BIO 315 Lecture Notes - Lecture 3: Periplasm, Tubulin, Inclusion Bodies
2 Jun 2018
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Lecture 3: Bacterial Morphology and Taxonomy
Size of Bacteria Varies Greatly
• Usually smaller than eukaryal cells (bacteria are often 0.5-5µm in length)
• Small eukaryal cells are usually >5µm in diameter
• Mycoplasma gallicepticum is a parasitic bacterium which lives in the primate bladder and lack a
cell wall; smallest known organism capable of independent growth and reproduction
• Largest bacteria ever discovered are thiomargarita namibiensis and are found in the ocean
sediments
Morphology of Bacterial Cells
• Bacteria take on many shapes
• Spherical (S. coccus, pl. cocci)
• Rod-shaped (S. bacillus, pl. bacilli)
• Curved rod (S. vibrio, pl. vibrios)
• Spiral (S. spirillum, pl. spirilla)
o Ex: borrelia which cause Lyme disease
• Pleiomorphic (varied shapes)
• Oval-shaped: coccobacillus; ex: E-coli
• Arrangement:
• Alone: single
• Arranged in grape bunch fashion: staphylo
• Arranged in a linear fashion: strepto
• Bacteria can assume "multicellular" organizations
• Hyphae: branching filaments of cells
• Mycelia: tufts of hyphae
• Trichomes: smooth, unbranched chain of cells
• Cyanobacteria and myxobacteria are examples of multicellular bacteria
• Cyanobacteria cells adhere to each other through a common cell wall, forming long
multicellular filaments; energy through photosynthesis
• Average nucleotides of bacteria is 0.6-8x106
• Minimum requirement: 150 genes
Typical Structure of Bacterial Cell Wall
• Structures: external to cell wall, cell wall, and internal to cell wall
• Fimbriae and pili are similar but have different functions
find more resources at oneclass.com
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• Periplasm is the space between cell wall and cell membrane
• Acts as a buffer between the inside area and the outside environment
• Gram-negative cells excrete enzymes in the periplasmic space
• Plasmid is a small DNA molecule within a cell that is physically separated from the chromosomal
DNA and can replicate independently
• Resistance to antibiotics
• Inclusion bodies are used for the storage of phosphate, carbon, nitrogen and sulfur
• Nucleoid is the area where the DNA is present
The Cytoplasm
• 80% water 20% proteins
• Largest area is the nucleoid region
• Remainder of cytoplasm is a solution of macromolecules (tRNA, mRNA, rRNA, proteins etc.)
• Inclusion bodies (elementary bodies) may also be present
• Ex: Polyhydroxybutyrate granules: carbon storage
• Ex: Sulfur globules: sulfur storage
• Usually sites for viral replication
• Made up of capsid proteins
• Gas vesicles
• Hollow structure made up of proteins
• Mostly restricted to planktonic bacteria
• Provide buoyancy
• Carboxysomes
• Site of photosynthetic carbon fixation reactions
• Contains Rubisco which the rate limiting enzyme in the Calvin Cycle
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Size of bacteria varies greatly: usually smaller than eukaryal cells (bacteria are often 0. 5-5 m in length, mycoplasma gallicepticum is a parasitic bacterium which lives in the primate bladder and lack a. Small eukaryal cells are usually >5 m in diameter cell wall; smallest known organism capable of independent growth and reproduction. Largest bacteria ever discovered are thiomargarita namibiensis and are found in the ocean sediments. Morphology of bacterial cells: bacteria take on many shapes. Spherical (s. coccus, pl. cocci: rod-shaped (s. bacillus, pl. bacilli, curved rod (s. vibrio, pl. vibrios) Structures: external to cell wall, cell wall, and internal to cell wall. Dna and can replicate independently: resistance to antibiotics. Inclusion bodies are used for the storage of phosphate, carbon, nitrogen and sulfur: nucleoid is the area where the dna is present. Largest area is the nucleoid region: remainder of cytoplasm is a solution of macromolecules (trna, mrna, rrna, proteins etc. )
