Cell Biology: Smooth Endoplasmic Reticulum Quiz
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Questions and Answers

What is a primary function of the Smooth Endoplasmic Reticulum?

  • DNA replication
  • Cell division
  • Lipid synthesis (correct)
  • Protein synthesis

    • Which type of protein remains embedded in the ER membrane?

  • Transmembrane proteins (correct)
  • Secretory proteins
  • Cytoplasmic proteins
  • Water-soluble proteins

    • Which process is NOT associated with the Smooth Endoplasmic Reticulum?

  • Protein folding (correct)
  • Steroid hormone secretion
  • Detoxification of drugs
  • Metabolism of carbohydrates

    • What happens to proteins after post-translational processing?

    <p>They undergo further modifications</p> Signup and view all the answers

    Which type of cells is the Smooth ER particularly well developed in, related to steroid secretion?

    <p>Adrenal cortex cells</p> Signup and view all the answers

    What is one of the mechanisms by which the Smooth ER helps maintain blood glucose levels?

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

    What can cause an increase in the proliferation of the smooth endoplasmic reticulum in liver cells?

    <p>Chemical insult</p> Signup and view all the answers

    Which enzyme is involved in the conversion of glucose-6-phosphate to glucose in the Smooth ER?

    <p>Glucose-6-phosphatase</p> Signup and view all the answers

    What is the primary function of lysosomes?

    <p>Intracellular digestion of unwanted elements</p> Signup and view all the answers

    At what pH do lysosomal enzymes exhibit optimum activity?

    <p>5.0</p> Signup and view all the answers

    Which of the following best describes the composition of lysosomes?

    <p>Single outer limiting membrane with hydrolytic enzymes</p> Signup and view all the answers

    What is the role of the Golgi apparatus in lysosome formation?

    <p>Originates primary lysosomes</p> Signup and view all the answers

    Which type of granules is associated with the transport of secretory products?

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

    What type of organelles are peroxisomes often referred to as?

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

    Which of the following substances are synthesized in the Golgi apparatus?

    <p>Proteins and glycoproteins</p> Signup and view all the answers

    What characterizes secondary lysosomes?

    <p>Contain material that is yet to be digested</p> Signup and view all the answers

    What is the primary role of the sarcoplasmic reticulum in muscle cells?

    <p>Storage and release of Ca2+</p> Signup and view all the answers

    Which of the following statements about the Golgi apparatus is correct?

    <p>It operates like the 'Post Office' of the cell.</p> Signup and view all the answers

    What distinguishes the sarcoplasmic reticulum from the smooth endoplasmic reticulum?

    <p>Only the sarcoplasmic reticulum stores ca2+.</p> Signup and view all the answers

    Which of the following functions is NOT performed by the smooth endoplasmic reticulum?

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

    What happens to proteins entering the Golgi apparatus at the cis face?

    <p>They can be modified and sorted for different destinations.</p> Signup and view all the answers

    How many cisternae typically make up the Golgi apparatus?

    <p>3-7</p> Signup and view all the answers

    Which statement about the trans face of the Golgi apparatus is true?

    <p>Vesicles containing cargo exit the Golgi from this face.</p> Signup and view all the answers

    What is NOT a characteristic function of the smooth endoplasmic reticulum?

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

    In which type of cells is the sarcoplasmic reticulum primarily found?

    <p>Smooth and skeletal muscle cells</p> Signup and view all the answers

    Which of the following best describes the function of the Golgi apparatus?

    <p>It packages proteins for transport.</p> Signup and view all the answers

    What characteristic distinguishes rough endoplasmic reticulum from smooth endoplasmic reticulum?

    <p>Presence of ribosomes</p> Signup and view all the answers

    What is one of the roles of the Golgi apparatus?

    <p>Production of primary lysosomes</p> Signup and view all the answers

    Which of the following describes the structure of the endoplasmic reticulum?

    <p>Elaborate network occupying up to 50% of membrane surface</p> Signup and view all the answers

    What is the role of ribosomes attached to the rough endoplasmic reticulum?

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

    How can the endoplasmic reticulum localize in certain cytoplasmic areas?

    <p>Through flattened discs called cisternae</p> Signup and view all the answers

    What type of cells would contain more rough endoplasmic reticulum?

    <p>Cells engaged in protein synthesis</p> Signup and view all the answers

    In what context is the nuclear envelope partially reformed?

    <p>During cell division</p> Signup and view all the answers

    What is the primary function of catalase in peroxisomes?

    <p>To remove hydrogen peroxide</p> Signup and view all the answers

    Which process is involved in the release of insulin from secretory granules?

