Questions and Answers
What are single-celled microorganisms that exist in diverse shapes, sizes, and environments?
Bacteria
Clinical samples can include ______, ______, and ______.
blood, urine, sputum
Which of the following are examples of environmental samples? (Select all that apply)
Food samples are used in the food industry to ensure safety and quality.
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What does Gram staining differentiate bacteria based on?
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Name a bacterium that is identified as catalase positive.
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What is the purpose of the Oxidase test?
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What bacteria is identified as a facultative anaerobe?
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Match the following bacteria with their classification based on oxygen requirement:
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What type of bacteria cannot survive in the presence of oxygen?
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What type of medium is MacConkey Agar?
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Which of the following examples are Gram-positive bacteria? (Select all that apply)
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Name a bacterium that forms nitrogen-fixing nodules on leguminous plants.
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Which type of bacteria creates a symbiotic relationship with plants to aid in nitrogen fixation?
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All strains of Escherichia coli are harmful.
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What is the most potent toxin known, produced by Clostridium botulinum?
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What is Mpox formerly known as?
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What virus causes Mpox?
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How can Mpox be transmitted to humans?
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What are common symptoms of Mpox?
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What is the laboratory confirmation method for Mpox?
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Which mosquito is primarily responsible for the transmission of Zika virus?
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Zika virus transmission can occur through blood transfusion.
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What does hepatitis refer to?
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Match the following hepatitis types with their transmission route:
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Which of the following hepatitis types causes both acute and chronic infections?
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How do viruses usually enter the body of their host?
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Which of the following viruses is classified as a DNA virus?
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Viruses cannot replicate without infecting a host cell.
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What is a virion?
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Which of the following is NOT a common viral infection?
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Which type of virus mainly infects plants?
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What is the primary cause of rabies?
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The virus that causes the flu is known as the _____ virus.
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What is one health risk associated with HIV?
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Which type of virus can be transmitted through sexual contact?
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Match the following viral infections with their symptoms:
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Which of the following are common sample types for clinical samples? (Select all that apply)
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What is a Gram Staining technique used for?
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The _____ Test differentiates bacteria based on their ability to produce the enzyme catalase.
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What characteristic does MacConkey Agar differentiate?
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What are autotrophic bacteria?
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Facultative anaerobes can only survive in the presence of oxygen.
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Match the following bacterial classifications with their examples:
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What is the function of the capsid in a virus?
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What type of samples might be used in research studies involving genetically modified organisms?
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Viruses can replicate independently outside of a host cell.
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Which bacterium is an example of an obligate anaerobe?
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Study Notes
Identification of Bacteria
- Bacteria are diverse single-celled microorganisms characterized by unique cell wall structures and metabolic processes.
- Sample collection methods include clinical specimens (blood, urine, tissue), environmental samples (soil, water), food samples, industrial samples, and research samples.
- Culture-Based Methods involve using selective and differential media to encourage the growth of specific bacterial colonies.
Examination Methods
- Macroscopic Examination: Observations of colony morphology such as size, shape, color, texture, and margins can indicate bacterial identity.
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Microscopic Examination:
- Gram Staining: Differentiates bacteria into Gram-positive (purple) and Gram-negative (pink) based on cell wall composition.
- Observations of cell morphology and presence of structures like flagella/capsules.
- Biochemical Tests: Assess metabolic capabilities, including tests for catalase, oxidase, indole production, citrate utilization, coagulase, and sugar fermentation, with specific bacteria as examples.
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Molecular Techniques:
- PCR: Amplifies bacterial DNA for identification.
- 16S rRNA Sequencing: Analyzes conserved genetic regions for bacterial classification.
- Whole Genome Sequencing (WGS): Provides extensive genetic information for accurate identification.
- Serological Methods: Use antibodies to detect bacterial antigens, including ELISA and Western Blotting.
- Anaerobic Culture Techniques: Specialized methods for bacteria requiring anaerobic conditions.
Types of Bacterial Isolation Media
- General Purpose Media: Nutrient Agar supports growth of diverse non-fastidious bacteria.
- Enriched Media: Blood Agar and Chocolate Agar support fastidious bacteria and differentiate based on hemolytic properties.
