Cellular Structure
Chapter 4
Eubacteria
Eukarya
Archaea
Monera (defunct)
Eubacteria
Eukarya
Archaea
Animalia
Fungi
Plantae
Protista
Bacterial Structure
Outwardly, there is little to go
by in bacterial structure
Bacteria may be of various
shapes (morphologies)
Coccus = Spherical
Bacillus = Rod
Spiral = Spiral
Pleomorphic =
Varied, Undefined
On a microscopic level there
are layers of structure.
Glycocalyx = Outer
Coating.
Flagella = Motive
structures
Fimbriae and Pili =
Attachment
Bacteria are divided into two
large groups based on overall
cellular structure
Gram Positive vs. Gram Negative
Gram Identity is about cell
structure more than staining
Gram Positive =
Single Membrane
Gram Negative =
Double Membrane
EXCEPTION
Mycobacterium
EXCEPTION
Mycoplasma
Even exceptions to normal
Gram staining can be
classified by their overall
structure and genetics.
Internal structure in bacteria
is limited, but organized.
Specialized internal structures
are found in some bacteria.
Endospores
G+ structure to
go dormant.
Magnetosomes
Magnetite crystals
for alignment
Storage Granules
PHB Energy
Storage
Eukarya Structure
Eukarya externally lack the
complexity of Bacteria but are
more internally structured
There are three classes of
organelles.
Non-membrane
Bound
Ribosomes,
flagella, etc.
Endomembrane
System
Nuclear Membrane,
ER, etc.
NonEndomembrane
Membrane-Bound
Mitochondria and
Plastids
Non-Membrane Organelles
A Note on Evolution
Ribosomes
Public Domain - PDB
Cytoskeleton
Endomembrane System
Nucleus
Cell Nuclei in
HeLa Cells
Public Domain Image-Wikipedia
The Nucleus has numerous
functions
Contains the
DNA of the Cell
Controls access
to the DNA
Regulates division
of the DNA
Endomembrane System
Wikimedia Commons
Mitochondria and Plastids
Mitochondria
Chloroplasts
These organelles share a
number of unique characteristics
Internal DNA
Each possess a
small circular
piece of DNA
Ribosomes
Each possess
ribosomes internal
to their structure
Binary Fission
Both reproduce
independent of the
cell cycle.
Endosymbiotic Theory
Aerobic Eubacteria
Photosynthetic Eubacteria
Protoeukaryote
Aerobic Eukaryote
Photosynthetic
Eukaryote
Various lines of evidence
support this theory.
Organelle ribosomes
more closely resemble
bacterial ribosomes
than eukaryotic
ribosomes.
DNA of
Mitochondria is
closely related to
Rickettsia bacteria.
DNA of Chloroplasts
is closely related to
blue-green
photosynthetic
bacteria.