Cell Biology Quiz: Eukaryotic vs Prokaryotic Cells

Introduction to Microbiology

• Microbiology is the study of living organisms too small to be seen with the naked eye, requiring a microscope. It encompasses both living microbes and certain non-living entities.
• The terms "microbe" and "microorganism" are used interchangeably.
• Microbiology is derived from Greek words:
  • Mikros: small
  • Bios: life
  • Logos: study of

Outline of Topics

• Introduction
• Definition of Terms (e.g., bacteriology, virology, mycology, parasitology, protozoology, pathogens, nonpathogens, opportunistic pathogens, indigenous microbiota)
• Importance of Microbiology
• History of Microbiology
• Major Categories of Microbes (cellular and acellular)
• Types of Microorganisms (Bacteria, Archaea, Fungi, Protozoa, Algae, Viruses, Multicellular Animal Parasites)
• Cell Structure (Eukaryotic and Prokaryotic cell structures)
• Essentials of Metabolism (Catabolism and Anabolism)
• Factors Influencing Enzymatic Activity (Temperature, pH, substance concentration, inhibitors)
• Host-Pathogen Reaction (Pathology, Infection, Host, Disease)
• Symbiosis (Commensalism, Mutualism, Parasitism)
• Opportunistic Microorganisms

What is Microbiology?

• Microbiology is the study of microbes.
• Microbes are too small to be seen with the unaided eye.
• Microbes can be either living organisms or certain non-living entities.

Definition of Terms

• Bacteriology: study of bacteria
• Virology: study of viruses
• Mycology: study of fungi
• Parasitology: study of parasites
• Protozoology: study of protozoa
• Pathogens: disease-causing microbes
• Nonpathogens: microbes that do not cause disease
• Opportunistic pathogens: microbes that do not usually cause disease under ordinary conditions, but can cause disease under certain circumstances
• Indigenous microbiota: microbes that live on or in the human body

Importance of Microbiology

• Microbes are vital in the decomposition of dead organisms and waste products.
• Many microbes participate in elemental cycles (carbon, nitrogen, oxygen, sulfur, phosphorus).
• Some microbes aid in digestion and produce substances beneficial to their host.
• Microbes play crucial roles in various food and beverage industries.
• Microbes are used to clean up industrial waste, such as oil spills, through genetic engineering.
• The human body hosts a significant number of microbes (approximately 10 times more microbes than human cells).

History of Microbiology

• The existence of human pathogens has been observed for thousands of years (e.g., in mummies).
• Early scientists identified bacterial diseases like tuberculosis, leprosy, and syphilis, malaria.
• The first recorded epidemic is traced back to Egypt (3,180 B.C.).
• Two centuries were required to establish the relationship between microbes and infectious diseases.

Pioneers in Microbiology

• Robert Hooke: first observed cells, but not microbes, and made important contributions to cell theory.
• Anton van Leeuwenhoek: discovered bacteria and protozoa using single-lens microscopes, becoming known as the "father of microbiology".
• Louis Pasteur: discovered fermentation, pasteurization, and the role of microorganisms in disease, introducing the concepts of aerobic and anaerobic organisms. Developed aseptic technique.
• Robert Koch: Established criteria to prove a specific microorganism causes a specific disease (Koch's postulates).

Major Categories of Microbes

• Acellular Microbes: Viruses (non-living entities)
• Cellular Microbes: Bacteria, Archaea, Fungi, Protozoa, Algae, and Multicellular parasites

Types of Microorganisms (Major Groups)

• Bacteria: Relatively simple single-celled organisms. Enclosed in cell walls, primarily composed of peptidoglycan. Obtain nutrition from dead or living organisms.
• Archaea: Often found in extreme environments like hot springs and salty lakes.
• Fungi: Eukaryotic organisms that can be unicellular or multicellular. Obtain nourishment by absorbing organic material.
• Protozoa: Unicellular eukaryotic microbes; move by pseudopods, flagella, or cilia. Can be free-living or parasitic.
• Algae: Photosynthetic eukaryotes found in various environments, including fresh and salt water. Essential for oxygen production.
• Viruses: Non-cellular infectious agents. Require host cells to reproduce.
• Multicellular Animal Parasites: Not strictly microorganisms; important in disease; examples include worms or insects.

Cell Structure

• Prokaryotic Cells: Lack a true nucleus and other membrane-bound organelles. Include bacteria and archaea.
• Eukaryotic Cells: Contain a true nucleus and membrane-bound organelles. Include fungi, protozoa, algae, and humans. Detailed description and diagrams of organelles provided in notes for both prokaryotic and eukaryotic cells

Essentials of Metabolism

• Metabolism: Sum of all chemical reactions within a living organism.
• Catabolism: Breakdown of complex molecules into simpler ones, releasing energy.
• Anabolism: Synthesis of complex molecules from simpler ones, usually requiring energy.
• Enzymes: Protein catalysts that lower activation energy, speeding up reactions in organisms.

Factors Influencing Enzymatic Activity

• Temperature: High temperatures denature enzymes, reducing activity. Low temperatures slow down reactions. Optimal temperature maximizes activity.
• pH: Enzymes function best at specific pH values. Optimal pH maximizes activity.
• Substance concentration: Increasing substrate concentration increases reaction rate to saturation.
• Inhibitors: Substances that reduce enzyme activity. Competitive inhibitors compete with substrate for the active site, while noncompetitive inhibitors do not.

Host-Pathogen Reaction

• Pathology: Study of disease, including cause, development, and effects.
• Infection: Invasion and growth of pathogens in the body.
• Host: Organism that shelters and supports pathogen growth.
• Disease: Abnormal state, either partial or total, whereby a body or organism is unable to perform its normal bodily functions.
• Symbiosis: Relationship between two or more different organisms or creatures; parasitism, mutualism, and commensalism are examples.

Opportunistic Microorganisms

• Microbes that usually do not cause disease under normal conditions but can cause disease under altered circumstances.
• In some cases, one microbe may create an environment that enables another microbe to cause illness or exacerbate the symptoms.