- Selective Media: MacConkey and Mannitol Salt Agar selectively grow certain bacteria and differentiate based on metabolic characteristics.
- Differential Media: EMB and XLD provide visual differentiation of lactose fermenters and specific pathogens.
- Specialized Media: TCBS for Vibrio and Lowenstein-Jensen Medium for Mycobacterium species.
Classification of Bacteria
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Based on Cell Wall Composition:
- Gram-positive (e.g., Staphylococcus aureus) versus Gram-negative (e.g., Escherichia coli).
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Morphological Classification:
- Cocci: Spherical bacteria (e.g., Micrococcus luteus, Neisseria gonorrhoeae).
- Bacilli: Rod-shaped bacteria (e.g., Escherichia coli, Haemophilus influenzae).
- Spirilla: Spiral-shaped (e.g., Spirillum minus).
- Vibrios: Curved rod-shaped (e.g., Vibrio cholerae).
- Pleomorphic: Variable shape (e.g., Mycoplasma pneumoniae).
Oxygen Requirements Classification
- Obligate Aerobes: Require oxygen (e.g., Mycobacterium tuberculosis).
- Obligate Anaerobes: Cannot survive in oxygen (e.g., Clostridium botulinum).
- Facultative Anaerobes: Can utilize both aerobic and anaerobic respiration (e.g., Escherichia coli).
- Microaerophiles: Require lower than atmospheric oxygen levels (e.g., Helicobacter pylori).
- Aerotolerant Anaerobes: Can tolerate oxygen but do not use it (e.g., Lactobacillus species).
Metabolic Characteristics
- Autotrophic Bacteria: Use inorganic substances (e.g., Nitrosomonas europaea).
- Heterotrophic Bacteria: Rely on organic compounds (e.g., Pseudomonas aeruginosa).
Ecological Roles
- Symbiotic Bacteria: Form relationships with hosts (e.g., Rhizobium leguminosarum).
- Pathogenic Bacteria: Cause diseases (e.g., Salmonella enterica).
Systematic Classification of Bacteria
- Domain: Bacteria
- Kingdom: Eubacteria
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Phylum Examples:
- Firmicutes: Bacillus subtilis (produces antibiotics).
- Proteobacteria: Includes various classes, each with significant examples (e.g., Neisseria gonorrhoeae in Betaproteobacteria).
- Actinobacteria: Mycobacterium tuberculosis (common pathogen).
- Cyanobacteria: Anabaena sp. (nitrogen fixation).
- Spirochaetes: Borrelia burgdorferi (causes Lyme disease).
Identification and Classification of Bacteria
- Bacteria are single-celled microorganisms with diverse shapes and environments.
- Basic characteristics include cell wall structure, reproduction, and genetic diversity.
Sample Collection and Preparation
- Samples collected using sterile techniques from:
- Clinical sources: blood, urine, sputum, cerebrospinal fluid, tissue biopsies, swabs.
- Environmental sources: soil, water, air, healthcare surfaces.
- Food sources: meats, dairy, fruits, processed foods.
- Industrial sources: biofilms, fermentation products, waste.
- Research sources: model organisms, genetically modified bacteria, environmental DNA.
Methods of Examination
- Culture-Based Methods: Use selective and differential media to promote growth of specific bacteria.
- Macroscopic Examination: Colony morphology provides initial identification clues based on size, shape, and color.
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Microscopic Examination:
- Gram Staining differentiates bacteria into Gram-positive (purple) or Gram-negative (pink).
- Observes cell shape, arrangement, and specific structures (e.g., flagella).
- Biochemical Tests assess metabolic capabilities (e.g., catalase test differentiates Staphylococcus from Streptococcus).
- Molecular Techniques: PCR amplifies bacterial DNA for identification.
- Serological Methods: Use antibodies to detect bacterial antigens (e.g., ELISA).
- Anaerobic Culture Techniques: Specialized methods for bacteria requiring low oxygen conditions.
Types of Bacterial Isolation Media
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General Purpose Media:
- Nutrient Agar (NA) supports various non-fastidious bacteria.
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Enriched Media:
- Blood Agar (BA) used for fastidious bacteria, identifies hemolytic properties.
