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What is microbiology?
The study of small life forms, including viruses, bacteria, fungi, protozoa, and algae.
Which of the following sub-disciplines are part of microbiology? (Select all that apply)
What is Infection Control?
Understanding the physical and chemical properties of microorganisms to prevent contamination and infection.
Who is credited with the concept of immunization?
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What is pasteurization?
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Louis Pasteur created the first vaccines for rabies, anthrax, and cholera.
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What did John Tyndall discover about bacteria?
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Who discovered endospores?
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What role do airborne microorganisms play in infection?
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What is the primary function of granules in prokaryotic cells?
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Which structure in eukaryotic cells is involved in the synthesis of lipids and proteins?
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What role do endospores serve in bacteria?
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What is the primary function of cilia in eukaryotic cells?
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Which type of microorganism is known for causing fatal diseases and can only multiply inside a host cell?
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What type of microorganism includes organisms like mushrooms, yeast, and molds?
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Which statement about plasmids is true?
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Which characteristic distinguishes prokaryotic cells from eukaryotic cells?
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What do archaea have in common with bacteria?
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Which microorganism can exist as single-celled organisms and are known for causing intestinal infections?
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What is a characteristic feature of bacteriophages?
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Which of the following is true about prions?
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What is the optimal growth temperature for most bacteria?
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What is the primary function of mitochondria in eukaryotic cells?
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What type of bacteria are characterized by a thick cell wall and stained blue or purple?
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Which structure is responsible for packaging proteins in the cell?
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What process describes bacterial cell division?
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What is the approximate size range of bacteria?
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Which type of eukaryotic cell structure is involved in photosynthesis?
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What shapes can bacteria commonly exhibit?
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What are lysosomes primarily known for?
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What is meant by the term 'bactericidal'?
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Which of the following correctly describes the composition of viruses?
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Which stage does the viral capsid degrade to release nucleic acid in the replication process?
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What is the primary method by which viruses replicate in host cells?
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Which classifies viruses into families?
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During which viral life cycle stage does the virus bind to the host cell surface?
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What type of diseases can be caused by common bacterial pathogens?
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Which property of viruses differentiates them from bacteria?
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Which group of bacteria grows optimally at 56 degrees Celsius?
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What is the optimal pH for the growth of most bacteria that survive in the human body?
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Which type of bacteria can tolerate low oxygen concentrations but require some to grow?
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Which macromolecules are synthesized by bacteria from nutrients?
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What role does water play in bacterial growth?
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Which type of bacteria can survive in the absence of oxygen?
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What is the pH range that aciduric bacteria can survive in?
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What process do bacteria use to convert nutrients into energy and building blocks?
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Study Notes
What is microbiology?
- The study of microscopic life forms, which includes:
- Viruses
- Bacteria
- Fungi (molds and yeasts)
- Protozoa
- Algae
Microbiology Sub-Disciplines
- Bacteriology: Study of bacteria
- Mycology: Study of fungi
- Protozoology: Study of protozoa
- Virology: Study of viruses
What is Infection Control?
- Understanding the properties of microorganisms:
- Physical and chemical properties
- Locations of microorganisms
- How microorganisms grow
- How the environment and agents influence them
- Preventing contamination, infection, and spread of disease
Immunology
- Understanding the body's defense mechanisms (the immune system)
- Understanding disease prevention through immunization and natural barriers
Microbiology, Immunology, and Biochemistry
- A close relationship exists between:
- Microbiology
- Immunology
- Biochemistry
Why Study Microbiology and Infection Control?
- Microorganisms are present in a dental office
- Can lead to transmission of infectious diseases
- Infection control helps eliminate and reduce the spread of infectious diseases
Understanding Microbiology and Infection Control
- Requires understanding of morphology:
- Growth of microorganisms
- Standards of infection control
History of Microbiology
Girolamo Fracastoro
- 1546: Recognized the existence of tiny "living particles" that cause contagious diseases
- Spread of disease:
- Direct contact with humans
- Indirect contact with objects
- Famously known for naming syphilis in a poem
Antoni van Leeuwenhoek
- Discovered bacteria
- First person to see a microbe
- Developed a primitive microscope
- Named these small life forms "animacules"
- 1683: Wrote to the Royal Society about his observations on plaque between his teeth, describing it as "a little white matter, which is as thick as if 'twere batter."
