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Prokaryotic profiles
When did prokaryotes first appear?
What are the basic differences?
Characteristic
Prokaryotes
Eukaryotes
# of cells
Unicellular
Uni or multi
DNA shape
DNA is circular, no
histones
DNA in chromosomes
w/histones
DNA location
Free in cell
In PM-bound nucleus
True organelles?
No
Yes
Ribosomes
70S
80S
First amino acid in
protein
Formylmethionine
Methionine
Cell wall?
Yes-peptidoglycan
No (animalia); Yes (plantae—
cellulose); Fungi (chitin)
Reproduction
Binary fission three ways to
Mitosis
reproduce
How do prokaryotes compare in size with
other microorganisms?
How do I describe their shapes?
Is a species always the same shape?
• Generally, yes
– Monomorphic
– however,
environment can
alter
• Some are
pleiomorphic
Photo from: uhavax.hartford.edu/bugl/Yersinia-pestis.jpg
The parts
Starting from the outside and working
inward
What’s outside the cell wall?
• Glycocalyx
– Carbohydrates and/or
peptides
– Viscous
– Can protect bacterium
– Some help cells attach
• Teeth: Streptococcus mutans
• Capsule
– Organized
– Firmly attached to cell wall
• Slime layer
– Unorganized
– Loosely attached
What are flagella?
•
•
•
•
•
Singular = __________
Monotrichous
Amphitrichous
Lophotrichous
Peritrichous
What do flagella do?
• Run and
tumble
• Swarming
• Allow for
taxis
– Chemotaxis
– Phototaxis
• dancing bacteria!
What are axial filaments?
• AKA
periplasmic
flagella
– Fibril
bundles
that spiral
around cell
What’s the difference between fimbriae and pili?
• Found primarily on
gram-negative
bacteria
• For attachment, not
movement
• Pilin protein
• Fimbriae (fimbria,
singular)
– Attachment
• E.g. to mucosal
membranes
• Pili (pilus,
singular)
– For DNA
exchange only
What’s in the cell wall?
• Peptidoglycan (PPG)
– AKA murein
– NAG-NAM
disaccharide
• NAG = Nacetyleglucosamine
• NAM = Nacetylemuramic acid
– Lysozyme disrupts
NAG-NAM bond
• If lysis doesn’t occur,
cell is called a
protoplast
– Linked with
tetrapeptide
• Penicillin disrupts 
lysis
• penicillin killing cells
What’s in the
cell wall?
• Gram positive bacteria
– Many PPG layers
– Teichoic acids
• Different types
• Used for antigenic specificity tests
What’s in the
cell wall?
• Gram negative bacteria
– One or few PPG layer(s)
– Outer membrane: lipopolysaccharides (LPS), lipoproteins,
phospholipids
• Periplasm separates LPS from the PM (PPG is in periplasm)
• Provides barrier to some antibiotics, digestive enzymes
• Porins allow for access into cell
– LPS used for specific antigen tests to I.D. species
What does a side-by-side comparison look like?
More comparison
How does this relate to gram staining?
• Hint: What does the LPS layer covering the gram negative cell do to it?
What are atypical cell walls?
• Mycoplasma
– Smallest known
independent bacteria
– No cell walls
– Often mistaken for
viruses
– PM has sterols to
prevent lysis
• Mycobacteria
– Mycolic acid in cell wall
• Hydrophobic
• Acid-fast stain
identifies
• Tuberculosis, leprosy
• Archaea
– Some have cell walls but
not with PPG
– Pseudo-murein
Mycoplasm pneumoniae
What happens if the cell wall is
damaged?
• Lysozyme lyses gram positive, but usually does not harm gram
negative to the same extent
– Why?
• Protoplast: gram positive
• Spheroplast: gram negative
• Osmostic lysis
– If placed in a hypotonic environment
What’s inside the cell wall?
• Plasma membrane
– Phospholipid bilayer
– Fluid mosaic theory
•
•
•
•
Segregates DNA during binary fission
Secretes enzymes to make PPG, teichoic acid
ATP production
Selective permeable membrane…
– Active vs. passive transport
What kinds of passive transport exist?
