Microbiology Quiz on Bacteria

Microbiology

• Study of microorganisms
• Microorganisms include bacteria, viruses, and fungi
• Bacteriology is the study of bacteria
• Bacteria are single-celled microorganisms
• Bacteria are also known as germs or microbes
• Bacteria are found on the skin, in water, air, and decaying matter.
• Two types of bacteria, pathogenic and non-pathogenic

Non- Pathogenic Bacteria

• Constitutes the majority of bacteria
• Important for soil fertility through decomposition
• Saprophytes belong to this group
• Do not cause disease
• Live on dead matter

Pathogenic Bacteria

• In the minority
• Produce disease in plants and animals
• Harmful because they produce disease
• Parasites belong to this group
• Require living matter for growth
• Main groups of microorganisms: saprophytes, parasites, commensals, pathogenic microorganisms, true pathogens, and opportunistic pathogens

Pathogenic Microorganisms

• Responsible for causing diseases
• True pathogens cause disease
• Opportunistic pathogens are harmless but can cause disease under certain circumstances
• Classified into different shapes: cocci, bacilli, spirilla

Cocci

• Round-shaped bacteria that can appear singly or in groups
• Staphylococci: grow in clusters, responsible for abscesses, pustules, and boils
• Diplococci: grow in pairs, cause diseases like pneumonia
• Streptococci: grow in chains, found in blood poisoning
• Singular form is Streptococcus

Bacilli

• Short, rod-shaped bacteria
• Most common bacteria
• Cause diseases like tetanus, typhoid fever, and tuberculosis

Spirilla

• Spiral or corkscrew-shaped bacteria
• Subdivided into subgroups:
  • Treponema pallidum: causes syphilis (STD)
  • Borrelia burgdorferi: causes Lyme disease (affects skin, joints, heart, and nervous system)

Defense Mechanism Against Microorganisms

• Ability to cause disease depends on the host's defense mechanism
• Skin acts as a barrier
• The acid mantle hinders microorganisms
• The immune system is the second line of defense

Conditions Reducing Host Defense

• Breaks in the skin surface
• Excessively dry skin
• Very moist skin
• Prolonged change of skin pH from acid to alkaline
• Reduced immune system

Basic Structure of Bacteria

• Cell wall surrounds the cytoplasmic membrane
• Cytoplasm encloses the DNA but doesn't contain most organelles and a nucleus
• DNA forms a coiled structure called the nucleoid
• Flagellum is a tail-like structure that helps bacteria move

Different Forms of Bacteria

• Active form (vegetative form)
• Dormant form (spore form)
• Spores are resistant to drying, heating, and chemical disinfectants
• Not all bacteria produce spores
• Spore-forming bacteria are difficult to destroy
• Bacteria that cause skin diseases like tetanus and gangrene produce spores

Factors Affecting Bacterial Survival

• Oxygen and carbon dioxide
  • Aerobic bacteria: require oxygen to survive
  • Anaerobic bacteria: do not require oxygen to survive
  • Oxygen often destroys anaerobic bacteria
  • Small amounts of CO2 are essential for all bacteria survival
• Temperature:
  • Optimum temperature: the temperature at which bacteria grow most rapidly
  • Parasitic bacteria: have an optimum temperature of 37°C
  • Bacteria living in soil and water: grow at temperatures between 20°C and -7°C
  • Third group of bacteria: thrives between 55°C and 80°C
  • Using heat and cold below the range of a specific organism is an important method for destroying bacteria
• Moisture and desiccation:
  • Desiccation: the process of drying out
  • Moist conditions: are ideal for bacterial growth
  • Bacteria can be destroyed using desiccation
  • Spores are very resistant to desiccation

Importance of Bacteriology

• Understanding bacteria is essential for developing effective antibiotics
• Used to create vaccines to prevent diseases
• Used in food production
• Use bacteria to clean up environmental pollution
• Can be used in bioremediation to clean up oil spills and other pollutants
• Used to create biofuels
• Utilized to make biodegradable plastics.