- Chocolate Agar (CHOC) supports growth of respiratory bacteria.
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Selective Media:
- MacConkey Agar (MAC) selects for Gram-negative bacteria.
- Mannitol Salt Agar (MSA) differentiates staphylococci.
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Differential Media:
- Eosin Methylene Blue Agar (EMB) differentiates lactose fermenters.
- Xylose Lysine Deoxycholate Agar (XLD) used for enteric pathogens.
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Specialized Media:
- Thiosulfate-Citrate-Bile Salts-Sucrose Agar (TCBS) selects for Vibrio species.
- Lowenstein-Jensen Medium (LJ) selects for Mycobacterium species.
Classification of Bacteria
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Based on Cell Wall Composition:
- Gram-positive: e.g., Staphylococcus aureus, causes skin infections.
- Gram-negative: e.g., Escherichia coli, can cause foodborne illness.
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Based on Morphology:
- Cocci: spherical shapes (e.g., Streptococcus pyogenes).
- Bacilli: rod shapes (e.g., Escherichia coli).
- Spirilla: spiral shapes (e.g., Treponema pallidum).
- Vibrios: comma-shaped (e.g., Vibrio cholerae).
- Pleomorphic: variable shapes (e.g., Mycoplasma pneumoniae).
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Based on Oxygen Requirement:
- Obligate Aerobes: need oxygen (e.g., Mycobacterium tuberculosis).
- Obligate Anaerobes: cannot tolerate oxygen (e.g., Clostridium botulinum).
- Facultative Anaerobes: can use oxygen or ferment (e.g., Escherichia coli).
- Microaerophiles: need low oxygen levels (e.g., Helicobacter pylori).
- Aerotolerant Anaerobes: tolerate oxygen, ferment energy (e.g., Lactobacillus).
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Based on Metabolic Characteristics:
- Autotrophic: e.g., Nitrosomonas europaea, oxidizes ammonia.
- Heterotrophic: e.g., Pseudomonas aeruginosa, opportunistic pathogen.
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Based on Ecological Roles:
- Symbiotic: e.g., Rhizobium leguminosarum, aids plant nitrogen fixation.
- Pathogenic: e.g., Salmonella enterica, causes salmonellosis.
Systematic Classification of Bacteria
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Bacteria classified into hierarchical categories based on evolutionary relationships.
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Domain: Bacteria, part of the three life domains: Bacteria, Archaea, Eukarya.
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Kingdom: Eubacteria.
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Phylum Examples:
- Firmicutes (Bacilli): e.g., Bacillus subtilis.
- Proteobacteria (Gammaproteobacteria): e.g., Escherichia coli.
- Actinobacteria: e.g., Mycobacterium tuberculosis.
- Cyanobacteria: e.g., Anabaena sp.
- Spirochaetes: e.g., Borrelia burgdorferi.
Virus Overview
- Viruses are non-cellular infectious agents with genetic material (DNA or RNA) encased in a protein coating (capsid).
- Require host cells for replication, leading to illnesses like respiratory infections and STIs.
- Common viral infections include flu, COVID-19, chickenpox, and HIV/AIDS.
- Smaller than bacteria, viruses range from 20-300 nm.
- Cannot be classified as living or non-living due to characteristics of both.
- Enter the host through mucous membranes or breaks in the skin.### Classification of Viruses
- Classification based on nucleic acid presence: DNA viruses (single-stranded and double-stranded) and RNA viruses (single-stranded and double-stranded).
- Examples of DNA viruses:
- Single-stranded: Picornaviruses, Parvovirus.
- Double-stranded: Adenovirus, Herpes virus.
- Examples of RNA viruses:
- Double-stranded: Reovirus.
- Single-stranded: Poliovirus, Hepatitis A, Rabies virus, Influenza virus.
- Classification based on replication properties:
- Replication in cytoplasm: All RNA viruses except Influenza.
- Replication in nucleus and cytoplasm: Influenza virus, Poxvirus.
- Replication predominantly in nucleus: All DNA viruses except Poxvirus.
- Double-stranded DNA intermediate replication: All DNA viruses, retroviruses, some tumor-causing RNA viruses.
