Cytology - The Cell Overview
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Questions and Answers

What are the two main parts of a cell?

  • cell wall and nucleus
  • cell membrane and nucleus
  • cytoplasm and nucleus (correct)
  • cytoplasm and cell wall

    • What are the two main categories that cytoplasmic organelles are classified into?

  • membranous organelles and non-membranous organelles (correct)
  • structural organelles and functional organelles
  • cytoplasmic organelles and nuclear organelles
  • internal organelles and external organelles

    • The cell membrane is visible under a light microscope.

    False

    What are the three main components of a cell membrane?

    <p>lipids, proteins, and small amounts of carbohydrates</p> Signup and view all the answers

    What is the name given to the head of a phospholipid molecule?

    <p>polar end</p> Signup and view all the answers

    What is the name of the layer formed by carbohydrates on the external surface of the plasma membrane?

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

    Which of the following processes is NOT a type of endocytosis?

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

    What is the name given to the intracellular vacuole that encloses a bacterium during phagocytosis?

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

    Pinocytosis involves the ingestion of large particles such as bacteria.

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

    Which type of endocytosis involves specific membrane receptors?

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

    What is the process called where a cytoplasmic vesicle fuses with the plasma membrane to release its contents outside the cell?

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

    Mitochondria are visible under a light microscope using H&E staining.

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

    Which of the following is NOT a characteristic of the inner membrane of mitochondria?

    <p>Contains ribosomes.</p> Signup and view all the answers

    What is the function of cristae in mitochondria?

    <p>To increase the surface area for ATP production.</p> Signup and view all the answers

    The Golgi apparatus is more developed in secretory cells than in non-secretory cells.

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

    Match the following parts of the Golgi apparatus with their descriptions:

    <p>Cis face = Convex, entry side, immature face. Trans face = Concave, exit side, mature face.</p> Signup and view all the answers

    Which of the following is NOT a function of the Golgi apparatus?

    <p>Synthesis of proteins.</p> Signup and view all the answers

    What is the main function of lysosomes?

    <p>To break down unwanted material within the cell.</p> Signup and view all the answers

    Which of the following is a type of secondary lysosome?

    <p>autophagic vacuole</p> Signup and view all the answers

    The accumulation of indigestible material in lysosomes results in the formation of __.

    <p>residual bodies</p> Signup and view all the answers

    What is the name given to the yellow-brown pigment that accumulates in long-lived cells due to the accumulation of residual bodies?

    <p>lipofuscin pigment</p> Signup and view all the answers

    Peroxisomes are similar to lysosomes in that they contain hydrolytic enzymes.

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

    What is the main function of the enzyme catalase found in peroxisomes?

    <p>To convert hydrogen peroxide to water.</p> Signup and view all the answers

    What is the process called that degrades unneeded or damaged proteins by breaking peptide bonds?

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

    Which of the following is NOT a component of the cytoskeleton?

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

    Microtubules are visible under a light microscope.

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

    What are the basic building blocks of microtubules?

    <p>tubulin subunits (alpha and beta tubulin)</p> Signup and view all the answers

    What is the name given to the proteins that help stabilize microtubules?

    <p>microtubule-associated proteins (MAPs)</p> Signup and view all the answers

    Which of the following statements about microtubules is TRUE?

    <p>All of the above.</p> Signup and view all the answers

    What is the name given to the region where microtubules are formed and organized?

    <p>microtubule organizing center (MTOC)</p> Signup and view all the answers

    Microfilaments are composed of the protein tubulin.

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

    What is the name given to the network of microfilaments just beneath the cell membrane?

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

    Intermediate filaments are intermediate in diameter between microtubules and microfilaments.

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

    Which of the following is NOT a type of intermediate filament?

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

    What is the name given to the protein that intermediate filaments are made of in epithelial cells?

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

    Neurofilaments are a type of intermediate filament found in nerve cells.

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

    What is the name given to the structure made of intermediate filaments that lines the inner surface of the nuclear membrane?

    <p>nuclear lamina</p> Signup and view all the answers

    The nucleus is the largest organelle in a cell.