Edward Jenner
- 1749-1823: Credited with the concept of immunization
- Injection of cowpox (mild disease) protected individuals from smallpox (more serious disease)
Louis Pasteur
- Known as the "Father of Immunology"
- 1850s: Associated living organisms with disease
- Saved the wine industry by heating grape juice to reduce bacterial growth.
- Process of "pasteurization" destroyed pathogens in milk and other fluids by heating to 63 degrees Celsius for 30 minutes or 72 degrees Celsius for 15 seconds.
Louis Pasteur (cont.)
- Utilized heat to destroy vegetative bacteria and resistant bacterial spores
- Discovered bacteria produced diseases such as anthrax and cholera
- Created first vaccines for rabies, anthrax, and cholera
John Tyndall
- 1820-1893:
- Discovered the need for prolonged heating to destroy bacteria
- Discovered that bacteria existed in two forms:
- Heat-sensitive
- Heat-stable
- Developed the process of "tyndallization" - intermittent heating to destroy heat-sensitive and heat-stable bacteria
Ferdinand Cohn
- 1828-1898: Discovered "endospores"
- Dormant form of bacteria with high resistance to heat, staining, and disinfection
Joseph Lister
- 1827-1912:
- Discovered the role of airborne microorganisms.
- Discovered that airborne microorganisms could be reduced with carbolic acid
- Developed the use of antiseptics in surgery to prevent infections
Major Groups of Microorganisms (MOs)
- Bacteria: Single-celled organisms varying in size, shape, and arrangement. Grow best in moist, dark environments at 98.6°F.
- Viruses: Small organisms requiring a host cell for survival and multiplication. Can cause fatal diseases.
- Algae: Organisms ranging from single-celled to multicellular (seaweed and kelp). Mostly do not cause human disease.
- Protozoa: Single-celled organisms without rigid cell walls. Found in freshwater, marine habitats, and moist soil. Some cause intestinal infections in humans, others invade blood, lungs, liver, or brain.
- Fungi: Includes mushrooms, yeast, and mold. Oral candidiasis (a fungal infection) is common in dental settings.
- Archaea: Single-celled microbes similar to bacteria in morphology, but genetically and metabolically closer to eukaryotes.
Bacteriophage & Prions
- Bacteriophage: Viruses that infect bacteria. Discovered in 1915 and 1922.
-
Prion: Infectious agent composed solely of protein. Causes rare degenerative brain disease in humans (Creutzfeldt-Jakob) and animals (Bovine Spongiform Encephalopathy).
- Prion diseases are always fatal and rapidly progressive.
Prokaryotic vs. Eukaryotic Cells
-
Prokaryotic cells: Primitive cells lacking internal membranes and a nucleus.
- Examples include bacteria.
- Capsules reduce the ability of white blood cells to engulf and destroy bacteria.
Prokaryotic Cell Structures
- Granules: Function as energy reserves.
- Ribosomes: Contain RNA and proteins, responsible for protein synthesis.
- Nucleoid: Contains DNA, embedded in the cytoplasm.
- Endospores: Thick-walled structures highly resistant to heat, drying, and chemicals. Serve as a defense mechanism against adverse conditions.
- Plasmids: Extra-chromosomal DNA. Provide bacteria with resistance to physical, chemical agents, and antibiotics.
Eukaryotic Cells
- Cell wall: Maintains cell rigidity.
- Flagella: Provide mobility, composed of hollow filaments called microtubules.
- Cilia: Enable movement and faster mobility than flagella.
-
Plasma (Cytoplasmic) Membrane: Regulates molecule movement across the membrane via active and passive transport. Endocytosis and exocytosis also occur here.
- Endocytosis: Taking in matter.
- Exocytosis: Releasing content to the exterior.
- Endoplasmic Reticulum (ER): Fluid-filled channels synthesizing lipids (smooth ER) and proteins (rough ER).
