Cytoplasmic Organelles Overview
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Cytoplasmic Organelles Overview

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Questions and Answers

Which type of cytoplasmic organelle is characterized by an absence of membranes?

  • Rough endoplasmic reticulum
  • Mitochondria
  • Free ribosomes (correct)
  • Golgi apparatus

    • What is the approximate thickness of the cell membrane as observed under electron microscopy?

  • 7.5 - 10 nm (correct)
  • 15 - 20 nm
  • 5 - 7 nm
  • 10 - 15 nm

    • Which feature allows the cell membrane to regulate the transport of substances?

  • Its rigidity
  • Its thickness
  • Its density
  • Its selectivity (correct)

    • Which of the following is NOT classified as a membranous organelle?

    <p>Centrioles</p> Signup and view all the answers

    Which type of microscopy allows observation of the cell membrane in detail?

    <p>Electron microscopy</p> Signup and view all the answers

    What is the purpose of the Golgi apparatus in eukaryotic cells?

    <p>Modification and packaging of proteins</p> Signup and view all the answers

    Which of the following cells is the smallest among the types mentioned?

    <p>Lymphocytes</p> Signup and view all the answers

    Which structure appears as a dense thin line at low magnification in electron microscopy?

    <p>Cell membrane</p> Signup and view all the answers

    What are the main lipid components of the cell membrane?

    <p>Phospholipid bilayer and cholesterol</p> Signup and view all the answers

    Which type of proteins extend across the lipid bilayer of the cell membrane?

    <p>Intrinsic proteins</p> Signup and view all the answers

    What percentage of the cell membrane is composed of carbohydrates?

    <p>10%</p> Signup and view all the answers

    What is the primary function of the cell coat (glycocalyx)?

    <p>Immunological specificity and protection</p> Signup and view all the answers

    Which of the following is NOT a method of transporting materials through the cell membrane?

    <p>Diffusion coefficient transport</p> Signup and view all the answers

    What characterizes phagocytosis?

    <p>Engulfing solid particles</p> Signup and view all the answers

    What role does cholesterol play in the cell membrane?

    <p>It fills gaps between fatty acid tails</p> Signup and view all the answers

    Which of the following processes involves specific receptors during endocytosis?

    <p>Receptor-mediated endocytosis</p> Signup and view all the answers

    What is the primary function of mitochondria in the cell?

    <p>ATP production</p> Signup and view all the answers

    Which feature differentiates the inner membrane of mitochondria from the outer membrane?

    <p>It has cristae to increase surface area.</p> Signup and view all the answers

    What type of DNA do mitochondria possess that allows them to replicate independently?

    <p>Circular DNA</p> Signup and view all the answers

    Which of the following is a common manifestation of mitochondrial diseases?

    <p>Muscle weakness</p> Signup and view all the answers

    What substance is high in the mitochondrial matrix, indicating its role in oxidative metabolism?

    <p>Calcium</p> Signup and view all the answers

    What is the likely consequence of abnormal mitochondrial DNA?

    <p>Impaired oxidative metabolism</p> Signup and view all the answers

    Where are respiratory chain enzymes located within the mitochondria?

    <p>Cristae</p> Signup and view all the answers

    How does mitochondrial number correlate with cellular activity?

    <p>Increased number in high metabolic activity cells</p> Signup and view all the answers

    Which condition is characterized by mitochondrial encephalomyopathy and lactic acidosis?

    <p>MELAS</p> Signup and view all the answers

    What is one of the key functions of the Golgi apparatus?

    <p>Protein packaging and storage</p> Signup and view all the answers

    Which structure in the Golgi apparatus faces the cell surface?

    <p>Trans face</p> Signup and view all the answers

    Which of the following is a characteristic finding in MERRF?

    <p>Myoclonic epilepsy</p> Signup and view all the answers

    What type of vesicle carries proteins from the rough endoplasmic reticulum to the Golgi apparatus?

    <p>Transfer vesicles</p> Signup and view all the answers

    In the case of the 32-year-old woman, which of her symptoms aligns with MELAS?

    <p>Diffused muscular weakness</p> Signup and view all the answers

    Which Golgi apparatus function involves modifying proteins by adding carbohydrate groups?

    <p>Glycosylation</p> Signup and view all the answers

    What type of granules can condensing vacuoles mature into within the Golgi apparatus?

    <p>Secretory granules</p> Signup and view all the answers

    Study Notes

    Cytoplasmic Organelles

    • Cell (Plasma) Membrane

      • Bounding membrane of each cell
      • Also known as plasma membrane, plasmalemma, or unit membrane
      • Encloses cellular contents and regulates transport of substances
      • LM: invisible
      • EM: thin line (7.5-10 nm), trilaminar structure (two electron-dense lines separated by an electron-lucent zone)

    • Mitochondria

      • Vary in number and size
      • LM: Rods, granules, or filaments
      • EM: Enclosed by two membranes, each with a trilaminar unit membrane
        • Outer membrane: Smooth, contains porin, freely permeable to molecules
        • Inner membrane: Folded into cristae (increases surface area), location of respiratory chain enzymes and ATP synthetase, impermeable to small ions
        • Matrix: Filled with oxidative enzymes and dense granules that store Ca+
      • Responsible for ATP production (powerhouse of the cell)
      • Number increases in cells with high metabolic activity
      • Contains its own DNA, ribosomes, mRNA, and tRNA, so it can divide independently

    • Golgi Body

      • Membranous organelle located between the nucleus and the periphery
      • Secretory apparatus of the cell
      • LM: Negative Golgi image (darkly stained granules and fibrils) visible in intensely basophilic cells (e.g., plasma cells) with special staining techniques
      • EM: Consists of flattened vesicles (stacks), transfer vesicles, and macrovesicles (condensing vacuoles)
        • Flattened vesicles: Elongated, parallel sacs arranged in stacks, sites of protein concentration
        • Transfer vesicles: Carry proteins from the rough ER to the Golgi
        • Macrovesicles: Large vesicles, mature into secretory vesicles or secretory granules
      • Functions: Packaging and storage of proteins, modification of proteins, formation of secretory proteins, renewing the cell membrane, and formation of lysosomes.

    Mitochondrial Myopathies

    • A group of genetic disorders affecting mitochondrial function, specifically in energy-demanding cells like muscle and nervous cells

    • Can manifest as:

      • Muscle weakness: especially in extra-ocular muscles (Mitochondrial myopathy)
      • Degenerative diseases of the central nervous system: loss of optic nerve fibers, cerebellar tissue, or brain white matter degeneration
      • Metabolic disturbances: high levels of lactic acid

    • Inherited maternally: Can manifest at any age

    • Diagnosis: muscle biopsy and analysis of mitochondrial DNA

    • MELAS: Mitochondrial encephalomyopathy, lactic acidosis, and recurring stroke-like episodes

      • Other findings: muscle weakness, tonic-clonic seizures

    • MERRF: Myoclonic epilepsy with ragged red fibers

      • Other findings: generalized seizures

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    Cytoplasmic Organelles I PDF

    Description

    Test your knowledge on cytoplasmic organelles, including the cell membrane and mitochondria. This quiz covers their structure, function, and importance in cellular metabolism. Perfect for students studying cell biology or related fields.

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