Micro Exam 1

• Van Leeuwenhoek:

  • Father of the microscope
  • Studied spontaneous generation
  • Looked at pond water and observed the first microorganisms
• Pasteur:

  • Father of microbiology
  • Used broth of ground up dead plants and animals suspended in water
  • Used a swan-neck flask to prevent contamination from outside organisms
• Redi:

  • Disproved spontaneous generation
  • Experimented with maggots and containers, concluding that flies, not food, produced maggots
  • Meat still spoiled due to bacteria
• Tyndall:

  • Discovered endospores
  • Endospores are highly resistant outer coverings in some bacteria, making them resistant to boiling
• Benefits of microorganisms:

  • Food production
  • Antibiotics
  • Vaccines
  • Decomposition
  • Degradation of waste
  • Genetic engineering
  • Normal flora
• Harms of microorganisms:

  • Cause disease
  • Spoil food
  • Deteriorate materials
  • Warfare
• Seven major taxa:

  • Kingdom (most broad)
  • Phylum
  • Class
  • Order
  • Family
  • Genus
  • Species (most specific)
• Five kingdoms of life:

  • Monera (simple)
  • Protista
  • Fungi
  • Plantae
  • Animalia (complex)
• Prokaryote:

  • Before the nucleus
  • Small, simple, no nucleus or organelles (monera)
• Eukaryote:

  • True nucleus
  • Larger, complex, nucleus and organelles
• Unicellular vs. Multicellular:

  • Monera, protista, and yeast are unicellular
  • All other fungi, plantae, and animalia are multicellular
• Autotroph vs. Heterotroph:

  • Autotroph: "self feeder", photosynthesizes (plantae)
  • Heterotroph: "fed by others", feeds on other dead organisms (monera and protista mostly heterotrophs, fungi are heterotrophs)
• Which apply to bacteria:

  • Bacteria (monera) are prokaryotic, unicellular, mostly heterotrophs
• Strain:

  • Members of the same species that vary in only minor ways
• Sizes of a virus, bacterium, and plant or animal cell:

  • Virus: measured in nanometers, up to 1000x smaller than bacteria
  • Bacteria: measured in micrometers, 250,000 bacteria could fit on a period in a sentence
• Why viruses are not found in the kingdoms of life:

  • They do not possess specific characteristics to be considered living
• Three domains:

  • Archaebacteria, eubacteria, and eukarya
• Magnification: ability to make small objects seem larger
• Resolution: the ability to distinguish two objects from each other
• Factors that affect resolution:

  • Wavelength of light
  • Oil immersion technique
• Oil immersion technique:

  • Immersing both the objective lens and the specimen in transparent oil
  • Increases the numerical aperture of the objective lens
• Simple microscope:

  • One lens (Van Leeuwenhoek's scope)
• Compound microscope:

  • Series of lenses; ocular and objectives
• Different types of microscopes:

  • Light microscope: light illuminates the object
  • Dark-field microscope: special condenser passes light toward the object at an angle
  • Phase contrast microscope: special condenser causes heavier parts of an object to stand out
• Methods to visualize a transparent object under the microscope:

  • Special microscopes and staining techniques (simple stains and differential stains)
  • Starts with heat fixation
• Advantages and disadvantages of visualizing transparent objects under the microscope:

  • Special microscopes are expensive and require special training
  • Allows visualization of living cells
  • Staining requires killing the bacteria
• Types of staining techniques:

  • Simple stains: involves one dye
  • Differential stain: involves 2 dyes that allow differentiation between bacteria
• Difference between positive stain and negative stain:

  • Positive stain: stains the cell (e.g., methylene blue)
  • Negative stain: stains everything except the cell (e.g., magic marker)
• Simple staining involves using one dye
• Differential staining involves using two dyes
• Heat fixation adheres the cells to the slide and kills the bacteria; it provides contrast between the cells and the background
• Chemicals used in the Gram Stain:

  • Primary stain: crystal violet
  • Fixative: iodine
  • Decolorizer: alcohol
  • Counterstain: safranin
• Acid Fast Stain is necessary to stain bacteria that don't take up Gram stains well, such as leprosy and tuberculosis bacteria
• Three major shapes of bacteria:

  • Cocci (sphere)
  • Bacilli (rod)
  • Spirilla (spiral)
• Arrangement of bacterial cells:

  • Diplo (pairs)
  • Strepto (chains)
  • Staphylo (cluster)
  • Tetrad (box of 4)
• Structure and function of bacterial cell structures:

  • Plasma Membrane: outermost living boundary to every cell
  • Cell Wall: outermost nonliving boundary in certain cells, protects cell from lysis, composed of peptidoglycan
  • Capsule: slime or envelope outside of plasma membrane, helps bacteria hide from immune system and colonization factors
• Flagella: tail used for movement such as in sperm cells
• Pili: not for movement, shorter eyelash like; used for colonization factors; bacteria don't have cilia they have pili
• Endospores: not all bacteria have them; very resistant; likely found in soil and water
• DNA: bacteria have 1 chromosome while humans have 46; shape of a circle, single super coiled circle