- Granules: Store polysaccharides (starch) and lipids.
- Vacuoles: Gather food.
- Vesicles: Surround proteins involved in endocytosis and exocytosis.
- Ribosomes: Larger than prokaryotic ribosomes, produce protein.
- Mitochondria: Powerhouse of the cell.
- Chloroplasts: Function in photosynthesis.
- Golgi Complex: Packages proteins, especially those for secretion.
- Lysosomes: Membranous sacs containing digestive enzymes.
- Nucleus: Contains genetic DNA material.
Characteristics of Bacterial Cells
- Size: Smallest unicellular organisms (~1-1.5 micrometers wide and 2-6 micrometers long).
- Metabolic Rate: Rapid due to high surface area to volume ratio.
-
Gram Staining: Differentiates bacteria based on cell wall thickness:
- Gram-positive: Thick cell wall, stain blue/purple.
- Gram-negative: Thin cell wall, stain pink/red.
Cell Morphology (Size and Shape)
- Cocci (singular coccus): Spherical shape.
- Bacilli (singular bacillus): Rod-shaped.
- Spirilla or spirochetes (singular spirillum): Spiral shape.
Bacterial Growth (Multiplication)
- Binary Fission: Cell division process where each cell divides into two daughter cells.
Growth Requirements of Bacteria
-
Temperature:
- Thermophiles: Optimal growth at 56°C, range 45-70°C.
- Mesophiles: Optimal growth at 37°C (body temperature), range 22-45°C.
- Psychrophiles: Optimal growth at 7°C (refrigerator temperature), range 1-22°C.
-
Acidity (pH): Most bacteria grow best at a pH of 7.0, range 5.5-8.5.
- Acidogenic: Produce acids during growth.
- Aciduric: Survive and grow in acidic environments (pH below 5.5).
- Nutrients: Bacteria need to synthesize protein, polysaccharides, lipids, and nucleic acids (DNA and RNA). They acquire building blocks like amino acids, monosaccharides, and fatty acids from the environment.
-
Oxygen Metabolism:
- Obligate aerobes: Require oxygen at 20% concentration.
- Microaerophiles: Tolerate low (4%) oxygen concentration.
- Obligate anaerobes: Cannot tolerate oxygen.
- Facultative anaerobes: Can grow with or without oxygen.
- Water: Essential for dissolving nutrients and allowing transport into cells.
Controlling Microorganisms
- High Temperatures: Kill microorganisms.
- Strong Chemicals: Used on inanimate objects, not on the body.
- Bactericidal, Virucidal, or Fungicidal: Agents or conditions that kill microorganisms, rather than simply preventing their growth.
Common Bacterial Diseases
- Tuberculosis:
- Syphilis:
- Anthrax:
- Leprosy:
- Pneumonia:
- Dental Caries/Periodontal Disease:
- Strep Throat:
- E-Coli:
- Colitis:
- Meningitis:
Periodontal Disease
- Gingivitis/ Periodontitis:
Viruses
- Size: Extremely small, about one-tenth the size of bacteria.
- Structure: Composed of a nucleic acid core (DNA or RNA) surrounded by a protein coat called a capsid. Some viruses also have an envelope made of lipids, proteins, and polysaccharides.
- Obligate Intracellular Parasites: Viruses require a host cell for growth and replication.
Viral Replication
- Attachment/Adsorption: Virus binds to host cell surface.
- Penetration: Virus enters the host cell.
- Uncoating: Capsid degrades, releasing nucleic acid.
- Replication/Synthesis: Virus uses host mechanisms to replicate its nucleic acid and capsid.
- Assembly: Capsid surrounds nucleic acid.
- Release from Host Cell: New viruses leave the host cell to infect other cells.
Classification of Viruses
- Nucleic Acid: DNA or RNA.
- Symmetry: Helical, polyhedral, spherical, complex.
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Description
This quiz explores the fundamental concepts of microbiology, including the study of microorganisms such as bacteria, viruses, fungi, and protozoa. It also covers infection control measures and the body's immune response, highlighting the interconnections between microbiology, immunology, and biochemistry. Test your knowledge on these essential topics in life sciences.
