Questions and Answers
What is the characteristic of the peptidoglycan layer in Gram-positive bacteria?
What is the characteristic of the small subunit rRNA in Bacteria?
What is the main difference between Archaea and Eukarya in terms of cell type?
Which of the following is true about Mycoplasmas?
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What is the characteristic of the genetic material in Bacteria?
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What is the significance of Mollicutes?
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What is the characteristic of the small subunit rRNA in Eukarya?
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Which of the following is NOT a characteristic of Bacteria?
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What is the characteristic of the membrane lipids in Archaea?
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Which of the following is a biological significance of Mollicutes?
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Which of the following structures is involved in the Gram staining process?
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Which of the following is a characteristic of Gram-negative bacteria?
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What is the function of ribosomes in bacterial cells?
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Which of the following is a type of appendage found in bacterial cells?
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What is the function of the cytoskeleton in bacterial cells?
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Which of the following is a structure found in bacterial cells that is involved in the storage of genetic material?
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Study Notes
The Three Domains
- The three domains of life are based on the small subunit rRNA
- Criteria for distinguishing between the three domains include the side bulge in the hairpin loop and the number of nucleotides
- Bacteria have a 6-nucleotide bulge, Archaea have a 7-nucleotide bulge, and Eukarya have a 7-nucleotide bulge
Similarities and Differences
- Cell type: Bacteria are prokaryotic, Archaea are prokaryotic, and Eukarya are eukaryotic
- Cell wall: Bacteria have peptidoglycan (murein), Archaea have variable or no murein, and Eukarya have variable (CHOs) cell walls
- Membrane lipids: Bacteria have diacyl D-glycerol diester, Archaea have isoprenoid L-glycerol diether or L-glycerol tetraethers, and Eukarya have D-glycerol ester-linked
- Genetic material: All three domains have circular DNA, operons, and introns
- Antibiotic sensitivity: All three domains are sensitive to antibiotics
- Photosynthesis: All three domains can undergo photosynthesis
Mycoplasmas
- Mycoplasmas are formerly known as PPLOs (Pleuropneomonia-like organisms)
- They belong to Class Mollicutes and are the simplest and smallest cells
- Mycoplasmas are devoid of a cell wall and have a minimum of structures for free-living existence
- They are intermediate in size between viruses and bacteria
Prokaryotic Cell Ultrastructure
- Cell membrane
- Bacterial cell wall
- Capsule
- Pili (Fimbriae)
- Bacterial flagellum
- Nucleoid
- Plasmids
- Ribosomes
- Cytosol
- Storage granules
- Cytoskeleton
Cell Membrane
- Mesosomes
- Magnetosome
- Chromatophores
Bacterial Cell Wall
- Peptidoglycan (murein)
- Gram + versus Gram -:
- Gram + has a thick peptidoglycan cell wall with teichoic acids and lipoteichoic acids
- Gram - has a thin peptidoglycan cell wall with an outer layer composed of lipopolysaccharides, lipoproteins, and phospholipids
- Periplasmic space: absent in Gram + and present in Gram -
- Basal rings: one pair in Gram + and two pairs in Gram -
- Gram staining: violet in Gram + and red in Gram -
Eukaryotic Cell Ultrastructure
- Typical animal cell
- Typical plant cell
- Lysosomes in mammalian cells
- Peroxisomes
- Endoplasmic Reticulum
- Golgi Apparatus
- Plant vacuoles
- Nucleus
- Mitochondria
- Chloroplasts
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Description
This quiz covers the ultrastructure of cells, including the three domains of life: Bacteria, Archaea, and Eukarya. It explores the characteristics of each domain and how they differ from one another.