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

    Which of the following is NOT a component of the nucleus?

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

    What is the name given to the space between the inner and outer membranes of the nuclear envelope?

    <p>perinuclear space</p> Signup and view all the answers

    Which of the following describes euchromatin?

    <p>Loosely coiled, electron-sparse chromatin.</p> Signup and view all the answers

    What is the name given to the small, dense structure found within the nucleus that is involved in the synthesis of ribosomal RNA?

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

    The nucleolus is only present in cells that are actively synthesizing proteins.

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

    What is the name given to the gel-like substance that fills the space within the nucleus, excluding the chromatin and nucleolus?

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

    What is the main function of the nucleus?

    <p>To store and control the genetic information of the cell.</p> Signup and view all the answers

    Centrioles are paired, rod-like structures made up of nine microtubule triplets.

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

    What is the name given to the cellular region that includes the centrioles and pericentriolar material?

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

    Cytoplasmic inclusions are organelles with specialized functions.

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

    Which of the following is a type of cytoplasmic inclusion?

    <p>lipids droplets</p> Signup and view all the answers

    Glycogen granules are electron-dense structures that store glucose.

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

    What is the name given to the dark brown pigment found in skin cells that protects against ultraviolet radiation?

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

    Which of the following is a type of pigmented deposit found in cells?

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

    What is the name given to the dense brown pigment that contains denatured ferritin proteins and is often found in phagocytic cells?

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

    Crystals are a type of cytoplasmic inclusion that are commonly found in muscle cells.

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

    What type of cell is responsible for the production of testosterone in the testes?

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

    Study Notes

    Cytology - The Cell

    • Cells are the fundamental, functional units of tissues and the basic unit of life.
    • A cell consists of two main parts: cytoplasm and nucleus.

    Cytoplasm

    • Cytoplasm is composed of:

      • Cell organelles
      • Cell inclusions
      • Cytoskeleton
      • Cytosol

    • Organelles are classified as membranous or non-membranous based on the presence or absence of cell membranes.

    I. Membranous Organelles

    • Cell membrane
    • Mitochondria
    • Rough endoplasmic reticulum (RER)
    • Smooth endoplasmic reticulum (SER)
    • Golgi apparatus
      • Lysosomes
    • Peroxisomes
    • Secretory vesicles

    II. Non-Membranous Organelles

    • Ribosomes
    • Proteasomes
    • Cytoskeleton

    The Cell Membrane

    • The cell membrane separates the cytoplasm from surrounding structures.
    • It has selective permeability; regulating the entry and exit of compounds
    • Electron microscope (EM) is used to visualize the membrane, showing a trilaminar appearance.
    • Membranes are primarily composed of lipids, proteins, and carbohydrates.

    Lipids in Cell Membrane

    • The arrangement of lipid molecules (primarily phospholipids) forms the basic membrane framework.
    • Phospholipid molecules have a hydrophilic polar head and hydrophobic nonpolar tails.
    • In an aqueous environment, the hydrophilic heads face outward, and the hydrophobic tails face inward.
    • This arrangement creates the trilaminar appearance.
    • Lipids regulate the passage of water-soluble and nonpolar substances across the membrane.

    Proteins in Cell Membrane

    • Proteins are irregularly shaped and some span the entire membrane (transmembrane proteins).
    • Proteins have various functions, including:
      • Maintaining cell structure
      • Cell-cell adhesion
      • Transport across the membrane
      • Acting as receptors
      • Enzyme activity

    Carbohydrates in Cell Membrane

    • Carbohydrates are attached to proteins (glycoproteins) or lipids (glycolipids) on the external surface of the membrane.
    • This external carbohydrate layer forms the glycocalyx, which plays a role in cell adhesion and contains blood group antigens (in erythrocytes).

    Vesicular Transport

    • Macromolecules enter cells via endocytosis, involving membrane folds enclosing material.
    • Types of endocytosis include:
      • Phagocytosis ("cell eating")
      • Pinocytosis ("cell drinking")
      • Receptor-mediated endocytosis
    • Exocytosis is a vesicular transport process that releases materials from the cell.

