Module 1 - Microorganisms and Microbiology

Introduction to Microbiology

• Microorganisms, or microbes, are organisms typically less than 1 mm in diameter, often existing as single cells or clusters.
• Contrarily, most plants and animals are multicellular organisms.

Major Groups of Microorganisms

• Viruses: Composed of nucleic acid encased in a protein coat; require living cells to reproduce; not classified as cells.
• Bacteria: Prokaryotic cells with a single chromosome; diverse group.
• Algae: Polyphyletic group; includes prokaryotic (cyanobacteria) and eukaryotic types (green and red algae); primarily found in aquatic environments; photosynthetic and produce oxygen as a by-product.
• Fungi: Eukaryotes producing spores; includes unicellular yeasts and multicellular molds made of hyphae.
• Protozoa: Unicellular eukaryotes that are typically colorless and motile, displaying a vast range of morphologies.

Historical Context

• Beijernick: Developed enrichment methods for increasing specific microbe concentrations using specialized nutrients.
• Winogradsky: Identified bacteria's roles in biogeochemical cycles, such as nitrogen fixation.

Tree of Life

• Phylogeny studies evolutionary relationships through DNA sequence analysis, illustrating evolutionary distances.
• Current phylogenetic understanding reveals three distinct cellular lineages.

Physiological Diversity of Microbes

• Microbes exhibit variations in morphology, size, physiology, and pathogenicity.
• Chemoorganotrophs: Utilize organic substances (e.g., glucose) to generate ATP; can be aerobes (requiring oxygen) or anaerobes (not requiring oxygen).
• Chemolithotrophs: Gain energy from inorganic compounds; primarily found in bacteria and archaea; don't compete with chemoorganotrophs.
• Phototrophs: Perform photosynthesis; oxygen-producing (oxygenic) photosynthesis occurs in cyanobacteria, while non-oxygen producing (anoxygenic) occurs in certain bacteria.

Microbial Diversity

• Bacterial Diversity: Includes gram-negative Proteobacteria, gram-positive bacteria (e.g., Bacillus, Streptomyces), and cyanobacteria, which were among the earliest oxygen producers.
• Archaea Diversity: Comprises seven phyla; includes diverse groups such as Crenarchaeota (hyperthermophiles) and Euryarchaeota (methanogens, extreme halophiles).

Cell Structure and Function

• Cells, the basic life unit, consist of lipid membranes/walls that compartmentalize functions, enhancing biochemical reaction efficiency.
• Microbes, except viruses, are classified as cells based on essential cellular characteristics.

Viruses

• Viruses range from 0.2 to 2 micrometers in size and are significantly smaller than bacteria; they lack cellular structures.

Protein Structures

• Proteins have various structural levels:
  • Tertiary: Final folded shape of a protein.
  • Quaternary: Arrangement of multiple polypeptides or subunits; involves independently folding units called domains.
• Denaturation of proteins leads to loss of structure and function, triggered by extreme pH, high temperature, or denaturing agents.

Upcoming Tasks

• Review chapters relevant to the module.
• Engage in blended learning activities.
• Prepare to complete Module 2 and progress to Module 3 on Microbial Nutrition.

This quiz covers the fundamentals of microorganisms and microbiology, including their definitions and historical context. Understand the significance of microbes in the ecosystem and their characteristics compared to multicellular organisms.