Tissue Preparation and Cell Structure
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Questions and Answers

What is the main purpose of freezing tissue rapidly in liquid nitrogen?

  • To enhance the color of the tissue for clearer observation
  • To enable the growth of new cells in the tissue
  • To preserve tissue details that may be lost in other techniques (correct)
  • To reduce the size of the tissue samples

    • Which of the following components is NOT considered an organelle?

  • Ribosome
  • Golgi apparatus
  • Cytosol (correct)
  • Mitochondria

    • What thickness do sections typically have when using the freezing technique?

  • 2 - 5 µm
  • 5 - 10 µm (correct)
  • 15 - 20 µm
  • 10 - 15 µm

    • Which structure serves as the genetic control center of a eukaryotic cell?

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

    What defines membranous organelles compared to non-membranous organelles?

    <p>Membranous organelles have a lipid membrane, while non-membranous do not.</p> Signup and view all the answers

    What substance is primarily found in the cytosol of a cell?

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

    Which of the following is an example of a non-essential inclusion in a cell?

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

    The outermost cover of the cytoplasm is referred to as which structure?

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

    What is the primary component that makes up cell membranes?

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

    What appearance is created by the arrangement of phospholipids in the cell membrane as seen under electron microscopy?

    <p>Trilaminar appearance</p> Signup and view all the answers

    Which part of the phospholipid molecule is hydrophilic?

    <p>The head</p> Signup and view all the answers

    What role does cholesterol play in cell membranes?

    <p>Provides stability</p> Signup and view all the answers

    Where are glycolipids predominantly found in the cell membrane?

    <p>Outer surface</p> Signup and view all the answers

    What layer forms the cell coat or glycocalyx?

    <p>Layer of glycoproteins and glycolipids</p> Signup and view all the answers

    What function does the cell coat have?

    <p>Protecting the cell</p> Signup and view all the answers

    Which of the following is NOT a function of the glycocalyx?

    <p>Providing structural support</p> Signup and view all the answers

    What role do mitochondria play in maintaining cellular function?

    <p>They help maintain calcium ion concentration.</p> Signup and view all the answers

    Which organ systems are most affected by mitochondrial disease?

    <p>Brain, heart, liver, muscles, and kidneys.</p> Signup and view all the answers

    What is the primary function of rough endoplasmic reticulum (rER)?

    <p>Protein metabolism.</p> Signup and view all the answers

    What structural characteristic distinguishes smooth endoplasmic reticulum (sER) from rough endoplasmic reticulum (rER)?

    <p>More tubular in shape with no ribosomes.</p> Signup and view all the answers

    Which characteristic of rough endoplasmic reticulum (rER) contributes to its basophilic nature?

    <p>The extensive presence of ribosomes on its surface.</p> Signup and view all the answers

    What is a symptom associated with mitochondrial disease?

    <p>Loss of motor control.</p> Signup and view all the answers

    What is the main difference in the appearance of rough endoplasmic reticulum (rER) under an electron microscope compared to smooth endoplasmic reticulum (sER)?

    <p>rER appears as flattened tubules covered with ribosomes.</p> Signup and view all the answers

    Which organelle is responsible for the manufacture of lysosomal enzymes?

    <p>Rough Endoplasmic Reticulum.</p> Signup and view all the answers

    What is the main reason cells in the glycocalyx repel each other?

    <p>Most molecules in the glycocalyx are negatively charged.</p> Signup and view all the answers

    Which of the following accurately describes passive transport?

    <p>Molecules move down a concentration gradient.</p> Signup and view all the answers

    During which process does the cell membrane invaginate to form an endocytic vesicle?

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

    What is the role of cristae in mitochondria?

    <p>They contain respiratory enzymes for energy production.</p> Signup and view all the answers

    How many sodium ions are pumped out of the cell by the sodium-potassium pump for every two potassium ions brought in?

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

    What is the primary function of mitochondria?

    <p>To convert organic materials into ATP.</p> Signup and view all the answers

    Which of the following statements is true regarding active transport?

    <p>It requires ATP to function.</p> Signup and view all the answers

    Where does new mitochondria originate from?

    <p>From preexisting mitochondria by binary fission.</p> Signup and view all the answers

    What primary role do lysosomes serve in the digestion process within a cell?

    <p>Release enzymes to digest extracellular material</p> Signup and view all the answers

    Which type of lysosome results from the fusion of a secondary lysosome with a solid particle?

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

    What is the fate of indigestible compounds processed by lysosomes?

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

    Lysosomal enzyme synthesis begins in which cellular structure?

    <p>Rough endoplasmic reticulum</p> Signup and view all the answers

    What is lipofuscin and in which type of cells is it commonly found?

    <p>A pigment associated with aging found in neurons and heart muscle</p> Signup and view all the answers

    What is one of the primary functions of the smooth endoplasmic reticulum (SER)?