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

    What are the potential consequences of Zellweger syndrome?

    <p>Abnormalities in multiple organs leading to early death</p> Signup and view all the answers

    What type of enzymes do peroxisomes contain for oxidation reactions?

    <p>Oxidative enzymes</p> Signup and view all the answers

    What is a by-product of the oxidation reactions occurring in peroxisomes?

    <p>Hydrogen peroxide</p> Signup and view all the answers

    What is the primary role of secretory granules in certain cells?

    <p>To concentrate and store proteins</p> Signup and view all the answers

    Where do secretory vesicles originate from?

    <p>Trans-face of the Golgi Apparatus</p> Signup and view all the answers

    Which statement is true regarding the ratio of mitochondria and the presence of peroxisomes?

    <p>There are more mitochondria than peroxisomes in cells.</p> Signup and view all the answers

    Study Notes

    Cell Structure: Endoplasmic Reticulum (Smooth and Rough), Golgi

    • The Endoplasmic Reticulum (ER) is a vast network of interconnected membranes in animal cells.
    • It can occupy up to 50% of the total membrane surface.
    • The ER extends from the nuclear envelope nearly to the plasma membrane, and is a transport network.
    • The channels and tubules in the ER sometimes expand to form flattened sacs called cisternae.
    • This structure can localise the ER to specific cytoplasmic areas.

    Two Types of ER

    • Rough ER (RER):

      • Characterized by ribosomes attached to its surface, giving it a granular appearance.
      • Primarily involved in protein synthesis.
      • The ribosomes on the rough ER synthesize proteins that will be incorporated into the membrane or secreted from the cell.
      • Processes like protein folding and modification also occur in the rough ER lumen.

    • Smooth ER (SER):

      • Lacks ribosomes, appearing smooth.
      • Involved in lipid synthesis and metabolism of carbohydrates.
      • Also plays a role in detoxification of harmful substances.
      • Involved in steroid hormone synthesis, found in high concentrations in endocrine cells and glands.
      • Stores and regulates calcium ions (Ca²⁺) in specific cells, like the sarcoplasmic reticulum in skeletal muscle cells.

    Sarcoplasmic Reticulum

    • Specialised form of smooth ER in smooth and skeletal muscle cells.
    • Responsible for storing and releasing calcium ions (Ca²⁺).
    • Crucial for excitation-contraction coupling (ECC) in muscle cells.

    Golgi Apparatus

    • This organelle is present in all eukaryotic cells.
    • It is involved in processing, sorting, and packaging proteins and lipids for transport to their specific destinations.
    • Found in all eukaryotic cells.
    • May also modify membrane carbohydrates.
    • Golgi apparatus is found in some animal cells near the nucleus, in an area called the centrosome.
    • In plant cells, there are numerous, dispersed Golgi bodies throughout the cytoplasm.

    Golgi Apparatus - Structure

    • Composed of flattened, membrane-bound sacs called cisternae, which vary from 3 to 7.
    • These cisternae are interconnected by tubules.
    • Different faces of the Golgi have different functions:
      • The cis face receives proteins and lipids from the ER and modifies them.
      • The trans face packages and sends them to their destinations (e.g., lysosomes, plasma membrane, secretion).

    Golgi Apparatus - Function

    • The main function is to process, sort, and package proteins and lipids.
    • Modifies proteins after synthesis.
    • Plays a role in the transport of molecules to other parts of the cell.
    • Participates in the formation of lysosomes, which are involved in breaking down waste materials.
    • Involved in the synthesis of polysaccharides and glycosaminoglycans (GAGs).

    Membrane-bound Vesicles and Secretory Granules

    • Lysosomes:

      • Contain hydrolytic enzymes for intracellular digestion.
      • Formed by the Golgi apparatus.
      • Fuse with other vesicles containing material to be degraded, forming secondary lysosomes for the actual digestion.

    • Peroxisomes:

      • Contain oxidative enzymes, involved in various metabolic processes, particularly involving breaking down harmful substances, including the removal of hydrogen peroxide.
      • Some have a crystalline core in their matrix.

    • Secretory Granules/Vesicles:

      • Used by cells that rapidly secrete products (usually proteins).
      • Store products within these granules and release them via exocytosis when stimulated.
      • Often found in cells that produce and release hormones, neurotransmitters.

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    Description

    Test your knowledge on the functions and characteristics of the Smooth Endoplasmic Reticulum. This quiz covers key processes, protein handling, and specific cell types related to steroid secretion. Challenge yourself to understand the vital role of the Smooth ER in cellular metabolism and homeostasis.

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