Questions and Answers
What is the primary function of the Golgi apparatus in a cell?
What structures are the primary sites of aerobic respiration within a cell?
What is true regarding the structure of cilia and flagella?
Which type of plastid is responsible for trapping light energy for photosynthesis?
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Which type of plastid is colorless and primarily used for nutrient storage?
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How do mitochondria replicate within a cell?
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Which of the following best describes the primary role of vacuoles in protists?
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Which of the following pigments do chromoplasts primarily contain?
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What describes the function of ribosomes associated with mitochondria?
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Which of the following statements about the trans face of the Golgi apparatus is most accurate?
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Study Notes
Endomembrane System
- Comprises membranous organelles that perform coordinated functions.
- Includes endoplasmic reticulum (ER), Golgi complex, lysosomes, and vacuoles.
- Lysosomes contain hydrolytic enzymes (hydrolases) active at acidic pH for digestion of carbohydrates, proteins, lipids, and nucleic acids.
Endoplasmic Reticulum (ER)
- Forms a network of tiny tubular structures in the cytoplasm.
- Divides intracellular space into two compartments: luminal (inside ER) and extraluminal (cytoplasm).
- Types of ER:
- Rough Endoplasmic Reticulum (RER): Studded with ribosomes; site of protein synthesis.
- Ribosomes produce polyribosomes, translating mRNA into proteins.
- Vacuoles are membrane-bound spaces that store water, sap, and excretory products; can occupy up to 90% of plant cell volume.
- In plants, tonoplast allows ion and material transport into vacuole against concentration gradients.
- Contractile vacuole in Amoeba aids in excretion; food vacuoles formed by engulfing food particles in protists.
Inclusion Bodies
- Non-membranous reserves in prokaryotic cells include phosphate granules, cyanophycean granules, and glycogen granules.
- Gas vacuoles found in photosynthetic bacteria allow buoyancy.
Eukaryotic Cells
- Characterized by a well-organized membrane-bound nucleus and complex organelles.
- Fluid mosaic model defines the plasma membrane structure with lateral movement of proteins; proposed by Singer & Nicolson (1972).
Functions of Cell Membrane
- Selectively permeable, facilitating transport of molecules.
- Fluid nature aids in cell growth, intercellular junctions, secretion, endocytosis, and cell division.
Golgi Apparatus
- Composed of cis (forming) and trans (maturing) faces, responsible for protein processing and secretion.
- Contains circular DNA, RNA, and 70S ribosomes for protein synthesis.
- Functions in secretion to intracellular targets or outside the cell.
Mitochondria
- Known as the powerhouses of the cell; sites of aerobic respiration.
- Generate ATP, crucial for energy needs.
- Mitochondria reproduce by fission.
Plastids
- Found in all plant cells; can be classified based on pigment content.
- Types of plastids:
- Chloroplasts: Contain chlorophyll, essential for photosynthesis.
- Chromoplasts: Contain carotenoid pigments, imparting yellow, orange, or red colors.
- Leucoplasts: Colorless plastids for nutrient storage, including amyloplasts (starch), elaioplasts (oils), and aleuroplasts (proteins).
Cilia and Flagella
- Cilia: Small hair-like structures that facilitate movement; work like oars.
- Flagella: Longer structures responsible for cell movement; differ structurally between prokaryotes and eukaryotes.
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Description
Test your knowledge on the endomembrane system and its organelles, including lysosomes and the endoplasmic reticulum (ER). This quiz covers the functions of these membranous organelles and their roles in cellular digestion. Challenge yourself to understand how these systems coordinate within the cell.
