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Questions and Answers
What is the primary role of lysosomes in eukaryotic cells?
What is the primary role of lysosomes in eukaryotic cells?
Which of the following enzymes is deficient in Gaucher's disease?
Which of the following enzymes is deficient in Gaucher's disease?
Which characteristic symptom is associated with Tay-Sachs disease?
Which characteristic symptom is associated with Tay-Sachs disease?
What assists lysosomal enzymes in the degradation of biomolecules?
What assists lysosomal enzymes in the degradation of biomolecules?
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Which of the following processes do lysosomes NOT participate in?
Which of the following processes do lysosomes NOT participate in?
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What is the primary function of the central vacuole in plant cells?
What is the primary function of the central vacuole in plant cells?
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Which enzyme found in peroxisomes helps to remove hydrogen atoms, producing hydrogen peroxide?
Which enzyme found in peroxisomes helps to remove hydrogen atoms, producing hydrogen peroxide?
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What role do mitochondria and chloroplasts play in relation to peroxisomes?
What role do mitochondria and chloroplasts play in relation to peroxisomes?
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Which structure is a major component of the cytoskeleton in eukaryotic cells?
Which structure is a major component of the cytoskeleton in eukaryotic cells?
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What is not a function of chloroplasts?
What is not a function of chloroplasts?
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What is a defining feature of mitochondria compared to peroxisomes?
What is a defining feature of mitochondria compared to peroxisomes?
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Which of the following statements about endosymbiont theory is correct?
Which of the following statements about endosymbiont theory is correct?
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What is the primary function of microfilaments in the cytoskeleton?
What is the primary function of microfilaments in the cytoskeleton?
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What role do microtubules play in a eukaryotic cell?
What role do microtubules play in a eukaryotic cell?
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Which protein makes up microfilaments found in the cytoskeleton?
Which protein makes up microfilaments found in the cytoskeleton?
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What is the primary function of intermediate filaments in a cell?
What is the primary function of intermediate filaments in a cell?
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What does the fluid mosaic model describe about the cell membrane structure?
What does the fluid mosaic model describe about the cell membrane structure?
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Which statement accurately represents the movement of phospholipids in biological membranes?
Which statement accurately represents the movement of phospholipids in biological membranes?
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Which function is NOT associated with the cytoskeleton?
Which function is NOT associated with the cytoskeleton?
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What is a characteristic of eukaryotic cells regarding their internal structures?
What is a characteristic of eukaryotic cells regarding their internal structures?
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Which of the following is true about filament types in the cytoskeleton?
Which of the following is true about filament types in the cytoskeleton?
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Study Notes
Cellular Structure
- Eukaryotic cells contain various organelles, each with a specific function.
- The cell's structure is organized by the cytoskeleton, including microtubules, microfilaments, and intermediate filaments.
- Organelles are not simply suspended in the cytosol; they are anchored and moved by the cytoskeleton.
Lysosomes
- Lysosomes are membrane-bound organelles found in eukaryotic cells.
- Lysosomes contain hydrolytic enzymes to break down biomolecules like proteins, lipids, carbohydrates, and nucleic acids.
- They are crucial for waste material degradation, autophagy (recycling cellular components), and defense against pathogens.
- The low internal pH aids the hydrolytic enzymes in degrading molecules.
Vacuoles
- Vacuoles are membrane-bound sacs in plant and fungal cells, acting similarly to lysosomes.
- In plants, the central vacuole stores water and ions (K+, Cl-).
Peroxisomes
- Peroxisomes are roughly spherical organelles often with a granular or crystalline core.
- They contain enzymes like catalase, used to remove hydrogen atoms and produce hydrogen peroxide (H₂O₂).
- Peroxisomes use oxygen to break down fatty acids.
- Liver peroxisomes break down alcohol.
- Peroxisomes have a role in metabolic cooperation with other organelles such as chloroplasts and mitochondria.
Mitochondria
- Mitochondria are organelles where cellular respiration occurs.
- They have an outer and inner membrane with infoldings (cristae).
- The mitochondrial matrix contains free ribosomes.
Chloroplasts
- Chloroplasts are organelles that contain chlorophyll, enabling photosynthesis.
- Chloroplasts have thylakoid membranes where light reactions of photosynthesis take place.
- Chloroplasts are found in plants and algae.
- They possess their own genome, transcription machinery, as well as ribosomes.
Endosymbiont Theory
- Endosymbiosis proposes that mitochondria and chloroplasts originated from free-living prokaryotes that were engulfed by ancestral eukaryotic cells.
- Mitochondria and chloroplasts have their own genomes, transcription machinery, and ribosomes, supporting this theory.
- Eukaryotic cells developed from engulfing an oxygen-using non-photosynthetic prokaryote that became mitochondria, and engulfing a photosynthetic prokaryote forming chloroplasts.
Lysosomal Storage Disorders
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Lysosomal storage disorders affect ~50 genes associated with malfunctioning lysosomes.
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Tay-Sachs disease is a lysosomal storage disorder caused by an enzyme defect that digests gangliosides(lipid), resulting in brain lipid buildup and neurological dysfunction.
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Gaucher disease causes a deficiency of the enzyme glucocerebrosidase leading to glucocerebroside build-up in the spleen, liver and bone marrow, resulting in enlarged liver and spleen, fatigue, anemia, bone pain and fractures, and easy bruising and bleeding.
The Cytoskeleton
- Organelles are not free-floating within eukaryotic cells.
- Three types of cytoskeletal fibers are: microtubules, microfilaments, and intermediate filaments.
- Microtubules provide structural support, maintain cell shape, and play roles in long-distance intracellular transport, cell division (mitotic spindle), and movement of organelles and vesicles.
- Microfilaments are the smallest, providing support, cell shape maintenance, short-distance intracellular transport, and roles in cell movement and division.
- Intermediate filaments are rope-like, providing mechanical strength, maintaining cell shape, and anchoring organelles.
Membrane Structure
- Biological membranes are composed of a fluid bilayer of phospholipids with embedded amphipathic proteins.
- Phospholipids move laterally within the membrane plane; infrequent flip-flops occur.
- Hydrophilic heads face the exterior; hydrophobic tails face the interior.
- Integral membrane proteins pass through the bilayer.
- Peripheral membrane proteins are associated with the membrane's surface.
- Cholesterol influences membrane fluidity.
- Unsaturated fatty acids increase fluidity at lower temperatures by introducing kinks in the tails, preventing tight packing.
General Concepts
- Eukaryotic cells have internal membranes that compartmentalize their functions.
- The genetic instructions reside in the nucleus and are carried out by ribosomes.
- The endomembrane system regulates protein traffic.
- Mitochondria and chloroplasts change energy forms and carry out metabolic functions.
- The cytoskeleton organizes cell structures and activities.
- Extracellular components and connections between cells coordinate cellular activities.
- A cell's function results from the collective action of its parts.
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Description
Explore the fascinating world of eukaryotic cells and their organelles in this quiz. Learn about lysosomes, vacuoles, and peroxisomes, and understand the role of each in cellular function. Test your knowledge on how these components contribute to the overall health of the cell.
