Cell Theory and Characteristics
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Questions and Answers

How many chromosomes are present in each human cell?

  • 92 chromosomes
  • 46 chromosomes (correct)
  • 44 chromosomes
  • 23 chromosomes

    • What is a characteristic of anucleated cells?

  • They contain one nucleus
  • They contain multiple nuclei
  • They are incapable of dividing (correct)
  • They can divide into daughter cells

    • What type of cell becomes polynucleated during development in humans?

  • Blood cells
  • Nerve cells
  • Epithelial cells
  • Skeletal muscle cells (correct)

    • What is the role of the nucleus in a eukaryotic cell?

    <p>Stores DNA and directs cell activities</p> Signup and view all the answers

    What initiates the breakdown of the nucleus?

    <p>Cell division and apoptosis</p> Signup and view all the answers

    What type of cancer is associated with multinucleated giant cells?

    <p>Giant-cell tumor of the bone</p> Signup and view all the answers

    Which is a function of RNA polymerases in the nucleus?

    <p>Synthesize RNA molecules</p> Signup and view all the answers

    What disorder may be linked to defective nucleoli?

    <p>Alzheimer’s disease</p> Signup and view all the answers

    Which organelle is known as the site of ribosome synthesis?

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

    What is the role of the nuclear membrane?

    <p>Protect the nucleus contents</p> Signup and view all the answers

    What type of chromatin is considered less compact and routinely expressed within the cell?

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

    Which structure within the nucleus is composed of rRNA and proteins?

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

    What forms when chromatin condenses during cell division?

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

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

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

    Which organelle is involved in the synthesis, storage, and export of molecules in a cell?

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

    What is the function of nuclear pores in the nuclear membrane?

    <p>To permit exchange with cytoplasm</p> Signup and view all the answers

    What are anti-nuclear antibodies (ANA) associated with?

    <p>Autoimmune diseases</p> Signup and view all the answers

    What is the primary function of the smooth endoplasmic reticulum?

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

    Which type of endoplasmic reticulum is embedded with ribosomes?

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

    What substance does the cytoplasm primarily consist of?

    <p>Mineral salts and water</p> Signup and view all the answers

    How does the rough endoplasmic reticulum assist with protein management?

    <p>It directs proteins to the Golgi apparatus</p> Signup and view all the answers

    What role does the endoplasmic reticulum play in the cell?

    <p>Biosynthetic activities and protein processing</p> Signup and view all the answers

    Which of the following is NOT a function of the smooth endoplasmic reticulum?

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

    What does the smooth endoplasmic reticulum help detoxify?

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

    What directs proteins to the endoplasmic reticulum (ER)?

    <p>An N-terminal signal sequence</p> Signup and view all the answers

    What are the three main structures observed in the Golgi apparatus under electron microscopy?

    <p>Flattened vesicles, secretory vesicles, and microvesicles</p> Signup and view all the answers

    Which side of the Golgi apparatus acts as a receiving dock for products?

    <p>Cis-face</p> Signup and view all the answers

    What happens to products as they travel through the Golgi apparatus?

    <p>They are modified and prepared for shipment</p> Signup and view all the answers

    What consequence can result from defects in Golgi function?

    <p>Various disorders including muscular dystrophy and cancer</p> Signup and view all the answers

    What is the smallest structural and functional unit of organisms?

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

    Which of the following characteristics is NOT associated with cells?

    <p>Compose tissues</p> Signup and view all the answers

    Which of the following statements about prokaryotic cells is true?

    <p>They are always unicellular.</p> Signup and view all the answers

    What is the primary function of the nucleus in a cell?

    <p>Control center containing DNA</p> Signup and view all the answers

    What is a key difference between prokaryotic and eukaryotic cells?

    <p>Prokaryotic cells lack membrane-bound organelles.</p> Signup and view all the answers

    What process do all cells undergo to duplicate?

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

    Which of the following contains the liquid cytosol and organelles?

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

    Which statement correctly describes ribosomes in prokaryotic cells?

    <p>They are smaller than those in eukaryotic cells.</p> Signup and view all the answers

    Study Notes

    Cell Theory

    • Cells serve as the fundamental structural and functional units of living organisms.
    • Every organism is made up of one or more cells.
    • Cells originate solely from preexisting cells through cell division.

