BIOL 2 Lab #1

• Prokaryotic Cell


  • Contains a single circular chromosome, ribosomes (70S), and a cell wall made up of peptidoglycan
  • No membrane-bound organelles
• Prokaryote appearance in the fossil record


  3.5 billion years ago
• Prokaryotes were the sole inhabitants until about 2.1 billion years ago
• Habitats where Prokaryotes are present


  • Soil
  • Water
  • Acidic hot springs
  • Radioactive waste
  • Deep in the Earth's crust
  • Organic matter
  • Live bodies of plants and animals
  • Cold and dark in a lake buried a half-mile deep under the ice in Antarctica
  • Upper atmosphere
• Prokaryotic Morphology

  • Most prokaryotes are unicellular but have a variety of shapes: Cocci (Round or Spherical), Bacilli (Rod-shaped), Helical (Spiral-shaped), Filamentous (Cells that continue to elongate instead of dividing)
• Cell-Surface Structure of Prokaryotes

  • Key feature of nearly all prokaryotes is the cell wall containing peptidoglycan
  • Gram staining technique separates bacterial species into Gram-positive (Violet in Color) and Gram-negative (Red in Color) based on differences in cell wall composition
• Gram Staining

  1. Application of crystal violet

  2. Application of iodine

  3. Alcohol wash

  4. Application of safranin
• Bacterial Colonies


  • Grows from a single bacterium and is composed of millions of cells
  • Each colony has characteristic size, shape, consistency, texture, and color, useful in preliminary species identification
• Spectrum of Microbial Activity

  • Narrow Spectrum (works on either gram-negative or gram-positive bacteria, e.g., Penicillin)
  • Broad Spectrum (works on both gram-negative and gram-positive bacteria, e.g., Tetracycline)
• Bacteria Pigments

  • Some bacteria can be identified by their colorful pigments used for photosynthesis and protection from Ultraviolet light
• Microbial luminescence


  1. Found in deep sea environments and in soils

  2. Organisms have an enzyme called luciferase that releases light during cellular respiration
• Uses of luminescent bacteria in industry


  • Detect the progression of plant infections
  • Detect antibiotics in milk
  • Detect toxic pollutants
  • Detect bacteria in food
• Kingdom Monera


  Contained all the prokaryotes
• Kingdom Monera was polyphyletic and based only on cellular structure, not on any molecular evidence
• Carl Woese suggested that some prokaryotes are more closely related to eukaryotes based on molecular biology
• Domain Archaea includes extremophiles found in extreme conditions, including halophiles, thermophiles, and methanogens
• Domain Bacteria major groups


  • Proteobacteria
  • Chlamydia
  • Spirochetes
  • Cyanobacteria
  • Gram-positive Bacteria
• Scientists use PCR to analyze bacterial genes for developing phylogenetic trees showing relatedness of different organisms
• Prokaryotes can do horizontal gene transfers that make up an average of 75% of a bacteria's genome
• Group Proteobacteria is the most diverse group of bacteria, broken down into subgroups based on nutritional modes and energy sources
• Groups of organisms based on major nutritional modes and energy sources


  • Photoautotrophic (use light and CO2)
  • Photoheterotrophic (use light and organic molecules)
  • Chemoautotrophic (use inorganic molecules and CO2)
  • Chemoheterotrophic (use organic molecules for both)
• Escherichia coli (E. coli)


  • Rod-shaped, gram-negative, facultative anaerobe
  • Prolific microorganism in the human intestinal tract
  • Normally harmless but certain strains are pathogenic
  • Some strains have specialized fimbrae to bind to the intestinal wall
  • Produce toxins causing diarrhea and, in some cases, death
  • Outbreaks linked to raw milk or undercooked hamburger
• Chlamydia


  • Cocci bacteria
  • Obligate intracellular parasites of animals
  • Obtain all their ATP from host cells
  • Transmitted to humans by interpersonal contact or airborne respiratory routes
  • Gram stain results in gram-negative due to unusual cell wall lacking peptidoglycan
  • Chlamydia trachomatis is the most common cause of blindness and sexually transmitted infection
• Spirochetes


  • Helical chemoheterotrophs
  • Slender, long, helical shape
  • Contain fibrils for motility
  • Found in aquatic environments and animal bodies
  • Some may cause disease
  • Example: Treponema pallidum, causes syphilis
• Treponema pallidum is frail and cannot survive drying or chilling
• Syphilis transmission occurs through sexual intercourse, kissing, or intimate body contact
• Stages of Syphilis

  • Primary stage: Painless sore called chancre
  • Secondary stage: Rash
  • Latent stage: No external symptoms
  • Tertiary stage: Permanent damage to vital organs and death
• Cyanobacteria


  • Aerobic, photoautotrophic bacteria
  • Once called blue-green algae but are prokaryotic
  • Contain pigment phycocyanin giving them blue-green color
  • Release oxygen and fix nitrogen
  • Inhabit fresh water, marine environments, and symbiotic relationships
  • Example: Oscillatoria
• Oscillatoria is a filamentous form found in large numbers in fresh water
• Cyanobacteria can be problematic in areas with chemical pollution from synthetic detergents, causing oxygen depletion in water
• Detergents contain phosphates that allow cyanobacteria to multiply rapidly
• When cyanobacteria die, it causes decomposing bacteria to bloom, removing oxygen from the water and resulting in the death of other organisms (fish, insects, etc.)
• Example of Gram Positive Bacteria


  • Clostridium tetani, an obligate anaerobe, endospore-forming gram-positive rod
• Clostridium tetani is common in soil contaminated with animal fecal wastes
• Clostridium tetani releases a neurotoxin that blocks the relaxation pathway of muscles, causing them to contract, leading to lockjaw
• An amount of the neurotoxin weighing as much as the ink in a period of this page can kill 30 people
• Archaea are prokaryotic cells but are quite different from true bacteria, sharing some characteristics with eukaryotes
• Shared characteristics with eukaryotes include:

  1. DNA introns present
  2. RNA polymerase
  3. Start Amino Acid for protein synthesis
  4. Response to antibiotics
• Viruses are made up of genomes (DNA or RNA) enclosed in a protective coat called a capsid (protein)
• The tiniest viruses are only 20 nm in diameter (smaller than a ribosome)