Transcript Chapter 4

Chapter 4
Functional Anatomy of
Prokaryotic and Eukaryotic
Definition of “prokaryotic”
Refers to organisms, typically 1-celled,
having cells which:
– lack a nucleus
– lack membrane-bound
– contain 1 chromosome
– may contain extra-chromomal
DNA (plasmids)
– contain 70S ribosomes
– contain peptidoglycan cell
Prokaryotic vs. Eukaryotic cells
Kingdom Monera divided into three major groups or Subkingdoms
Kingdom Monera
Bacterial cell size, shapes and arrangements
• 2.0 – 10.0 uM in length
• Eukaryotic cells ~10x larger
• 3 common morphologies
– bacillus = rod-shaped
– coccus = spherical shaped
– spirillum = spiral shaped
• Many arrangements
– diplo– strepto– Staphylo***spirochetes**
Bacterial morphologies
• Morphology can be
used as an initial
• However, shape can
change in some bacteria
depending on environs
– “pleomorphic” cells
Bacterial ultrastructure
1) Cell wall structure
• Alternating NAM & NAG amine sugars produce
layers of block units
– NAM = n-acetylmuramic acid
– NAG = n-acetylglucosamine
Make up peptidoglycan
• Layers connected by tetrapeptide chains linked to
• Penta-glycine interbridges connect tetrapeptides in
Gram + cells (sensitive to penicillin)
• Direct peptide bonds connect tetrapeptides in
Gram – cells (not sensitive to penicillin)
Alternating NAM-NAG with
tetrapeptide connections
Gram positive cell wall structure
Ok, not too bad – now for something completely different –
Gram negative cell walls!    
Gram negative cell wall structure
Gram neg. cell walls are composed of peptidoglycan AND an
outer membrane; it is multi-layered!!
Gram negative LPS*
• *Lipopolysaccharide contains 3 parts:
– Antigen O – can change shape in dif’t environs
– Core polysaccharide – contains neg. charge
– Lipid A – also called ‘endotoxin A’; released
upon cell death and can have toxic affect on
nearby cell membranes
Gram pos. vs Gram neg cell walls
Gram +
• Thick peptidoglycan
– 20-80 nm thick
• Retains CV-I complex
of Gram stain
• Teichoic acid anchors
cell wall to cell
membrane and imparts
a negative charge
– Glycerol-P polymer
Gram -
• Two part structure
– Thin peptidoglycan
(10-20 nm)
– Outer membrane
• Outer membrane
contains LPS
• LPS imparts a
negative charge
The Gram stain
2) Bacterial flagella
• Composed of: 1) basal body, 2) filament, 3) hook
• Basal body connects to cell wall and to cell membrane
• Uses ATP to spin
Arrangements of flagella
Bacteria are hampered to some
extent by flagellar rotation