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Questions and Answers
Which one of the following is NOT a characteristic of bacteria?
Which one of the following is NOT a characteristic of bacteria?
In the context of small nucleated eukaryotic unicellular organisms multiplying by budding, which of the following is the MOST likely classification?
In the context of small nucleated eukaryotic unicellular organisms multiplying by budding, which of the following is the MOST likely classification?
Based on the microscopic examination of a Gram stained smear showing Gram positive cocci arranged in grape-like clusters from a skin lesion culture, which microorganism is MOST probably isolated?
Based on the microscopic examination of a Gram stained smear showing Gram positive cocci arranged in grape-like clusters from a skin lesion culture, which microorganism is MOST probably isolated?
A bacterioscopy of sputum smear in a pneumonia case revealed the presence of diplococci with pointed ends, arranged in pairs. What kind of organism is most probably found?
A bacterioscopy of sputum smear in a pneumonia case revealed the presence of diplococci with pointed ends, arranged in pairs. What kind of organism is most probably found?
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How many stages does the Gram-staining procedure consist of?
How many stages does the Gram-staining procedure consist of?
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Which of the following is NOT a universal entity for all Eukaryotes?
Which of the following is NOT a universal entity for all Eukaryotes?
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What kind of microorganisms was found in the oropharyngeal swabs of the patient with angina?
What kind of microorganisms was found in the oropharyngeal swabs of the patient with angina?
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Which one of the statements is the MOST accurate comparison of human and bacterial cells?
Which one of the statements is the MOST accurate comparison of human and bacterial cells?
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According to Gram-staining procedure, all bacteria can be broadly divided into what basic groups?
According to Gram-staining procedure, all bacteria can be broadly divided into what basic groups?
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Which bacterial surface structure is responsible for the adherence to eukaryotic cell surface?
Which bacterial surface structure is responsible for the adherence to eukaryotic cell surface?
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Each of the following statements concerning the Gram stain is correct EXCEPT:
Each of the following statements concerning the Gram stain is correct EXCEPT:
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Obligatory structures of bacterial cell are:
Obligatory structures of bacterial cell are:
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The lysozyme hydrolyzes the linkage between N-acetylmuramic acid and N-acetyl glucosamine causing:
The lysozyme hydrolyzes the linkage between N-acetylmuramic acid and N-acetyl glucosamine causing:
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Which component of Gram-negatives LPS is responsible for toxic properties of endotoxin?
Which component of Gram-negatives LPS is responsible for toxic properties of endotoxin?
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Which of the following statements about bacterial cell wall is TRUE?
Which of the following statements about bacterial cell wall is TRUE?
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Study Notes
Characteristics of Bacteria
- Bacteria are prokaryotes, meaning they lack a nucleus and other membrane-bound organelles.
- Bacteria have a cell wall made of peptidoglycan.
- Bacteria can be classified by their shape, which can be spherical (cocci), rod-shaped (bacilli), or spiral-shaped (spirochetes).
- Bacteria can be classified by their staining properties, such as Gram-positive and Gram-negative.
Gram Stain Procedure
- The Gram stain procedure involves four steps: application of crystal violet dye, iodine treatment, decolorization with alcohol, and counterstaining with safranin.
- The Gram stain is a differential staining technique that differentiates bacteria based on the structure of their cell walls.
- Gram-positive bacteria retain the primary stain (crystal violet) and appear purple under a microscope.
- Gram-negative bacteria lose the primary stain during decolorization and are counterstained with safranin, appearing pink under a microscope.
Bacterial Structure
- The bacterial cell wall is a rigid structure that surrounds the cell membrane and provides structural support and protection.
- The peptidoglycan layer is a key component of the bacterial cell wall.
- Gram-positive bacteria have a thick peptidoglycan layer and a thin periplasmic space.
- Gram-negative bacteria have a thin peptidoglycan layer and a thick periplasmic space.