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

    Which of the following processes is NOT associated with the function of the Golgi complex?

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

    What contributes to jaundice in newborn infants?

    <p>Underdeveloped state of SER in liver cells</p> Signup and view all the answers

    Which part of the Golgi complex is responsible for the maturation of vesicles?

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

    Which type of cell would most likely contain abundant lysosomes?

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

    What is formed by budding from the mature surface of the Golgi complex?

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

    What is the primary function of lysosomes?

    <p>Hydrolysis of biomolecules</p> Signup and view all the answers

    How can secondary lysosomes be identified under an electron microscope?

    <p>Spherical heterogeneous appearance</p> Signup and view all the answers

    Study Notes

    Tissue Preparation and Freezing Technique

    • Tissues are rapidly frozen in liquid nitrogen.
    • They are cut using a cold knife in a refrigerated cabinet (cryostat).
    • This method is quicker than paraffin technique.
    • Tissue details are preserved better.
    • Tissue sections are 5-10 µm thick.
    • Intra-operative consultations (needed in tumor surgery) benefit from rapid tissue analysis.

    The Cell

    • The cell is the structural and functional unit of all living tissues.
    • Cell size varies significantly in humans.
    • Smallest cell: sperm (5 µm)
    • Largest cell: ovum (120 µm)
    • Longest cell: nerve cell (1m)
    • Cell shape varies according to function (e.g., RBCs, WBCs, nerve cells).

    Cell Structure

    • Nucleus: the control center of a eukaryotic cell.
    • Cytoplasm: the jelly-like substance surrounding the nucleus, containing organelles.
      • Organelles: specialized structures within the cytoplasm, categorized as membranous or non-membranous.
        • Membranous organelles include:
        • Cell membrane.
        • Mitochondria.
        • Endoplasmic reticulum.
        • Golgi apparatus.
        • Lysosomes.
        • Peroxisomes.
        • Coated vesicles
        • Non-membranous organelles include:
        • Ribosomes.
        • Microtubules.
        • Filaments

    Cell Membrane

    • The cell membrane is the outermost layer of the cytoplasm.
    • It surrounds the internal organelles within the cell.

    Composition of the Cell Membrane

    • The primary components of cell membranes are: lipids, proteins, and carbohydrates.
    • Phospholipids are main constituents. Each has an enlarged phosphate head (polar/hydrophilic) and two tails (non-polar/hydrophobic).
    • Cholesterol contributes to membrane stability.
    • Glycolipids are predominantly on the outer membrane surface.

    Cell Membrane Proteins

    • Integral proteins: span the entire membrane.
    • Peripheral proteins: attach to the membrane surface.
    • Membrane proteins act as channels, receptors, and perform other tasks.

    Cell Membrane Carbohydrates

    • Carbohydrate molecules attach to proteins (glycoproteins) or lipids (glycolipids) on the cell's outer surface.
    • This carbohydrate layer forms the cell coat, known as glycocalyx.

    Cell Membrane Functions

    • Passive Transport: molecules move down their concentration gradient.
    • Active Transport: molecules move against their concentration gradient, requiring energy.
    • Bulk transport: substances transported in or out using vesicles (endocytosis or exocytosis).

    Mitochondria

    • Mitochondria are the powerhouse of the cell, responsible for energy production.
    • They have two membranes: outer (smooth) and inner (folded into cristae).
    • The inner membrane has elementary particles for energy production.
    • The interior matrix space contains mitochondrial DNA, RNA & Ca++.

    Endoplasmic Reticulum (ER)

    • The ER is a network of membranous sacs involved in protein and lipid synthesis.
    • Rough ER has ribosomes attached, involved in protein synthesis.
    • Smooth ER lacks ribosomes, involved in lipid synthesis and other functions.

    Golgi Complex

    • The Golgi complex processes, packages, and sorts macromolecules (e.g., proteins, lipids).
    • It has cisternae (flattened sacs) that mature from the cis (facing nucleus) to the trans face (facing membrane).
    • The complex modifies proteins, and forms lysosomes.

    Lysosomes

    • Lysosomes are membrane-enclosed vesicles filled with hydrolytic enzymes.
    • They function as the cell's "recycling system."
    • Primary lysosomes contain enzymes, while secondary contain digested materials.
    • Lysosomes digest or remove materials, both inside and outside the cell.

    Peroxisomes (Microbodies)

    • Small, membrane-bound organelles with oxidative enzymes.
    • They play roles in lipid metabolism and detoxification.

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    Cell Structure and Membranous Structures (PDF)

    Description

    Explore the techniques of tissue preparation like freezing and learn about the fundamental unit of life, the cell. This quiz covers the structural components of cells, their functions, and differences in cell types. Perfect for biology students focusing on histology and cell biology.

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