- Single-stranded RNA intermediate: All RNA viruses except Reovirus and tumor-causing RNA viruses.
Host Range Classification
- Animal viruses: Infect animal cells; notable examples include Influenza virus, Rabies virus, Herpes virus.
- Plant viruses: Infect plant cells; examples include Potato virus, Tobacco mosaic virus.
Transmission Modes
- Airborne transmission: Through respiratory tract; examples include Swine flu and Rhinovirus.
- Fecal-oral route: Contaminated food or water transmission; examples include Hepatitis A and Poliovirus.
- Sexual transmission: Spread through intimate contact; examples include Retrovirus and Human papillomavirus.
- Transfusion-related transmission: Through blood transfusions; examples include Hepatitis B and HIV.
- Zoonotic transmission: Spread through animal bites; examples include Rabies virus and Ebola virus.
Major Virus Types
- Influenza viruses (Orthomyxoviridae): Cause flu; strains include A (avian flu, swine flu) and B.
- Human herpesvirus (Herpesviridae): Causes oral/genital herpes, chickenpox, shingles, Epstein-Barr virus.
- Coronaviruses: Include SARS-CoV-1, SARS-CoV-2 (COVID-19), and MERS; cause respiratory infections with serious outcomes.
- Human Papillomavirus (HPV): Causes warts and some cancers; casual transmission is primarily sexual.
- Enteroviruses: Affect intestinal tract; notable for causing polio and hand, foot, and mouth disease.
- Flaviviruses: Often spread by mosquitoes; examples include Zika, West Nile, dengue, yellow fever.
- Orthopoxviruses: Cause flu-like symptoms and rashes; examples include Cowpox and Mpox.
- Hepatitis viruses: Affect the liver, with variants A-E differing in transmission and severity.
- Oncoviruses: Can lead to cancer; include HPV and Human herpes virus 8 (HHV-8).
Types of Viral Infections
- Respiratory infections: Affect respiratory tract; examples include common cold, flu, COVID-19.
- Digestive system infections: Affect stomach/intestines; examples include Norovirus, Hepatitis viruses.
- Viral hemorrhagic fevers: Affect blood clotting; examples include Ebola and Yellow fever.
- Sexually transmitted infections: Spread through sexual contact; examples include HIV, HPV.
- Exanthematous infections: Cause skin rashes; examples include Measles, Chickenpox, Mpox.
- Neurological infections: Attack nervous system; examples include Polio, Rabies.
- Congenital infections: Passed from mother to child; examples include Zika, Rubella.
Common Viral Diseases
- Common cold: Caused primarily by Rhinoviruses, with symptoms including nasal congestion and cough.
- Influenza: Respiratory infection with sudden onset, fever, muscle aches; vaccination is crucial for at-risk groups.
- COVID-19: Caused by SARS-CoV-2, spread through respiratory droplets; severe cases require hospitalization.
- Respiratory Syncytial Virus (RSV): Common in children and the elderly, causing cold-like symptoms.
- Chickenpox: Highly contagious, causing itchy skin rash; preventive vaccines are available.
- Measles: Airborne disease with symptoms including fever and rash; vaccination provides effective protection.
- HIV/AIDS: Attacks immune system; transmitted sexually or through body fluids; management through antiretroviral therapy.
- Human Papillomavirus: Causes warts and can lead to cancer; vaccination and regular check-ups can prevent complications.
- Herpes infections: Painful blisters on skin, caused by HSV-1 and HSV-2; management is important though no cure exists.
- Polio: Can cause paralysis; vaccination is essential for prevention.
- Rabies: Transmitted via animal bites, leading to fatal outcomes without prompt treatment.
- Mpox: Caused by monkeypox virus, presenting with skin rashes and flu-like symptoms.
- Zika Virus: Mosquito-borne virus, asymptomatic in many cases but can cause birth defects in pregnancies.
- Hepatitis: Involves liver inflammation caused by several viruses, differing in transmission routes and disease severity.
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Description
Explore the basic characteristics and classification of bacteria in this quiz. Learn about their unique structures, reproductive methods, and diverse environments. This module builds on concepts from BIO 101 to enhance your understanding of microbiology.
