microbiology chp 1

Chapter 1: Introduction to Microbes and Their Building Blocks

Microbes: Tiny But Mighty

  • Microbiology: Study of living organisms that are too small to be seen without magnification.

  • Microorganisms include:

    • Bacteria

    • Algae

    • Protozoa

    • Helminths

    • Viruses: Studied here despite being non-living.

Viruses

  • Characteristics of Viruses:

    • Non-living, consist of protein-coated genetic material.

    • Parasitic: Depend on their infected host to replicate.

The Nature of Microorganisms

  • Study of Microbes:

    • Easy to reproduce and grow in large populations in the lab.

    • Difficult to observe directly; require microscopes and other indirect methods.

Microbes and the Planet

  • Evolution of Microbes:

    • Bacterial-type organisms have existed for about 3.5 billion years, became the only living inhabitants for around 2 billion years.

    • Prokaryotes: Organisms without a true nucleus.

    • Eukaryotes: First appeared about 1.8 billion years ago, possessing a true nucleus.

  • Microbial Ubiquity:

    • Found in diverse environments: Earth's crust, polar ice caps, oceans, and within plants and animals.

    • Capable of thriving in extreme conditions where other organisms cannot survive.

How Microbes Shape Our Planet: Photosynthesis

  • Types of Photosynthesis:

    • Anoxygenic Photosynthesis: No O2 produced.

    • Oxygenic Photosynthesis: O2 is produced, essential for aerobic respiration, with photosynthetic microorganisms accounting for 70% of Earth's photosynthesis.

Microbes' Environmental Role

  • Drive structure and content of soil, water, and atmosphere.

  • Produce gases like CO2, NO, and CH3 that help regulate Earth's temperature.

  • Influence mineral extraction and soil formation within the vast underground microbial community.

Human Uses of Microbes

  • Genetic Engineering: Biotechnology manipulating the genetics of organisms for products and GMOs.

  • Bioremediation: Use of microorganisms for environmental restoration and cleanup of pollutants.

Microbes Harming Humans

  • Majority of Microorganisms: Associated with humans, causing no harm.

  • Pathogens: Microbes that cause disease.

  • Infection Statistics:

    • WHO estimates 10 billion new infections annually.

    • Infectious diseases account for approximately 13 million deaths per year.

    • Notably, a child dies from malaria every 30 seconds.

Emerging and Re-emerging Infectious Diseases

  • Emerging Diseases: New diseases like AIDS, hepatitis C, and viral encephalitis significantly impacting health.

  • Re-emerging Diseases: Older diseases (e.g., tuberculosis) which are resurging due to various factors.

Microbial Causes of Non-Infectious Diseases

  • Diseases previously deemed non-infectious linked to microbial causes:

    • Gastric Ulcers: Caused by Helicobacter pylori.

    • Diabetes: Linked to Coxsackievirus.

    • Schizophrenia: Associated with borna agent.

    • Chronic infections with bacteria or viruses connected with conditions: multiple sclerosis, OCD, coronary artery disease, and obesity.

Microbes in History

  • Spontaneous Generation (Abiogenesis): The notion that life originates from invisible forces.

  • Biogenesis: The contrast belief that all life arises from previous life.

  • Historical conflict between these concepts from the 1600s to 1800s, eventually resolved by Louis Pasteur.

Pasteur’s Swan Neck Flask Experiment

  • Process of sterilizing broth and observing microbial growth.

  • Results indicated that microorganisms come from other microorganisms rather than spontaneously from the broth itself.

Role of the Microscope

  • Robert Hooke: First to describe cells using a simple magnifying glass.

  • Antoine van Leeuwenhoek: Developed small microscopes for magnification up to 300x, observing microorganisms in droplets of rainwater.

Other Important Figures in Microbiology

  • Joseph Lister: Promoted aseptic techniques in surgery.

  • Oliver Wendell Holmes and Ignaz Semmelweis: Advocated for hand washing to prevent infections.

  • Robert Koch: Verified germ theory of disease, establishing links between microbes and specific diseases.

Recent Advances in Microbiology

  • Restriction Enzymes and PCR: Key techniques in genetic manipulation and bioengineering.

  • Biofilms: Communities of bacteria and microbes that develop on surfaces; significant in various infections.

  • Small RNAs: Role in RNA silencing mechanisms affecting mRNA and gene expression.

Cellular Organization: Prokaryotes vs. Eukaryotes

  • Essential distinctions between prokaryotic cells (no nucleus) and eukaryotic cells (with a nucleus).

Five Types of Microorganisms

  • Examples include:

    • Fungus (e.g., Syncephalastrum)

    • Bacterium (e.g., E. coli)

    • Helminth (e.g., Taenia solium)

    • Protozoan (e.g., Vorticella)

    • Virus (e.g., Herpes simplex)

Macromolecules: Superstructures of Life

  • Types of Macromolecules:

    • Carbohydrates

    • Lipids

    • Proteins

    • Nucleic Acids

  • These macromolecules form the essential structures for life, previously covered in earlier studies.

Nomenclature

  • Nomenclature: The system of assigning scientific names to organisms.

  • Binomial Nomenclature: Scientific names consist of genus and species names, formatted in italics or underlined.

    • Example: Escherichia coli (abbreviated as E. coli).

Classification

  • Classification: Organizing organisms into a hierarchical structure.

  • Taxonomic Categories include:

    • Domain

    • Kingdom

    • Phylum or Division

    • Class

    • Order

    • Family

    • Genus

    • Species

Sample Taxonomy

  • Domain: Eukarya: Eukaryotic organisms, predominantly multicellular.

  • Kingdoms and Taxa Examples:

    • Kingdom: Animalia

      • Phylum: Chordata

        • Class: Mammalia

          • Order: Primates

            • Family: Hominoidea

              • Genus: Homo

                • Species: sapiens (Humans)

The Woese-Fox System

  • Taxonomic System: Based on small subunit ribosomal RNA (ssu rRNA) sequences.

  • Revealed distinct domains:

    • Bacteria

    • Archaea

    • Eukarya

Further Classification in the Woese-Fox System

  • Classification includes various groups:

    • Plants, Animals, Fungi, Protists

    • Characteristics and examples of different prokaryotes categorized under Archaea and Bacteria.

Kingdom System

  • The five-kingdom system became a standard classification from 1959 to 1969, comprising:

    • Animals

    • Plants

    • Protists

    • Monera

    • Fungi