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Questions and Answers
Which of the following correctly defines Medical Microbiology?
Which of the following correctly defines Medical Microbiology?
- The study of human anatomy and physiology.
- The study of microorganisms that cannot cause human infections.
- The study of microorganisms causing infectious diseases and the human reactions to infections. (correct)
- The study of only viral infections in humans.
Which of the following is NOT included in the scope of Medical Microbiology?
Which of the following is NOT included in the scope of Medical Microbiology?
- Immunology
- Bacteriology
- Virology
- Pharmacology (correct)
What classification distinguishes microorganisms based on their cellular structure?
What classification distinguishes microorganisms based on their cellular structure?
- Multicellular and unicellular
- Pathogenic and non-pathogenic
- Prokaryotic and eukaryotic (correct)
- Aerobic and anaerobic
What is a characteristic of prokaryotic organisms?
What is a characteristic of prokaryotic organisms?
How is the genus name written in the microbiological nomenclature?
How is the genus name written in the microbiological nomenclature?
After introducing a microorganism, how can its genus name be abbreviated?
After introducing a microorganism, how can its genus name be abbreviated?
Which group of microorganisms is characterized by being unicellular or multicellular eukaryotes?
Which group of microorganisms is characterized by being unicellular or multicellular eukaryotes?
Which of the following correctly describes the binominal system of nomenclature?
Which of the following correctly describes the binominal system of nomenclature?
What type of bacteria live on or in the body of living creatures?
What type of bacteria live on or in the body of living creatures?
Which term describes bacteria that cause disease in humans, animals, or plants?
Which term describes bacteria that cause disease in humans, animals, or plants?
What is the typical size range of bacterial cells?
What is the typical size range of bacterial cells?
Which of these shapes do bacteria NOT commonly exhibit?
Which of these shapes do bacteria NOT commonly exhibit?
Which type of bacteria live on or in the body without causing harm?
Which type of bacteria live on or in the body without causing harm?
What happens when bacterial cells divide?
What happens when bacterial cells divide?
Which component of LPS is responsible for its toxic effects?
Which component of LPS is responsible for its toxic effects?
What type of bacteria typically live on decaying organic matter?
What type of bacteria typically live on decaying organic matter?
What ability does LPS have in relation to B cells?
What ability does LPS have in relation to B cells?
Which bacteria are known for showing potential pathogenic behavior when body resistance is lowered?
Which bacteria are known for showing potential pathogenic behavior when body resistance is lowered?
What is the role of porins in the outer membrane of Gram-negative bacteria?
What is the role of porins in the outer membrane of Gram-negative bacteria?
What is one of the main functions of the bacterial cell wall?
What is one of the main functions of the bacterial cell wall?
Which structure lies on the inside of the peptidoglycan layer in Gram-negative bacteria?
Which structure lies on the inside of the peptidoglycan layer in Gram-negative bacteria?
What function do mesosomes serve in a bacterial cell?
What function do mesosomes serve in a bacterial cell?
How does the cytoplasmic membrane contribute to the bacterial cell's physiology?
How does the cytoplasmic membrane contribute to the bacterial cell's physiology?
Which of the following statements is true regarding the Gram stain response?
Which of the following statements is true regarding the Gram stain response?
Which arrangement of cocci is characterized by bacteria in clusters?
Which arrangement of cocci is characterized by bacteria in clusters?
What is the primary structural component of the cell wall in Gram-positive bacteria?
What is the primary structural component of the cell wall in Gram-positive bacteria?
Which of the following layers is present in the cell wall of Gram-negative bacteria?
Which of the following layers is present in the cell wall of Gram-negative bacteria?
What role does the teichoic acid layer serve in Gram-positive bacteria?
What role does the teichoic acid layer serve in Gram-positive bacteria?
What substance inhibits the synthesis of peptidoglycan in bacteria?
What substance inhibits the synthesis of peptidoglycan in bacteria?
Which type of bacteria typically has a cell wall composed of only one or two sheets of peptidoglycan?
Which type of bacteria typically has a cell wall composed of only one or two sheets of peptidoglycan?
What is the function of the periplasmic space in Gram-negative bacteria?
What is the function of the periplasmic space in Gram-negative bacteria?
Which type of bacteria is characterized by chains of cocci?
Which type of bacteria is characterized by chains of cocci?
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Study Notes
Introduction to Microbiology
- Medical microbiology studies microorganisms causing infections and human responses to these infections, encompassing etiology, pathogenesis, laboratory diagnosis, treatment, and immunization.
- Major fields include Bacteriology, Virology, Mycology, Immunology, and Parasitology.
- Microorganisms are classified by size (too small for naked eye), cellular structure (unicellular or multicellular), and type (eukaryotes, prokaryotes, viruses, prions).
Microbiological Nomenclature
- The binomial system is used: each species has a genus (capitalized) and species (lowercase) name, both italicized (e.g., Bacillus anthracis - B. anthracis).
- Once written in full, genus can be abbreviated (e.g., C. albicans for Candida albicans).
Bacteriology
- Bacteria can be saprophytic (living on decomposing material) or parasitic (living on/in a host).
- Parasitic bacteria are further divided into pathogenic (disease-causing) and commensal (non-harmful but can be opportunistic).
Morphological Study of Bacteria
- Initial identification of bacteria often involves examining morphological features: size, shape, arrangement, and structure.
- Average bacterial cell size ranges from 0.75 to 4 µm.
- Shape classifications:
- Cylindrical (bacilli, e.g., E. coli)
- Spherical (cocci, e.g., Staphylococci)
- Coma-shaped (vibrios, e.g., Vibrio cholera)
- Spiral (e.g., spirochaetes).
Arrangement of Bacteria
- Arrangement can indicate division patterns:
- Clusters (Staphylococci)
- Pairs (Diplococci, e.g., Pneumococci)
- Chains (Streptococci)
- Parallel or angled bacilli (Corynebacterium diphtheriae).
Bacterial Structure
- Essential components: cell wall, cytoplasmic membrane, cytoplasm, nucleoid.
Cell Wall
- Gram-Positive Bacteria:
- Composed mainly of a thick peptidoglycan layer (50% of the wall).
- Contains teichoic acids which are critical for virulence and immune response.
- Gram-Negative Bacteria:
- Thin peptidoglycan layer (5-10%) and a protective outer membrane of lipopolysaccharides (LPS).
- LPS includes lipid A (toxic effects) and is involved in immune activation.
- Periplasmic space contains enzymes that can degrade antibiotics.
Functions of the Cell Wall
- Maintains bacterial shape and provides structural support.
- Offers protection from osmotic pressure and aids in Gram staining.
- Involved in cell division processes.
Cytoplasmic Membrane
- A semipermeable structure surrounding the cytoplasm, composed of a phospholipid bilayer with embedded proteins.
- Functions include active transport, energy generation, synthesis of cell wall precursors, secretion of enzymes/toxins, and role in DNA replication.
Mesosomes
- Invaginations of the cytoplasmic membrane which are involved in respiration and cell division, serving as the origin for the transverse septum.
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