Podcast
Questions and Answers
Which of the following organisms are NOT classified as microbes?
Which of the following organisms are NOT classified as microbes?
- Fungi
- Viruses
- Plants (correct)
- Bacteria
All bacteria are harmful to humans.
All bacteria are harmful to humans.
False (B)
What is the main characteristic that distinguishes bacteria from other microbes?
What is the main characteristic that distinguishes bacteria from other microbes?
Bacteria are prokaryotic organisms, meaning they lack a true nucleus and other membrane-bound organelles.
Fungi are ______ organisms, meaning they obtain their nutrients from other organisms.
Fungi are ______ organisms, meaning they obtain their nutrients from other organisms.
Which of the following is a characteristic of bacteria?
Which of the following is a characteristic of bacteria?
Match the following types of microbes with their general characteristics:
Match the following types of microbes with their general characteristics:
Which of these characteristics is NOT common to both Gram-positive and Gram-negative bacteria?
Which of these characteristics is NOT common to both Gram-positive and Gram-negative bacteria?
Viruses can reproduce independently of a host cell.
Viruses can reproduce independently of a host cell.
What is the primary function of teichoic acids in Gram-positive bacteria?
What is the primary function of teichoic acids in Gram-positive bacteria?
The ______ is a space located between the inner and outer membranes of Gram-negative bacteria.
The ______ is a space located between the inner and outer membranes of Gram-negative bacteria.
Match the following components of the bacterial cell wall with their corresponding layer:
Match the following components of the bacterial cell wall with their corresponding layer:
Which of these is NOT a beneficial function of microbes?
Which of these is NOT a beneficial function of microbes?
All protozoa are parasitic.
All protozoa are parasitic.
What are virulence factors, and how do they contribute to pathogenicity?
What are virulence factors, and how do they contribute to pathogenicity?
Flashcards
Microbiology
Microbiology
The study of microscopic organisms like bacteria and viruses.
Bacteria
Bacteria
Microscopic single-celled organisms found in diverse environments.
Characteristics of Bacteria
Characteristics of Bacteria
Double-stranded DNA, small free ribosomes, no membrane-bound organelles.
Fungi
Fungi
Non-motile eukaryotes with rigid cell walls, heterotrophic, most are filamentous.
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Fungal Infections
Fungal Infections
Occur when host immune defenses are weakened; only a few species are pathogens.
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Algae
Algae
Simple plants, including microalgae and macroalgae, that perform photosynthesis.
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Microalgae
Microalgae
Tiny algae that can photosynthesize and include cyanobacteria.
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Autotrophic Growth
Autotrophic Growth
Photosynthesis process used by most microalgae to obtain nutrients.
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Characteristics of Viruses
Characteristics of Viruses
Viruses exhibit both living (reproduce, mutate) and non-living (acellular, no metabolism) traits.
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Living Characteristics of Viruses
Living Characteristics of Viruses
They reproduce only in host cells and can mutate rapidly.
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Non-Living Characteristics of Viruses
Non-Living Characteristics of Viruses
Acellular, cannot metabolize on their own, and contain either DNA or RNA.
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Protozoa
Protozoa
Single-celled microorganisms with a nucleus, may be free-living or parasitic.
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Pathogenic Microbes
Pathogenic Microbes
Microbes that can cause infections or diseases, using virulence factors to evade host defenses.
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Virulence Factors
Virulence Factors
Traits of pathogenic microbes that enhance their ability to infect and evade the immune system.
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Gram-Positive Bacteria
Gram-Positive Bacteria
Bacteria with a thick peptidoglycan cell wall and teichoic acids, retaining purple dye in staining.
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Gram-Negative Bacteria
Gram-Negative Bacteria
Bacteria with a thin peptidoglycan layer and an outer membrane, do not retain purple stain.
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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.
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