Microbiology Classification Quiz

Microbiology Classification

• Microbiology is the study of microscopic organisms (microbes)
• Microbes include Bacteria, Viruses, Archaea, Algae, Fungi, and Protozoa

Types of Microorganisms: Bacteria

• Bacteria are microscopic single-celled organisms
• They thrive in diverse environments, including soil, oceans, and the human gut
• Humans' relationship with bacteria is complex
• Bacteria can be helpful, such as curdling milk into yogurt or aiding digestion
• Bacteria can also be destructive, causing diseases

Characteristic of Bacteria

• Bacterial DNA exists as a double-stranded loop, not within a nuclear membrane
• Bacteria have small ribosomes in the cytoplasm, lacking an endoplasmic reticulum
• They lack mitochondria and other membrane-enclosed organelles
• Bacteria have a complex peptidoglycan-protein cell wall

Fungi

• Fungi (Mycophyta) are non-motile eukaryotes with rigid cell walls and a true nucleus
• They lack photosynthetic pigments, making them heterotrophic
• Over 50,000 fungal species exist; about 300 are human pathogens
• Most fungal infections stem from weakened host immune defenses

Characteristic of Fungi

• All fungi are eukaryotic
• Most fungi are filamentous, with some being unicellular
• The protoplasm of hyphae or cells is surrounded by a rigid wall
• Fungi typically reproduce both sexually and asexually
• All fungi are achlorophyllous
• Fungi can be free-living or form relationships with other organisms

Algae

• Algae are simple plants, ranging from microscopic forms to large seaweeds like giant kelp
• Algae can reach over 100 feet in length
• Microalgae include cyanobacteria (formerly "blue-green algae"), green, brown, and red algae

General Characteristic of Algae

• Most microalgae grow through photosynthesis, converting sunlight, CO2, and nutrients (like nitrogen and phosphorus) into energy
• This growth method is called "autotrophic"

Viruses

• Viruses are infectious agents with both living and non-living characteristics
• Viruses reproduce at a high rate, but only within living host cells
• Viruses can mutate
• Viruses are acellular, meaning they lack cytoplasm and cellular organelles
• Viruses do not perform metabolism on their own
• Viruses generally contain either DNA or RNA, but never both

Protozoa

• Protozoa are microorganisms in various sizes and forms, free-living or parasitic
• They possess a nucleus containing chromosomes and organelles like mitochondria (though absent in some cases), endoplasmic reticulum, pseudopods, flagella, and cilia
• Many parasitic protozoa are transmitted by arthropods, with multiplication and transformation into infectious stages occurring within the vector

Beneficial Microbes

• Microbiome (normal flora)
• Food source
• Antibiotics and other chemicals
• Bioengineering
• Decomposers
• Ecological balance
• Biodegradation
• Bioremediation

Pathogenic Microbes

• Pathogenic microbes have abilities to cause infections or diseases in hosts
• Virulence factors aggravate host defenses, aiding infection
• Virulence factor characteristics determine pathogenicity

G+ and G- Bacterial Cell Wall

• Bacteria are classified into Gram-positive and Gram-negative based on cell wall structure and staining response
• Gram-positive cell walls have multiple layers of the plasma membrane and sometimes a capsule, with a thick peptidoglycan layer (20-80nm), composing around 90% of the dry weight. They also have teichoic acids (polysaccharides)
• Gram-negative cell walls have a thin peptidoglycan layer (7-8nm), comprising only about 10% of the dry weight, and an outer membrane with lipopolysaccharides (LPS). A lipoprotein layer connects the peptidoglycan to the outer membrane.