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Questions and Answers
Bacteria can range in size from about 0.125 to 10 micrometer (μm).
Bacteria can range in size from about 0.125 to 10 micrometer (μm).
True
All bacteria have a true nucleus.
All bacteria have a true nucleus.
False
Sporulation is a method of reproduction for bacteria.
Sporulation is a method of reproduction for bacteria.
False
A capsule can protect bacteria from phagocytosis.
A capsule can protect bacteria from phagocytosis.
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Bacteria require carbon, but do not need sulfur or phosphorus for nutrition.
Bacteria require carbon, but do not need sulfur or phosphorus for nutrition.
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Bacteria classified as mesophiles thrive in extremely high temperatures.
Bacteria classified as mesophiles thrive in extremely high temperatures.
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The log phase of the bacterial growth curve is characterized by a rapid increase in the number of bacteria.
The log phase of the bacterial growth curve is characterized by a rapid increase in the number of bacteria.
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Obligate anaerobes require oxygen for their growth and survival.
Obligate anaerobes require oxygen for their growth and survival.
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In the stationary phase of bacterial growth, the number of bacteria remains constant due to nutrient depletion.
In the stationary phase of bacterial growth, the number of bacteria remains constant due to nutrient depletion.
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Stains used in bacteriology can help visualize microbial cells by giving them a specific color.
Stains used in bacteriology can help visualize microbial cells by giving them a specific color.
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Study Notes
Microbiology
- Microbiology is the branch of science studying microscopic living organisms.
- Microorganisms exist everywhere on Earth and many are crucial for life processes like nutrient recycling.
- Some microorganisms are harmful but many are beneficial.
- Microbiology includes protozoa, bacteria, fungi, algae, rickettsia and viruses.
General Microbiology
- The existence of microorganisms was recognized several centuries before their discovery.
- Some early Muslim scientists theorized microorganisms caused epidemics.
- Al Razi (864-923) believed in microorganisms causing disease.
- Ibn Sina (1020) theorized tuberculosis' contagious nature and used quarantine.
Classification of Microorganisms
- Microorganisms are broadly classified into prokaryotes and eukaryotes based on their cellular structure.
- Prokaryotes lack a nucleus and membrane-bound organelles.
- Eukaryotes posses nuclei and membrane-bound organelles.
- Prokaryotes include bacteria, Rickettsia, Chlamydia, Mycoplasmas, and archaea.
- Eukaryotes include fungi, protozoa.
Bacterial Morphology
- Bacteria vary in size from 0.125 to 10 micrometers.
- Bacteria shapes include cocci (spherical), bacilli (rod-shaped), and spiral (spirilla or spirochetes).
- Bacteria can be arranged singly, in pairs, tetrads, chains, or grape-like clusters.
- Gram-staining differentiates bacteria based on cell wall composition.
Bacterial Structure
- Bacterial cells have cell walls, responsible for shape and gram staining reaction.
- Some bacterial cells have capsules which protect from phagocytosis.
- Flagella are responsible for motility
- Pili are used for adherence to surfaces.
- Genetic material (DNA) is present in the cytoplasm.
Bacterial Sporulation
- Sporulation is a highly resistant phase of some bacteria, which are resistant to heat and chemicals.
- They can survive in dormant form for many years.
Bacterial Nutrition
- Bacteria need carbon, nitrogen, sulfur, phosphorus and inorganic ions for survival
Environmental Conditions
- Bacteria are classified based on their optimal temperature ranges.
- These ranges include psychrophiles (low temps), mesophiles (moderate temps), and thermophiles (high temps).
- Bacteria are also classified by their oxygen requirements, into obligate aerobes, obligate anaerobes, facultative anaerobes, and aerotolerant organisms.
Bacterial Growth Curve
- Bacteria reproduce by binary fission, going through the stages of Lag, Log, Stationary, and Decline.
- During the log phase, bacteria reproduce rapidly.
- The stationary phase is when reproduction slows due to limited resources.
Bacterial Staining
- Staining, like Gram staining, is used to visualize and classify bacteria.
- Common stains differentiate between Gram-positive and Gram-negative organisms.
- Different stains provide different information by combining with compounds in the microbial cells.
Bacterial Cultivation
- Bacterial cultivation focuses on growing bacteria in artificial media.
- Media are classified based on their consistency (solid, semi-solid, liquid) and components (simple, enriched, selective, indicator).
Fungi
- Fungi are eukaryotic organisms with a cell wall (not made of peptidoglycans).
- They can be unicellular (yeasts) or multicellular (molds).
Viruses
- Viruses are composed of nucleic acid (DNA or RNA) surrounded by a protein coat (capsid).
- Some viruses have an envelope.
Immunity
- Immunity is the body's resistance to infection.
- Immunology studies the structure and function of the immune system.
- Antigens are foreign substances that stimulate an immune response.
- Antibodies are proteins produced by the immune system to target antigens.
- Immune responses include innate and acquired immunity.
Infection Control
- The chain of infection includes an infectious agent, reservoir, portal of exit, mode of transmission, portal of entry, and susceptible host.
- Breaking any link in the chain can prevent infection.
- Standard precautions in healthcare settings can limit infection transmission.
Nosocomial Infections
- Nosocomial infections are healthcare-acquired infections.
- These infections occur in healthcare settings and can arise from endogenous (normal flora) or exogenous sources.
- Standard protocols (PPE, hand hygiene) are crucial for prevention.
Methods of Sterilization and Disinfection
- Sterilization involves complete elimination of all forms of microbial life, including endospores.
- Disinfection is aimed at reducing microbial load to a safe level.
- Methods of sterilization/disinfection include heat (moist/dry), radiation, filtration, and chemical agents.
Examples of Diseases caused by Microorganisms
- Various diseases (e.g., urinary tract infections, meningitis, tonsillitis, pneumonia) are caused by different bacterial/fungal families.
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Description
This quiz explores key characteristics of bacteria, including their size, structure, and reproductive methods. Learn about the unique features, such as sporulation and protective capsules, that contribute to bacterial survival. Test your knowledge on bacterial nutrition requirements as well.
