Immune Response and Food Poisoning

Microbiology and Microorganisms

• Microbiology is the study of microorganisms and their activities, including nutrition, multiplication, pathogenicity, and control.
• Microorganisms, or microbes, are microscopic organisms that are too small to be seen with the naked eye.
• Not all microorganisms cause disease, and many are useful or essential for human life.

Lines of Defense

• The third and final line of defense is the immune response, which is stimulated by the presence of an antigen (invading microbe or pathogen).
• Examples of microorganisms that can cause food poisoning include Campylobacter jejuni, which can be found in contaminated poultry, meat, and milk.

Microorganisms and Food

• Microorganisms need food for energy and growth, and can break down food to provide themselves with nutrients, making it unfit for human consumption.
• Microorganisms have been used since ancient times to make food products such as bread, cheese, yoghurt, and wine.
• Yeast, such as Saccharomyces cerevisiae, is used to make bread by breaking down sugars and providing energy for growth.

Microbiology and Disease

• Medical microbiology is the study of disease-causing microorganisms with respect to humans.
• Disease caused by a microorganism is called an infectious disease or simply an infection.
• The more we know about microorganisms, the more the quality of human life is improved.

Phylogeny and Evolution

• Phylogeny is the study of the degree of relatedness between groups of living things.
• Phylogeny is based on the process of evolution, where hereditary information in living things changes gradually over time, resulting in structural and functional changes.
• Closely related organisms have similar features because they evolved from a common ancestor.

Classification of Microorganisms

• There are six kingdoms of microorganisms: Archaebacteria, Eubacteria, Protista, Fungi, Plantae, and Animalia.
• In 1996, scientists decided to split Monera into two groups of bacteria: Archaebacteria and Eubacteria, creating a new level of classification called a DOMAIN.
• The three domains are: Bacteria, Archaea, and Eukarya.

Characteristics of Microorganisms

• Bacteria: rod-shaped cells, such as Mycobacterium tuberculosis.
• Fungi: filamentous, such as Thamnidium, and can reproduce using spores.
• Algae: unicellular or multicellular, autotrophic, and can be found in aquatic environments.
• Viruses: small, infectious particles that can cause diseases such as cold sores.
• Protozoa: unicellular, motile, and can feed using cilia or flagella.
• Helminths: parasitic worms, such as Trichinella spiralis.

Archaebacteria

• Archaebacteria are ancient bacteria that live in extreme environments, such as hot springs and salty lakes.
• They are unicellular, have no peptidoglycan in their cell wall, and can have flagella that aid in locomotion.

Algae

• Algae are unicellular or multicellular, autotrophic, and can be found in aquatic environments.
• They have chlorophyll and other photosynthetic pigments in chromatophores.
• There are three types of algae, separated by pigment color: brown, red, and green.

Microbial Nomenclature and Classification

• Microbial nomenclature is the process of naming microorganisms.
• Taxonomy is the classification of living things.
• Identification is the process of discovering and recording the traits of organisms so they can be named and classified.
• The five kingdoms of microorganisms are based on morphology, metabolism, molecular techniques, fatty acid profiles, protein differentiation, and DNA fingerprinting.
• The Woese-Fox classification system is based on rRNA and divides microorganisms into three super kingdoms: Eubacteria, Archaeabacteria, and Eukarya.