    Cell Organelles

    • The cytoplasm houses various organelles with diverse functions.
    • These organelles can be membranous or non-membranous.

    1- Ribosomes

    • Non-membranous, small particles composed of rRNA and proteins.
    • Important in protein synthesis.
    • Can be free in the cytoplasm or attached to the rough endoplasmic reticulum (RER).

    2-Rough Endoplasmic Reticulum (RER)

    • An interconnected network of membranes with ribosomes attached to its surface.
    • Involved in protein synthesis and processing of proteins destined for secretion or incorporation into membranes.
    • Continuous with the nuclear envelope

    3-Smooth Endoplasmic Reticulum (SER)

    • An interconnected network of membranes without ribosomes.
    • Involved in lipid synthesis, metabolism of carbohydrates, detoxification of chemicals, and storage of calcium.
      • Usually more tubular than RER
    • Continuous with the RER

    4- Mitochondria

    • Bounded by a double membrane (outer and inner); highly folded inner membrane (cristae)
    • Important in cellular respiration and energy production (ATP synthesis).
    • Contain their own DNA and ribosomes.

    5-Golgi Complex

    • Stack of flattened, membrane-bound sacs.
    • Modifies, sorts, and packages proteins and lipids for secretion or delivery to other organelles.

    6- Secretory Vesicles

    • Membrane-bound sacs that store and transport cellular products outside or within the cell.

    7- Lysosomes

    • Membrane-bound vesicles containing digestive enzymes.
    • Involved in intracellular digestion and degradation of cellular waste.
    • Types include primary (containing only digestive enzymes), secondary (containing digested material)
    • Heterophagosome & Autophagosome refer to the type of secondary lysosome

    8- Peroxisomes

    • Membrane-bound vesicles containing enzymes involved in oxidation reactions, including the breakdown of hydrogen peroxide, which is toxic to the cell
    • Important in detoxification.

    9- Proteasomes

    • Protein complexes that break down unwanted or damaged proteins.

    The Cytoskeleton

    • A network of protein filaments that provides structural support and facilitates cellular movement.
    • Types of filaments include:
      • Microtubules: Hollow tubes made of tubulin, involved in cell shape, movement, and intracellular transport, found in centrioles and cilia.
      • Microfilaments (actin filaments): Thin filaments involved in cell movement, shape, and muscle contraction.
      • Intermediate filaments: Present in a variety of cell types, maintaining cell structure and providing strength.

    The Nucleus

    • The largest organelle in most cells.
    • Contains the genetic material (DNA) and controls cellular activities.
    • LM shows a central, denser region and
    • EM reveals specific components like the nuclear membrane, chromatin, nucleolus, and nucleoplasm.
    • Four main components: Nuclear membrane, chromatin, nucleolus, and nucleoplasm

    1- Nuclear membrane (or envelope)

    - Double-layered membrane surrounding the nucleus.
- Outer membrane is continuous with RER.
- The space between the membranes (perinuclear space) is continuous with the lumen of RER

    2- Chromatin

    - Composed of DNA and proteins.
- Consists of two types: euchromatin (loosely packed DNA) and heterochromatin (tightly packed DNA).

    3- Nucleolus

    • Dense structure found in the nucleus.
    • Primarily responsible for ribosomal RNA synthesis and ribosome assembly.

    4- Nucleoplasm

    - Viscous fluid filling the nucleus; containing various components.

    Cytoplasmic Inclusions

    • Accumulations of metabolites or other substances in the cytoplasm.
    • Not organelles; do not perform metabolic activities.
    • Examples include lipid droplets, glycogen granules, pigments, crystals etc.

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    Structure & Function Handbook 2024-2025 S1 Theoretical PDF

    Description

    Explore the fundamental concepts of cytology, focusing on the essential components of cells including cytoplasm and various organelles. This quiz covers both membranous and non-membranous organelles, as well as the structure and function of the cell membrane. Test your understanding of these vital units of life.

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