Cell Biology: Organelles Overview
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Questions and Answers

What is a main function of the smooth endoplasmic reticulum (SER) in liver cells?

  • Protein synthesis
  • Regulation of glycoprotein production
  • Hormone secretion
  • Glycogen metabolism (correct)
  • Which organelle is primarily responsible for processing and packaging proteins and lipids?

  • Nucleus
  • Mitochondria
  • Rough endoplasmic reticulum
  • Golgi apparatus (correct)
  • What type of lysosome is characterized as a homogeneous vesicle that has not yet entered a digestive process?

  • Multi-vesicular body
  • Primary Lysosome (correct)
  • Heterophagosome
  • Secondary Lysosome
  • Which surface of the Golgi stack faces the nucleus?

    <p>Cis Face</p> Signup and view all the answers

    What is the role of the cytochrome P450 enzymes in the smooth endoplasmic reticulum?

    <p>Drug detoxification</p> Signup and view all the answers

    In which type of cells is jaundice in newborns attributed to underdeveloped smooth endoplasmic reticulum?

    <p>Liver cells</p> Signup and view all the answers

    What is formed by the fusion of a secondary lysosome with solid particles?

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

    Which of the following structures can be visualized using special stains in light microscopy due to its position in protein-secreting cells?

    <p>Negative Golgi Image</p> Signup and view all the answers

    What visible characteristic indicates the presence of granules at the apical pole of secretory cells under light microscopy?

    <p>Acidophilic staining</p> Signup and view all the answers

    What is the primary function of mitochondria in cells?

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

    Which of the following structures is NOT part of the mitochondria?

    <p>Golgi apparatus</p> Signup and view all the answers

    How do new mitochondria originate?

    <p>By growth and division of existing mitochondria</p> Signup and view all the answers

    Which of the following best describes the 'intercristae' space within mitochondria?

    <p>The narrow space between the cristae of the inner membrane</p> Signup and view all the answers

    Which function is NOT performed by mitochondria?

    <p>Protein synthesis</p> Signup and view all the answers

    What is one potential consequence of mitochondrial disease?

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

    What role does the endoplasmic reticulum play in the cell?

    <p>Transport of substances</p> Signup and view all the answers

    What is the fate of indigestible compounds processed by lysosomes?

    <p>They are extruded outside the cell by exocytosis.</p> Signup and view all the answers

    What structures are referred to as lipofuscin in long-lived cells?

    <p>Residual bodies that accumulate due to lysosomal activity.</p> Signup and view all the answers

    How are lysosomal enzymes processed after being synthesized in the RER?

    <p>They are transported to the Golgi complex for modification and packaging.</p> Signup and view all the answers

    What triggers the autolysis process in cells?

    <p>The death of cells.</p> Signup and view all the answers

    What is the primary function of peroxisomes?

    <p>Oxidation of organic substrates producing hydrogen peroxide.</p> Signup and view all the answers

    Which of the following statements about lysosomes is true?

    <p>They contain hydrolytic enzymes that digest both internal and external materials.</p> Signup and view all the answers

    In lysosomal storage disorders, what happens to specific molecules within the cells?

    <p>They accumulate due to an inactive lysosomal enzyme.</p> Signup and view all the answers

    What distinguishes primary lysosomes from secondary lysosomes?

    <p>Secondary lysosomes contain digested elements.</p> Signup and view all the answers

    Study Notes

    Endoplasmic Reticulum (ER)

    • Network of interconnected membranes that extends throughout the cytoplasm of eukaryotic cells.
    • Two types: Rough ER (RER) and Smooth ER (SER).
    • RER: studded with ribosomes, involved in protein synthesis and modification.
    • SER: lacks ribosomes, involved in lipid synthesis, detoxification, and calcium storage.

    Golgi Complex (Apparatus)

    • Processes, packages, and sorts macromolecules (proteins and lipids).
    • Composed of flattened sacs called cisternae, arranged in stacks.
    • Has two faces: cis face (convex, immature) and trans face (concave, mature).
    • Transfer vesicles from RER fuse with the cis face, and secretory vesicles bud from the trans face.

    Lysosomes

    • Membrane-bound organelles containing hydrolytic enzymes.
    • Involved in intracellular digestion of various materials.
    • Two types: primary lysosomes (undigested material) and secondary lysosomes (actively digesting).
    • Secondary lysosomes include heterophagosomes, multi-vesicular bodies, and autophagosomes.
    • Lysosomal storage disorders occur when specific lysosomal enzymes are absent or inactive, leading to accumulation of undigested material within cells.

    Peroxisomes (Microbodies)

    • Small, membrane-bound organelles containing oxidative enzymes.
    • Involved in detoxification of harmful molecules using catalase enzyme, producing hydrogen peroxide (H2O2).
    • Participate in lipid metabolism.

    Secretory Granules

    • Membrane-bound granules containing secretory proteins.
    • Formed from RER and transported through Golgi complex.
    • Stored in the apical pole of secretory cells.
    • Involved in exocytosis, releasing their contents outside the cell.

    Mitochondria (The powerhouse of the cell)

    • Membranous organelles responsible for energy production (ATP).
    • Consists of two membranes: outer smooth membrane and inner folded membrane (cristae).
    • Two spaces: outer intermembrane space and inner matrix space.
    • Contains mitochondrial DNA, RNA, ribosomes, enzymes, and dense granules rich in calcium ions.
    • Originate from existing mitochondria through growth and division (binary fission).

    Medical Application of Mitochondria

    • Mitochondrial disease: dysfunction of mitochondria, reducing energy production and damages brain, heart, liver, muscles, and kidneys.
    • Causes symptoms like muscle weakness, loss of motor control, pain, gastrointestinal disorders, poor growth, cardiac disease, and liver disease.

    Functions of the Smooth Endoplasmic Reticulum (SER)

    • Lipid synthesis, particularly in steroid-producing cells like adrenal cortex cells.
    • Glycogen metabolism: enzymes involved in regulating glycogen metabolism are associated with the SER membrane (e.g., liver cells).
    • Regulation of mineral metabolism, like HCL production in the stomach.
    • Calcium storage: in skeletal and cardiac muscle fibers to control muscle contraction.
    • Drug detoxification: due to cytochrome P450 enzymes present in SER (especially liver cells).

    Medical Application of SER

    • Underdeveloped SER in liver cells in newborns leads to jaundice.
    • Jaundice results from the accumulation of bilirubin, normally metabolized by SER enzymes in liver cells and excreted as bile.

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    Description

    This quiz covers the functions and structures of key organelles, including the Endoplasmic Reticulum, Golgi Complex, and Lysosomes. Understand the roles of Rough and Smooth ER, the processing capabilities of the Golgi Apparatus, and the digestive functions of lysosomes. Test your knowledge on these essential components of eukaryotic cells.

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