• Simple diffusion
– For small, lipid-soluble
substances
• Osmosis
– Water movement via
diffusion
– Happens whenever
difference in
concentration across PM
– Note: water often moves
because solutes can’t
• Because PM is only semipermeable
Simple diffusion
What do you think will happen?

A. Left side increases with water
B. Right side increases with water
C. No net movement of water
Click here to show
what actually happens:
answer animation
What is osmosis?
• Water concentration depends on number of solutes in it
– Hypertonic
– Isotonic
– Hypotonic
• Water moves down its concentration gradient until
osmolarity is equal
What do you think will happen?
For each, choose from
A. No net change
B. cell swells C. cell shrinks
10%
glucose
20% glucose
Distilled water
10% glucose
What is facilitated passive diffusion?
• Proteinassisted
diffusion
– Transporters
or carriers
• Amino
acids,
glucose
– Channels
(AKA
“pores”)
• Most are
gated
(usually
closed)
What is active transport?
• Movement of solute against gradient
– Can you think of examples of where this might happen in your
body?
• Requires energy b/c moving against gradient
– From ATP
• Proteins sometimes called “pumps”
What is group translocation?
• Type of active transport
– Only in prokaryotes
– Chemically altered as it is pulled across PM into cell
• Once inside, cannot exit
• E.g. glucose phosphorylation
• Animation
What is the cytoplasm?
• Eukaryotes
– Cytosol +
organelles
• Prokaryotes: all
stuff inside cell
– 80% water +
nuclear area,
ribosomes,
inclusions
(storage areas)
What is the nuclear area?
• AKA nucleoid
• Circular, doublestranded DNA
– Called bacterial
chromosome
• Plasmid
– Also double-stranded
DNA
– Independent replication
– Associated with PM
proteins
– Can gain or lose without
killing cell
– Can provide resistance to
antibiotics, etc.
What are ribosomes?
• Manufacture proteins
• Two subunits
– Each with proteins and rRNA
– 70S ribosomes (smaller than eukaryotes)
• 50S and 30S subunits
• Eukaryotes = 80S ribosomes (60S + 40S)
What are inclusions?
• Storage areas
• Metachromatic
granules
– Collectively called
volutin
• Phosphate reserve
for making ATP
• Polysaccharide
granules
– Iodine stain shows
these
• Others with
– Lipids, sulfur
granules, etc.
– Magnetosomes:
iron oxide
What are
endospores?
• Usually gram-positive
bacteria
– Not a reproductive structure
– Survival structure for bad
times
• Inside PM
– Form thick walls
– Tolerate high heat,
dehydration, poisons,
radiation
– Can survive up to 25 to 40 M
years!!!!!!!!
– Problem for food industry!
• Botulism
How are spores formed?
• Sporogenesis
– Usually resource
scarcity triggers
• Carbon, nitrogen, etc.
– Spore is highly
dehydrated
• Vegetative state
• Favorable
conditions
– Germination
Prokaryotic domain
What are taxonomic groups of bacteria?
• Gracilicutes
– Gram -
• Firmicutes
– Gram +
• Tenricutes
– (no cell cell—e.g. mycoplasmas)
• Mendosicutes
– (Archaebacteria)
What’s the difference between a species
and a strain?
• Species: share similar pattern of traits
• Subspecies/strain/type: same species
with differing characteristics
• Serotypes: unique antibody response in
host
What about unusual bacteria?
• Rickettsias
– Parasitic, gram
negative
– Arthropod
vector
– RMSF
– Q Fever
What about unusual bacteria?
• Chlamydias
– Parasitic
– No vector
Photo from: http://www.sexually-transmitted-diseases.info/images/std_chlamydia.jpg
What about Mendosicutes?
• No PPG
• 70S
• Extremophiles
– Halophiles
– Thermophiles
– Methanophiles
Photo from: http://people.westminstercollege.edu/faculty/tharrison/gslfood/studentpages/pinkwater2.JPG