Microbiology Flashcards (copy)

Evolutionary Context

• Earth's Age: 4.6 billion years, with microbial cells appearing approximately 3.8-3.9 billion years ago under anoxic conditions.

• Survival: Only anaerobic microbes survived the first 2 billion years, highlighting the adaptive traits that allowed bacteria to thrive in harsh environments.

Three Domains of Life

• Domains:

  • Bacteria: Uni-cellular organisms with prokaryotic cell structure, known for their diverse metabolic capabilities.

  • Archaea: Similar to bacteria in structure but genetically distinct, often found in extreme environments (extremophiles).

  • Eukarya: Includes all organisms with complex cells, encompassing kingdoms such as Animalia, Plantae, Fungi, and Protista.

• All domains share a common ancestor indicating the evolutionary path of life on Earth.

Prokaryotic vs. Eukaryotic Cells

• Prokaryotes: Simpler cell structure, no true nucleus, typically smaller than eukaryotes, and reproduce asexually through binary fission.

• Eukaryotes: More complex cellular structure with membrane-bound organelles and a defined nucleus. Includes diverse forms of life from single-celled organisms to complex multicellular organisms.

• Differences in Key Organelles:

  • Nucleus (Eukaryotes) vs. Nucleoid (Prokaryotes)

  • Endoplasmic Reticulum, Golgi Apparatus (Eukaryotes only) playing critical roles in protein synthesis and processing.

Impact of Microorganisms on Humans

• Agents of Disease: Microorganisms can be pathogenic, leading to diseases affecting human health.

• Pathogens: Harmful microorganisms that cause infections.

• Opportunistic Pathogens: Generally harmless but can cause illness when host defenses are compromised, such as in immunocompromised patients.

Historical Perspective

• Shifting Causes of Death: Advances in sanitation and health practices have significantly reduced mortality from infectious diseases.

• Remaining Challenges: Immunocompromised patients continue to be at risk for various infectious diseases due to weakened immune systems.

• Case Studies:

  • Staphylococcus aureus: A common pathogen responsible for skin infections; approximately 20-30% of the population carries this bacterium without symptoms.

  • Candida albicans: A yeast that can cause severe infections, particularly in immunocompromised individuals, leading to significant mortality rates.

Microorganisms in Agriculture

• Nitrogen Fixation: Crucial for plant growth, Rhizobium bacteria in root nodules convert atmospheric N2 into usable NH3, highlighting the symbiotic relationships in ecosystems.

• Microorganisms are vital for the digestion in ruminants, affecting nutrient absorption and overall health.

The Human Microbiome Project

• Exploring the diverse compositions of microbiomes across individuals; the gastrointestinal tract exhibits the highest diversity, affecting health and disease predisposition.

Applications of Microbiology

• Food Industry: Fermentation processes utilize microorganisms to produce a variety of goods, including beer, yogurt, and bread, demonstrating the importance of microbiology in everyday life.

• Biotechnology: Advances in genetic engineering enable the production of important pharmaceuticals, such as insulin, showcasing the interplay between microbiology and medicine.

Conclusion and Revision Notes

• Microorganisms present a vast diversity with both harmful and beneficial roles in human health and environmental processes.

• Understanding significant differences between prokaryotic and eukaryotic organisms is fundamental in microbiology.

• Real-world applications and case studies are crucial for a comprehensive understanding of microbiological principles.