Cell Theory Overview
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Questions and Answers

What is the primary function of chloroplasts in plant cells?

  • Assist in protein synthesis
  • Convert light energy into sugars (correct)
  • Convert nutrients into energy
  • Store genetic information

    • Which organelle is described as the 'powerhouse' of the cell?

  • Nucleolus
  • Golgi Apparatus
  • Ribosomes
  • Mitochondria (correct)

    • What is the primary role of lysosomes in animal cells?

  • Synthesize lipids
  • Digest and break down food (correct)
  • Fuel photosynthesis
  • Store carbohydrates and proteins

    • Which structure is essential for protein synthesis and is often associated with the rough endoplasmic reticulum (ER)?

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

    What role do microtubules play in animal cells?

    <p>Provide structure and aid in cell division</p> Signup and view all the answers

    What is the main function of the Golgi apparatus in cells?

    <p>Modify and package proteins</p> Signup and view all the answers

    What is the main function of peroxisomes in cells?

    <p>Digestion of nutrients and breakdown of toxins</p> Signup and view all the answers

    Which statement about vacuoles is true?

    <p>They store food and nutrients in the cell.</p> Signup and view all the answers

    What is a major difference between plant cells and animal cells?

    <p>Plant cells have cell walls.</p> Signup and view all the answers

    Which of the following is NOT a component that all cells share?

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

    In what stage of the cell cycle does the DNA synthesis occur?

    <p>S phase</p> Signup and view all the answers

    Which statement accurately describes prokaryotic cells?

    <p>Prokaryotes are older than eukaryotes.</p> Signup and view all the answers

    What occurs during the stage of cytokinesis?

    <p>The cytoplasm divides.</p> Signup and view all the answers

    Which phase takes up most of the cell's life?

    <p>G1 phase</p> Signup and view all the answers

    What is the correct sequence of stages during mitosis?

    <p>Prophase, Metaphase, Anaphase, Telophase</p> Signup and view all the answers

    What role do microtubules play during the cell cycle?

    <p>They help move chromosomes during mitosis.</p> Signup and view all the answers

    Who was the first individual to record the observation of cells?

    <p>Robert Hooke</p> Signup and view all the answers

    What are the three postulates of cell theory?

    <p>All living things are composed of one or more cells, cells are the basic unit of life, and all cells come from preexisting cells.</p> Signup and view all the answers

    Which scientist concluded that plants are made of cells?

    <p>Matthias Schleiden</p> Signup and view all the answers

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

    <p>Controls growth and reproduction.</p> Signup and view all the answers

    Which of the following organelles acts as a security guard for the cell?

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

    What does the term 'omnis cellula e cellula' imply?

    <p>All cells arise from preexisting cells.</p> Signup and view all the answers

    Which of the following best describes the cytoplasm?

    <p>It is a fluid that fills a cell and contains dissolved molecules.</p> Signup and view all the answers

    Which structure in plant cells provides protection and helps keep everything inside the cell?

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

    What is the primary role of the G1 checkpoint in the cell cycle?

    <p>To evaluate environmental conditions and cell health</p> Signup and view all the answers

    What occurs during the G2 checkpoint of the cell cycle?

    <p>DNA repair enzymes check for errors in replication.</p> Signup and view all the answers

    Which phase of meiosis involves the exchange of genetic material?

    <p>Prophase 1</p> Signup and view all the answers

    What is the main consequence of failed checkpoints in the cell cycle?

    <p>uncontrolled cell growth leading to cancer</p> Signup and view all the answers

    What happens during Metaphase 1 of meiosis?

    <p>Chromosomes align in pairs at the cell's center.</p> Signup and view all the answers

    What is the purpose of the Mitosis checkpoint?

    <p>To confirm that mitosis can proceed.</p> Signup and view all the answers

    Which statement correctly describes the result of Telophase 1 in meiosis?

    <p>Two haploid daughter cells are created.</p> Signup and view all the answers

    What stage occurs after Prophase 2 in meiosis?

    <p>Metaphase 2</p> Signup and view all the answers

    Study Notes

    Cell Theory

    • Cells are the fundamental building blocks of all living organisms, varying in shape and size.
    • Robert Hooke first observed cells in 1665 by examining cork through a microscope, coining the term “cellulae.”
    • Key contributors to cell theory: Theodor Schwann, Matthias Schleiden, Rudolph Virchow.
    • Three main postulates of cell theory:
      • All living things are made of one or more cells.
      • Cells are the basic unit of life.
      • All cells arise from preexisting cells.