- Bacterial cell walls can be selectively targeted by antibiotics like penicillin and vancomycin.
Bacterial Surface Structures
- Some bacteria have capsules, which are glycocalyx structures that surround the cell wall and protect the bacteria from phagocytosis.
- Some bacteria have flagella, which are long, whip-like appendages that allow for movement.
- Some bacteria have pili, which are short, hair-like appendages that facilitate adherence to surfaces.
Endotoxin
- Endotoxin is a lipopolysaccharide (LPS) found in the outer membrane of Gram-negative bacteria.
- Lipid A, a component of LPS, is responsible for the toxic effects of endotoxin.
- Endotoxin can elicit strong inflammatory responses in the host.
- Endotoxin release can lead to sepsis, a life-threatening condition characterized by widespread inflammation.
Lysozyme
- Lysozyme is an enzyme found in tears, saliva, and other body fluids that degrades peptidoglycan.
Gram-Negative Bacteria
- Gram-negative bacteria have a thin layer of peptidoglycan and an outer membrane.
- The outer membrane of Gram-negative bacteria contains lipopolysaccharide (LPS).
Bacterial Cell Wall
- The bacterial cell wall is essential for bacterial survival.
- The cell wall provides structural integrity and protects the bacteria from osmotic stress.
- The cell wall can be targeted by antibiotics.
Eukaryotic Cells
- Eukaryotic cells are more complex than prokaryotic cells.
- Eukaryotic cells have a nucleus, which contains the cell's genetic material.
- Eukaryotic cells have membrane-bound organelles that perform specialized functions.
Bacterial Multiplication
- Bacteria reproduce asexually by binary fission.
- Binary fission is a process in which a single bacterial cell divides into two identical daughter cells.
- Bacterial populations can grow rapidly under favorable conditions.
Gram Staining
- The Gram stain is used to classify bacteria based on their cell wall structure.
- Gram-positive bacteria have a thick peptidoglycan layer, while Gram-negative bacteria have a thin peptidoglycan layer.
Microorganisms
- Microorganisms are microscopic organisms that include bacteria, viruses, fungi, and protozoa.
- Microorganisms can be found in a variety of environments, including soil, water, and the human body.
- Some microorganisms are beneficial, while others are harmful.
Angina
- Angina is a condition characterized by chest pain caused by reduced blood flow to the heart.
- Bacteria are not the primary cause of angina.
- However, bacteria can contribute to angina if they infect the heart.
Streptococci
- Streptococci are spherical bacteria that typically occur in chains.
- Streptococci can be found in the throat, nose, and skin.
- Some types of streptococci are responsible for diseases such as strep throat and scarlet fever.
- Streptococci are a significant human pathogen.
Staphylococcus
- Staphylococci are spherical bacteria that typically occur in clusters.
- Staphylococci are commonly found on the skin and mucous membranes.
- Some types of staphylococci are responsible for diseases such as staph infections and food poisoning.
- Staphylococci are a significant human pathogen.
Diplococci
- Diplococci are spherical bacteria that typically occur in pairs.
- Diplococci are commonly found in the respiratory tract.
- Some types of diplococci are responsible for diseases such as pneumonia.
- Diplococci are a significant human pathogen.
Budding
- Budding is a form of asexual reproduction in which a new organism develops from an outgrowth or bud due to cell division.
- Budding is common in yeast and other fungi.
Skin Lesions
- Skin lesions can be caused by a variety of microorganisms, including bacteria, fungi, and viruses.
- Bacterial infection of the skin can lead to skin lesions such as boils, abscesses, and impetigo.
- Bacterial infection can spread rapidly, so it is important to seek medical attention if you have a skin lesion.
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Description
Test your knowledge of microbiology with this quiz covering topics such as bacteria characteristics, eukaryotic organisms, and microscopic examination techniques. Questions include identifying features of bacteria, eukaryotic unicellular organisms, and interpreting microscopic examination results.
