, hydrogen sulfide, etc.
Energy Release by
Prokaryotes
1. Obligate aerobe- “________
______” Energy released by cellular
respiration; need a steady supply
of oxygen
2. Obligate anaerobe- “_____ ___
_________ _________” Energy
released by fermentation (die in
the presence of oxygen)
3. Facultative anaerobe- “_______
______ _______ ____ _______”
Energy released in either cellular
respiration or fermentation as
necessary
Prokaryote growth
Binary fission:
1. Prokaryote grows to
nearly double its size
2. Replicates DNA
3. Divides in half
producing 2 IDENTICAL
CELLS!
If conditions for prokaryotes become
unfavorable…
Many bacteria can form an endospore! It’s a thick
internal wall that encoloses the DNA and a portion of the
cytoplasm. Bacillus anthracis (anthrax) is one such
bacterium that can do this!
Prokaryotes reproduce asexually…so how
do they evolve???
 2 ways!
 Mutation- random change in DNA
 Conjugation- exhanging genetic information by forming a hollow bridge
between two bacterial cells; genetic material (in the form of a plasmid) moves
from once cell to the other
 Carry genes that enable bacteria to survive in new environments or resist
antibiotics
 Increases genetic diversity in populations of prokaryotes
3 Roles!
Importance of
Prokaryotes
1. Decomposers- break down dead
organisms to supply raw materials for
living things…if these materials were not
recovered when organisms died, life
could not continue. Also, very helpful in
sewage treatment!
2. Producers- photosynthetic prokarytoes
(like cyanobacterium) provide food
chains everywhere as producers of food
and biomass
 Prokaryotes are ESSENTIAL in maintaning
every aspect of the ecological balance of
the living world. Some species also have
specific uses in human industry…
3. Nitrogen Fixers- Nitrogen is essential for
plant growth, but plants can’t take it out
of the atmosphere by themselves.
Nitrogen fixation is the process of
converting nitrogen gas into ammonia.
Ammonia can then be converted to
nitrates that plants use. Nitrogen-fixing
bacteria and archaea provide 90% of the
nitrogen used by other organisms! (i.e.
Rhizobium lives on plant roots)
Human uses!
1. Food!
2. Digest petroleum
3. Remove human made waste products and poisons
from water
4. Synthesize drugs/ chemicals
Bacteria and Disease
What you need to know…
Pathogen
 A pathogen is a microorganism (virus or prokaryote) that causes
disease
 Fun fact: Louis Pasteur was the first to prove that bacteria do indeed cause disease (germ
theory)
How do Bacteria
cause
disease???
2 ways:
1. Destroying living
cells in the host
2. Releasing
chemicals
(called toxins)
that upset
homeostasis
How to control
bacterial
growth
1. Physical removal –
washing hands helps
dislodge bacteria and
viruses
2. Disinfectants- chemicals
3. Food storagerefrigerator/ freezer
4. Food processingboiling/ steaming/ frying
5. Sterilization by heatabove 100 degrees
Celsius
Preventing/ Treating Bacterial Diseaes
 Prevention: Vaccines!
 A preparation of a weakened  Treatment: Antibiotics!
or killed pathogen or
 Block the growth and
inactivated toxins
reproduction of bacteria by
 Stimulates immune system
disrupting proteins or cell
processes that are specific to
bacterial cells without harming
host cells
 For Bacteria only!!!
 i.e. Penicillin, Azithromycin,
Tetracyline