    Discovery Timeline

    • Robert Hooke (1665): First recorded cells in cork.
    • Antoine van Leeuwenhoek (1660s): Observed protists and bacteria, describing them as "animacules."
    • Matthias Schleiden (1838): Established that all plants are composed of cells.
    • Theodor Schwann (1839): Stated that animals consist of cells and their products.
    • Robert Remak (1842): Identified three embryonic layers: ectoderm, mesoderm, endoderm.
    • Rudolph Virchow (1855): Concluded "omnis cellula e cellula" - all cells originate from existing cells.

    Organelles in Plant & Animal Cells

    • Organelles perform specific functions within cells and include:
      • Cell Membrane: Protective barrier assisting in transport.
      • Cell Wall (Plant): Provides structural protection.
      • Cytoplasm: Gel-like fluid containing dissolved substances.
      • Nucleus: Control center for growth and reproduction.
      • Nucleolus: Produces ribosomal RNA within the nucleus.
      • Chloroplast (Plant): Site of photosynthesis, converting sunlight to sugar.
      • Mitochondria: Energy production through cellular respiration.
      • Golgi Apparatus: Processes and packages proteins for export.
      • Smooth ER: Synthesizes and stores lipids.
      • Rough ER: Involved in protein synthesis with ribosomes.
      • Vacuole: Storage for nutrients and waste, larger in plants.
      • Ribosomes: Assemble proteins from amino acids.
      • Peroxisome: Breaks down fatty acids and detoxifies.
      • Lysosome (Animal): Digests macromolecules and recycles cellular waste.
      • Microtubules (Animal): Support structure and assist in cell division.
      • Centrioles (Animal): Aid in cell division; found in pairs.

    Cell Types

    • Organisms can be unicellular or multicellular, with humans composed of trillions of cells.
    • Two major cell types:
      • Prokaryotes: Simple, no membrane-bound organelles, no nucleus, oldest cell type (3.5 billion years).
      • Eukaryotes: Complex, membrane-bound organelles, contain a nucleus, appeared 1.5 billion years ago.
    • Similarities: Both have DNA and a cell membrane, containing essential biomolecules.
    • Differences: Eukaryotes are significantly larger than prokaryotes.

    Cell Cycle

    • Comprises three main stages: Interphase, Mitosis, Cytokinesis.
    • Interphase:
      • G1 Phase: Rapid growth and routine functions, longest duration.
      • S Phase: DNA replication occurs.
      • G2 Phase: Prepares for mitosis, assembles microtubules.
    • Mitosis: Division of the nucleus into two identical nuclei, includes prophase, metaphase, anaphase, and telophase.
    • Cytokinesis: Division of the cytoplasm resulting in two daughter cells.

    Control of the Cell Cycle

    • Three checkpoints monitor cell conditions:
      • G1 Checkpoint: Assesses size, health, and environmental factors before S phase.
      • G2 Checkpoint: Checks for DNA errors prior to mitosis.
      • Mitosis Checkpoint: Verifies successful completion of mitosis before returning to G1.
    • Checkpoint failures can lead to cancer or uncontrollable cell growth.

    Meiosis

    • A specialized type of cell division producing four haploid daughter cells (sex cells).
    • Ensures organisms from sexual reproduction have proper chromosome numbers.
    • Stages:
      • Prophase 1: Chromosome condensation and crossing over occur.
      • Metaphase 1: Chromosome pairs align randomly.
      • Anaphase 1: Chromosome pairs separate to opposite sides.
      • Telophase 1: New nuclei form, resulting in two haploid cells.
      • Prophase 2: Prepares for formation of four haploid cells.
      • Metaphase 2: Chromosomes align individually for separation in the next step.

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    Cell Theory PDF

    Description

    Explore the fundamental insights of cell theory, including the contributions of key scientists such as Robert Hooke, Theodor Schwann, Matthias Schleiden, and Rudolf Virchow. This quiz covers the postulates that define cells as the basic unit of life, emphasizing their role as the building blocks of all living organisms.

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