    Characteristics of a Cell

    • Capable of storing genetic information.
    • Engages in energy production and utilization.
    • Exhibits movement abilities.
    • Senses and responds to environmental stimuli.
    • Undergoes duplication for growth, repair, reproduction, and development.
    • Maintains homeostasis through self-regulation.
    • Synthesizes essential molecules like proteins, carbohydrates, fats, and nucleic acids.

    Types of Cells

    • Prokaryotic Cells: Lack a true nucleus and membrane-bound organelles. Generally unicellular, with DNA as a single circular strand.
    • Eukaryotic Cells: Possess a true nucleus and membrane-bound organelles. Can be unicellular or multicellular, containing multiple linear DNA strands with associated proteins.

    Prokaryotes vs. Eukaryotes

    • Size: Prokaryotic cells are typically less than 10 µm; eukaryotic cells range from 10 to 100 µm.
    • Nucleus: Prokaryotes lack a true nucleus, while eukaryotes have a membrane-bound nucleus.
    • Organelles: Prokaryotes have no membrane-bound organelles; eukaryotes do.
    • DNA: Prokaryotes' DNA is circular and non-associated with proteins; eukaryotes' DNA is linear and protein-associated.
    • Ribosome Size: Prokaryotic ribosomes are small, whereas eukaryotic are larger.
    • Reproduction: Prokaryotes reproduce only asexually via binary fission; eukaryotes can reproduce sexually or asexually through mitosis and meiosis.

    Three Important Cell Regions

    • Cell Membrane: The outer boundary protecting the cell.
    • Nucleus: The control center containing DNA, regulating cell function.
    • Cytoplasm: The gel-like substance between the nucleus and cell membrane where organelles are suspended.

    Organelles of the Cell

    • Connected through the endomembrane system.
    • Function collectively in synthesis, storage, and export of molecules.

    The Nucleus

    • Largest organelle in animal cells, composed of:
      • Nuclear Membrane: Double-layered, containing nuclear pores for substance exchange.
      • Nucleoplasm: The liquid similar to cytosol in the cytoplasm.
      • Nucleolus: Site of ribosome synthesis, composed of rRNA and proteins.
      • Chromatin and Chromosomes: DNA wrapped around histones; forms chromosomes during cell division.

    Chromosome Structure

    • Composed of nucleosomes (DNA wrapped around histones) and coiling into chromatin fibers for structure during cell division.
    • Each human cell typically contains 46 chromosomes.

    Cell Types

    • Anucleated Cells: Lack a nucleus, unable to divide.
    • Polynucleated Cells: Contain multiple nuclei; common in skeletal muscle cells and sometimes in pathological conditions.

    Function of the Nucleus

    • Stores DNA, directs cell activities including replication, repair, and transcription.
    • Contains specific enzymes for transcription and regulation.
    • Small molecules enter freely; macromolecules require regulated transport through nuclear pores.

    Cytoplasm

    • Jelly-like medium where biochemical reactions occur.
    • Contains enzymes, substrates, waste products, and organelles.

    Endoplasmic Reticulum (ER)

    • Network of membranes spread throughout the cytoplasm.
    • Smooth ER: Involved in lipid synthesis, detoxification, and calcium ion storage.
    • Rough ER: Studded with ribosomes, involved in protein synthesis, storage, and transport to the Golgi apparatus.

    Golgi Apparatus

    • Functions as a molecular warehouse and processing center.
    • Consists of flattened membrane vesicles (saccules) with a cis (receiving) and trans (shipping) face.
    • Modifies products received from the ER for transport.

    Golgi Functions

    • Ships proteins, storage vacuoles, and lysosomes.
    • Errors in Golgi function lead to various disorders, including congenital glycosylation disorders, muscular dystrophy, diabetes, cancer, and cystic fibrosis.

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    Description

    Explore the fundamentals of cell theory and the essential characteristics that define cells. Understand the differences between prokaryotic and eukaryotic cells and their roles in living organisms. This quiz will test your knowledge of cellular structure and function.

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