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Questions and Answers
What is the main characteristic that distinguishes Gram positive bacteria from Gram negative bacteria?
Which part of a bacterial flagellum is considered the longest portion?
Which statement about the glycocalyx is true?
What role do mesosomes play in bacterial cells?
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What is the primary function of pili in bacteria?
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Which of the following is not a primary component of the bacterial flagellum?
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What characteristic is true about the plasma membrane of bacteria?
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What structural feature distinguishes some cyanobacteria from other prokaryotes?
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What is the primary function of the rough endoplasmic reticulum?
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What role do centrioles play during cell division in animal cells?
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Which part of the mitochondria is responsible for oxidative phosphorylation?
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Which organelle is involved in packing and transporting cell secretions?
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What type of plastids are responsible for photosynthesis in plant cells?
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Who first explained that new cells are formed from pre-existing cells?
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What does the term 'eukaryotic cells' refer to?
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Which of the following structures is found only in eukaryotic cells?
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What is the role of ribosomes in both prokaryotic and eukaryotic cells?
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Which of the following is NOT a characteristic of the cell theory?
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What distinguishes prokaryotic cells from eukaryotic cells?
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Which organelle is specifically associated with animal cells and assists in cell division?
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What is the semi-fluid matrix found in both prokaryotic and eukaryotic cells called?
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What is the primary function of cilia?
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Which structural arrangement characterizes the axoneme of cilia and flagella?
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What are the basal bodies in relation to cilia and flagella?
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How do flagella differ from cilia in terms of structure?
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What type of microtubule arrangement is found in the axoneme?
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What component connects the central tubules in the axoneme?
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Which statement is true about the flagella of prokaryotic bacteria compared to eukaryotic flagella?
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What role do linkers play in the structure of cilia and flagella?
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What is the structural arrangement of centrioles within a centrosome?
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What is the composition of the peripheral fibrils of a centriole?
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What role do centrioles play during cell division in animal cells?
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What is the hub in the proximal region of a centriole primarily composed of?
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What did Robert Brown describe in 1831 that is crucial to cell function?
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Study Notes
Cell Theory
- Formulated by Schleiden and Schwann, later modified by Rudolf Virchow.
- Virchow introduced the concept that new cells arise from pre-existing cells ("Omnis cellula-e cellula").
- Current cell theory includes:
- All living organisms are composed of cells and their products.
- All cells arise from pre-existing cells.
Overview of Cell Structure
-
Onion and Cheek Cells:
- Onion cells have a distinct cell wall and membrane; human cheek cells have an outer membrane.
- Both cell types contain a nucleus housing chromosomes and DNA.
Cell Types
-
Eukaryotic Cells:
- Have membrane-bound nuclei and organelles (e.g., ER, Golgi complex, mitochondria).
-
Prokaryotic Cells:
- Lack membrane-bound nuclei and organelles; have a simpler structure.
Cytoplasm
- A semi-fluid matrix in both cell types where chemical reactions necessary for cellular activities occur.
Organelles
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Eukaryotic Organelles:
- Include various structures like mitochondria, lysosomes, and vacuoles.
- Ribosomes are present in both eukaryotic and prokaryotic cells, found in cytoplasm and organelles.
-
Centrosome:
- Contains centrioles that aid in cell division and are crucial for the formation of cilia and flagella.
Bacterial Classification
- Bacteria classified based on cell envelope differences; groups:
- Gram-positive (stains) and Gram-negative (no stain).
-
Glycocalyx:
- Varies in composition, may form a slime layer or thick capsule, aiding in structure and protection.
Plasma Membrane and Mesosome
- The plasma membrane is selectively permeable, allowing interaction with the environment.
- Mesosomes, formed by plasma membrane extensions, play roles in respiration, secretion, and DNA distribution.
Motility Structures
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Flagella:
- Present in motile bacteria, consisting of filament, hook and basal body.
- Various arrangements and numbers affect bacterial motility.
-
Cilia:
- Shorter than flagella, facilitate fluid movement or cell movement.
Centrosomes and Centrioles
- Each centrosome comprises two perpendicular centrioles, organized like a cartwheel.
- Centrioles are essential for spindle formation during cell division.
Nucleus
- First described by Robert Brown; contains chromatin and nucleolus.
- Regulates organelle activities and plays a major role in heredity.
Endoplasmic Reticulum (ER)
- Composed of rough (with ribosomes) and smooth (without ribosomes) regions.
- Functions in protein synthesis and transport of substances.
Golgi Complex and Lysosomes
-
Golgi Complex:
- Membranous organelle for packaging and transporting cell secretions.
-
Lysosomes:
- Contain digestive enzymes for macromolecule breakdown.
Mitochondria and Plastids
-
Mitochondria:
- Double-membrane organelles involved in ATP generation through oxidative phosphorylation.
-
Plastids:
- Found in plant cells, with chloroplasts vital for photosynthesis (light reactions in thylakoids, dark reactions in stroma).
Cellular Unit
- The cell is the fundamental structural and functional unit of life, containing specialized organelles that perform specific functions.
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Description
Explore the fundamentals of cell theory and the structure of cells, including the distinctions between eukaryotic and prokaryotic cells. This quiz covers the contributions of Schleiden, Schwann, and Virchow, along with detailed insights into various organelles. Test your knowledge on cell components and their functions.
