Prokaryotic Cell Structure and Function
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Transcript of Prokaryotic Cell Structure and Function
Prokaryotic Cell Structure and Function
Size of Bacteria
• Average bacteria 0.5 - 2.0 um in diam.
– RBC is 7.5 um in diam.– Pulopiscium fishelsoni, bacillus (80µm in
diameter and 200-600 µm long)– Thiomargarita namibiensis, sperical (100-
750 µm in diameter.)
Shapes of Bacteria
• Coccus• Bacillus• Coccobacillus• Vibrio• Spirillum• Spirochete
Spherical BacteriaAn average coccus is about
0.5-1.0 micrometer (µm) in diameter.
A. Division in one plane.
• Diplococcus: cocci arranged in pairs
• Streptococcus: cocci arranged in chains
• Streptococcus pneumoniae,
• Streptococcus pyogenes,
Spherical Bacteria
B. Division in two planes.
• tetrad: cocci arranged in squares of 4
C. Division in three planes
• Sarcina: cocci in arranged cubes of 8
sarcina
Spherical Bacteria
D. Division in random planes
• Staphylococcus: cocci arranged in irregular, often grape-like clusters
Rod-Shaped Bacteria
• Diplobacillus
• Coccobacillus
• Streptobacillus
Spiral-Shaped Bacteria
• Spirochete
• Spirillum
Cell Structures
• Cell Membrane
• Cytoplasm
• Cell Wall
• Components external to cell wall – Flagella – Pili– Capsule/ Slime layer
Cell Membrane
• Hydrophobic Proteins
• Bilayer Phospholipid – Triclosan-enoyl transferase
• Hopanoids
Membrane proteins
• Structural support
• Detection of environmental signals– ToxR- Vibrio cholera
• Secretion of virulence factor and communication signals– NodI and NodJ-Rhizobia
Membrane lipids
• Phosphoryl heads– Negative-phosphatidate
• Phosphatidylglycerol• Cardiolipin
– Positive-Phosphatidylethanolamine• DNA interaction
• transporter protein
• Fatty acids– Saturated straight chain (6-22) – Unsaturated
• Oleic acid (cis)– Cyclopropane