Transcript Functional Anatomy of Prokaryotic Cells

Functional Anatomy of
Prokaryotic Cells
Chapter 4
Arrangements of Cocci
Arrangements of Cocci
Arrangements of Bacilli
Arrangements of Bacilli
Arrangements of Spiral Bacteria
Arrangements of Spiral Bacteria
Anatomy of Prokaryotic Cells
• Glycocalyx: Capsule or Slime layer?
• A. Components: sticky gelatinous
polymer of polysaccharide and
protein found on the outside of the cell
wall.
• 1. Thick, highly organized, and
solidly fixed to the cell wall, it is
referred to as a capsule.
• 2. Thin layer, unorganized, loosely held
to the cell wall it is referred to as a
slime layer.
Glycocalyx
B. Function:
1. Attachment: Allows the bacteria to attach to
surfaces in its natural environment.
2. Protection:
1. Protect against dehydration
2. Protects against phagocytosis
3. Nutrition:
1. Keeps nutrients in the cell.
2. May be a source of nutrition
A. Components:
1. Filament: composed of
proteins called flagellin
that form the long hairlike
structure that sticks out of
the cell. (Not enclosed
w/in the plasma
membrane in
prokaryotes)
2. Hook: wide structure that
holds the filament and
turns it like a propeller
3. Basal body anchors
flagellum to the cell wall
and plasma membrane.
Flagella
B. Function of Flagella
Propulsion and taxis
(chemotaxis)
1. Runs and
tumbles
2. Receptors for
attractants and
repellant
Types of Flagella Arrangement
• Monotrichous: a single flagellum at one
end
• Amphitrichous: a single flagellum at both
ends of the cell
• Lophotrichous: two or more flagella at one
or both ends of the cell.
• Peritrichous: flagella all over the cell.
Monotrichous
(single flagellum at one end)
Amphitrichous
(a single flagellum at both ends of the cell)
Lophotrichous
(two or more flagella at one end of the pole)
Peritrichous
(flagella all over the cell)
Axial filaments
1. Found only in
spirochetes
2. Axial filament is
located between the
outer sheath and the
cell wall
3. Contraction of the
axial filament results
in spiral motion of
spirochetes
Fimbriae
A. Composition:
Fimbriae are hairlike
appendages made out
of pilin (shorter, and
thinner than flagella)
B. Function
Used for attachment
and colonization of host.
VI Pili
A. Composition:
Pili are made out of pilin
protein to form a single long
shaft connecting two bacteria
together.
B. Function:
To exchange DNA between
bacteria