AP Biology Chapter 27: Prokaryotes 12
Concept 27.1: Structural, functional, and genetic adaptations contribute to prokaryotic success
 Cell-Surface Structures:
 Quintessential towards prokaryotic survival; different surface structure and structural arrangement will
protect the unicellular organism’s organelles from the external environment.

Gram Positive:

The simplicity of the surface structure allows it to be easily targeted and destroyed.
 Gram Negative:


The complexity of the cell wall and the lipopolysaccharides make Gram-Negative bacterial more
resistant to resistant to drugs and toxic.
Fimbriae and Capsules are structural formations on the surface of cells that allow them to adhere to certain
surfaces.
 Motility:
 Prokaryotes use flagella for motility.
 Taxis – cellular movement towards or away from a given stimulus.
 Internal and Genomic Organization:
 The infolding of plasma membranes in prokaryotes is similar to the energy producing organelles of

eukaryotic cells: chloroplasts and mitochondria.
The unbound DNA of prokaryotes reside in the nucleoid region. Prokaryotic DNA also exists as plasmids,
which may be transferred between prokaryotes.
 Reproduction and Adaptation:
 Because prokaryotes are able to divide every 1-3 hours, their accumulation of beneficial mutations are
much more common than in eukaryotes.

Endospores, are resilient, dehydrated shells that prokaryotes may store their genetic information
into if they experience unsuitable conditions.
Concept 27.2: Variety of nutritional and metabolic adaptations in Prokaryotes
AP Biology Chapter 27: Prokaryotes 12
 Obligate aerobes and anaerobes require O2 and CO2, respectively, to survive, while facultative anaerobes can survive
in either conditions, but would prefer an O2 environment.
 Certain prokaryotes obtain food by fixing inorganic nitrogen through nitrogen fixation.
 Metabolic Cooperation occurs in single bacterium or entire colonies where more than one metabolic process occurs
and is the reason that some prokaryotes exist in close proximities.
Concept 27.3: Prokaryotic Phylogeny:


Through comparing small-subunit ribosomal RNA, Woese classified a type of prokaryote as Archaea as they exhibit a
combination of bacterial and eukaryotic traits.
 Archaea extremohiles are prokaryotic organisms that thrive in extreme conditions.

Extreme thermophiles exist in very hot environments.

Extreme halophiles exist in very saline environments.
 Methanogens are unique archaea that derive their energy by using CO2 to oxidize H2 and release methane
as a waste produce.
Major Groups of Bacteria:
 Proteobacteria:
A diverse group of gram-negative bacteria.
 Chlamydias: Parasitic cell that lack peptidoglycan.
 Spirochetes: Obtain motility through rotating flagellum-like filaments.
 Gram-Positive Bacteria: An equally diverse group of bacteria.
 Cyanobacteria: The only prokaryote that carries out oxygen-generating photosynthesis.
Concept 27.4: Prokaryotes play crucial roles in the biosphere
 Relationship between organisms:
 Symbiosis is the ecological relationship between organisms of different species.
 The larger of the two is called the host, while the smaller is called the symbiont.
 In mutualism, both organisms benefit.
 In commensalism, one organism benefits while not harming nor benefiting the other.
 In parasitism, the parasite organism benefits at the expense of the host.
Concept 27.5: Impact of Prokaryotes on humans


Negative Impacts:
 Exotoxins - Toxins secreted by prokaryotes
 Endotoxins - Toxins that coat the outer membrane of gram-negative cells, otherwise known as the
lipopolysaccharide layer. These toxins are only released once the cell has been destroyed and its cell wall
broken down.
Positive Impacts:
 Bioremediation – The use of micro-organisms to remove pollutants from the air, water, and soil.