Prokaryotic Cell Structure
Chapters 3 and 11
Eukaryotic cell structure
-- you should review from Biol 131
Archeal cell structure
– not much different than Bacteria
Inclusions
Ribosome
Cytoplasm
Nucleoid
Glycocalyx
Bacterial Classification
-- you are not responsible for the
details presented in Chapter 11, but
should read about different types of
bacteria presented in class
Flagellum
Cell wall
Cytoplasmic membrane
We will be discussing classification
again as part of bacterial metabolism
Bacteria
1
Why are bacteria so small?
Size affects ‘surface to volume’ ratio
Advantages of large S/V:
diffusion rates
metabolic rates
reproductive rates
Limits to size reduction?
‘defective’ bacteria
Really big bacteria?
-- Epulopiscium fishelsoni
Epulopiscium web site
http://www.micro.cornell.edu/cals/micro/research/labs/
angert-lab/epulopiscium.cfm
Bacteria
2
Classification of bacteria is ‘murky’
A “Muddle in the Middle”
Few distinctive characteristics
Genetically promiscuous
-- “horizontal” gene transfer
Traditional classification:
anatomical features
staining characteristics
metabolic properties
Newer approach
Genetic analysis
Bergey’s manual is the ‘Bible’
Bacteria
3
Classification based upon
anatomical features
3 common shapes
-- coupled with staining properties
e.g.,
“Gram-pos cocci”
“Gram-neg bacilli”
Some unusual shapes also:
Bacteria
4
Classification based upon
anatomical features
-- more info about these is in Chap 11
Other unusual bacteria
Spirochetes
Cell wall-less (mycoplasmas)
Stalked
Filamentous
Streptomyces
Myxobacteria fruiting bodies
Bacteria
5
External Anatomical Structures
-- Bacterial Flagella
Prokaryotic vs eukaryotic
Arrangements
monotrichous
lopho-
amphi-
peri-
How do we know movement
is rotational?
Flagella movement
Flagella Details
Bacteria
6
How do flagellated
bacteria move?
‘Run and Tumble’ pattern
Chromatium motility
Bacterial movement
Bacteria
7
Spirochetes
-- very strange structure
-- e.g., Borrelia, Treponema
Axial filaments
Outer sheath
Motility
Borrelia Movement
Spirochetes
Bacteria
8
Fimbriae and Pili
Fimbriae
adhesion to surfaces
Pili (pilus)
genetic recombination
other functions?
Bacteria
9
The glycocalyx
Functions
Biofilms
-- adherence
-- virulence
Prevent desiccation
Composition
Capsule layers
vs
Slime layers
“xantham gum”(Xanthomonas)
S. Pneumo evasion
Bacteria
10
Cell wall structure
Hans Christian Gram -- 1884
-- Crystal violet
Gram positive structure
-- thick layer of peptidoglycan
Gram negative structure
-- inner vs outer membranes
-- thin layer of peptidoglycan
-- lipopolysaccharides and endotoxins
Acid fast staining
Lipopolysaccharide
(LPS) layer
-- Mycobacterium
Outer membrane
Peptidoglycan
Effect of penicillin
Cell membrane
Bacteria
11
Cell Membrane
Structure
Review basic membrane
structure from Biol 131
-- Phospholipid bilayers
-- Membrane proteins
-- Membrane fluidity
Membranes of
thermophilic archaebacteria
Bacteria
12
Components of prokaryotic cytosol
No membrane-bound organelles
Cytoplasm
Ribosomes
DNA
Inclusions
food or waste storage
Bacteria
13
Endospores
Clostridium & Bacillus
Formation and regrowth
Special properties?
-- desiccated
-- DNA binding proteins
-- Ca-dipicolinic acid
Endospore formation
Magnetotactic bacteria
-- possess magnetosomes
Magnetotactic Bacteria
Bacteria
14