Download 3 CellStructure I

Anatomy of Prokaryotes and Eukaryotes
• Prokaryotic Cell Structure
• Cell size, shapes, and arrangements
• Parts of a Prokaryotic Cell
• Glycocalyx: slime layer or capsule
• Fimbriae and sex pilus, flagella
• Cell wall and plasma membrane (g+, g-, mycobacteria, archaebacteria)
• Plasma membrane and material transport; osmosis
• Nuclear Area (Nucleoid), Plasmids, Ribosomes
• Endospores
• Eukaryotic Cell Structure
• Cytoplasm (open streets and city squares)
• Nucleus (library)
• Ribosomes (construction factories)
• Internal membrane System: ER, Golgi, Lysosomes
• Mitochondria (power station)
• Chloroplasts (food synthesis factory)
• Cytoskeleton (pulling ropes,& lumber)
Comparison of Prokaryotic and Eukaryotic Cells
Prokaryotic Cell Morphology
• Average size: 0.2 -1.0 µm  2 - 8 µm
• Basic shapes:
Cocci
Bacilli (rods)
Spirilla
Cellular Arrangements
Anatomy of Prokaryotes and Eukaryotes
• Prokaryotic Cell Structure
• Cell size, shapes, and arrangements
• Parts of a Prokaryotic Cell
• Glycocalyx: slime layer or capsule
• Fimbriae and sex pilus, flagella
• Cell wall and plasma membrane (g+, g-, mycobacteria, archaebacteria)
• Plasma membrane and material transport; osmosis
• Nuclear Area (Nucleoid), Plasmids, Ribosomes
• Endospores
• Eukaryotic Cell Structure
• Cytoplasm (open streets and city squares)
• Nucleus (library)
• Ribosomes (construction factories)
• Internal membrane System: ER, Golgi, Lysosomes
• Mitochondria (power station)
• Chloroplasts (food synthesis factory)
• Cytoskeleton (pulling ropes,& lumber)
Glycocalyx
• Outside cell wall
• Usually sticky: provides
for attachment and
protection
• Types
• A capsule is
neatlyorganized
gelatinous layer
• A slime layer is
irregular & diffuse
• Extracellular
polysaccharide allows cell
to attach
• Capsules prevent
phagocytosis
Figure 4.6a, b
Flagella
• Filaments outside cell wall
• Made of chains of flagellin
protein
• Attached to a protein hook
• Anchored to the wall and
membrane by the basal
body
Flagellar rotation is powered by the
hydrogen ion gradient (proton
motive force)
H+
+ H+
H
H + H+
H+
+
H
H+
H+
H+
H+
H+
H+
H+
Figure 4.8
Flagella Arrangement
Figure 4.7
Axial Filaments
• Endoflagella
• In spirochetes
• Anchored at one end
of a cell
• Rotation causes cell
to move
Figure 4.10a
Fimbriae and Pili
• Fimbriae allow for
attachment of cell to
a substrate
• Pili are used to
transfer DNA from
one cell to another in
conjugation
Figure 4.11
Anatomy of Prokaryotes and Eukaryotes
• Prokaryotic Cell Structure
• Cell size, shapes, and arrangements
• Parts of a Prokaryotic Cell
• Glycocalyx: slime layer or capsule
• Fimbriae and sex pilus, flagella
• Cell wall and plasma membrane (g+, g-, mycobacteria, archaebacteria)
• Plasma membrane and material transport; osmosis
• Nuclear Area (Nucleoid), Plasmids, Ribosomes
• Endospores
• Eukaryotic Cell Structure
• Cytoplasm (open streets and city squares)
• Nucleus (library)
• Ribosomes (construction factories)
• Internal membrane System: ER, Golgi, Lysosomes
• Mitochondria (power station)
• Chloroplasts (food synthesis factory)
• Cytoskeleton (pulling ropes,& lumber)
Cell Wall
• Prevents osmotic lysis
• Made of peptidoglycan (in eubacteria)
Figure 4.6a, b
Peptidoglycan: Rows of Polysaccharide Crosslinked By Peptide Chains
Figure 4.13a
Gram Positive vs. Gram Negative Cell Envelope Anatomy
Penicillin blocks
cell wall crosslinking and
causes mostly
gram positive
bacteria to lyse
Lysozyme breaks NAG-NAM linkage and removes
cell walls from gram positive and negative cells
Gram Stain Mechanism
•
•
•
Steps
1.
Primary stain (CV)
2.
Mordant (iodine)
3.
Decolorizer (ethanol-acetone)
4.
Counterstain (safranin)
Gram-positive
•
Alcohol dehydrates
peptidoglycan
•
CV-I crystals do not leave
--> purple
Gram-negative
•
Alcohol dissolves outer
membrane and leaves
holes in peptidoglycan
•
CV-I washes out -->
pink
Differential Stains: Gram Stain
Figure 3.10b
Atypical Cell Walls
•
Mycobacteria (e.g. Mycobacterium
tuberculosis, M. leprae) have cell
envelopes similar to gram negatives
but employ waxy mycolic acid
instead of LPS in outer membrane
•
Mycoplasmas (e.g. Mycoplasma
pneumoniae)
•
•
Lack cell walls
•
Include unique mycosterols in
plasma membrane add strength
Archaeans (two main
configurations)
1. Wall-less
2. Walls of pseudomurein (uses
NAT instead of NAM and
different amino acids for crossbridges)
Differential Stains: Acid-Fast Stain
• Cells that retain a basic stain (carbolfuchin)in the presence of acidalcohol are called acid-fast.
• Non–acid-fast cells lose the basic stain when rinsed with acidalcohol, and are usually counterstained (with a different color basic
stain) to see them.
• Important in identifying Mycobacterium species that cause leprosy
and tuberculosis
Figure 3.11