Cell Structure & Function Overview
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Questions and Answers

What is the primary function of the cell membrane?

  • To serve as a site for energy production
  • To store genetic information
  • To control the movement of substances in and out of the cell (correct)
  • To provide structural support to the cell

    • Which of the following best describes eukaryotic cells?

  • Cells that are only found in multicellular organisms
  • Cells that contain membrane-bound organelles (correct)
  • Cells that are always larger than prokaryotic cells
  • Cells that lack a nuclear membrane

    • What role do tissues play in the organization of the body?

  • They are formed by similar cells working together (correct)
  • They are responsible for waste disposal
  • They consist of different types of cells with varied functions
  • They provide nutrients to cells

    • Which of the following is NOT a characteristic of cells?

    <p>Cells are the largest structural units of life</p> Signup and view all the answers

    What does the Fluid Mosaic Model describe?

    <p>The arrangement of proteins and lipids in the cell membrane</p> Signup and view all the answers

    Which statement about prokaryotic cells is correct?

    <p>They lack a membrane-bound nucleus</p> Signup and view all the answers

    What type of inclusions might be found within the cytoplasm?

    <p>Fats and carbohydrates</p> Signup and view all the answers

    What are organ systems comprised of?

    <p>Groups of tissues working together</p> Signup and view all the answers

    What is the primary function of channel proteins in the plasma membrane?

    <p>To allow substances to flow in or out of the cell</p> Signup and view all the answers

    What characteristic of phospholipids allows the plasma membrane to be fluid and flexible?

    <p>The weak forces between phospholipid molecules</p> Signup and view all the answers

    What happens to a host cell if no antibodies interact with an exotoxin?

    <p>The host cell will die</p> Signup and view all the answers

    What function do receptors in the plasma membrane primarily serve?

    <p>Receive signals and respond to them</p> Signup and view all the answers

    What is the primary function of actin microfilaments in a cell?

    <p>Increasing surface area for absorption and secretion</p> Signup and view all the answers

    Which of the following statements accurately describes intermediate filaments?

    <p>They provide a supporting network within the cytoplasm.</p> Signup and view all the answers

    What type of transport allows molecules to move from high to low concentration without energy input?

    <p>Facilitated diffusion</p> Signup and view all the answers

    Which process involves a cell taking in solid food, such as bacteria?

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

    What role do microtubules play in cellular processes?

    <p>They facilitate the movement of chromosomes during cell division.</p> Signup and view all the answers

    What is the primary function of nuclear pores?

    <p>Allow movement of molecules across the nuclear envelope</p> Signup and view all the answers

    How do protein carriers function in the plasma membrane?

    <p>By changing shape to transport specific molecules</p> Signup and view all the answers

    What enzyme is associated with peroxisomes and what does it catalyze?

    <p>Catalase; decomposition of hydrogen peroxide</p> Signup and view all the answers

    What is the role of membrane proteins in maintaining a cell's homeostasis?

    <p>They act as receptors for hormones and chemical messengers</p> Signup and view all the answers

    What does the cytoplasm consist of?

    <p>Organelles and cytosol</p> Signup and view all the answers

    Which of the following structures is responsible for protein synthesis?

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

    Which cellular structure is primarily involved in transporting fluid across the cell surface?

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

    Which of the following describes active transport in cellular processes?

    <p>Movement against the concentration gradient</p> Signup and view all the answers

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

    <p>Control center of the cell</p> Signup and view all the answers

    Which statement about the nuclear envelope is correct?

    <p>It consists of two lipid bilayers</p> Signup and view all the answers

    What type of substances are cytoplasmic inclusions?

    <p>Small non-living substances</p> Signup and view all the answers

    How does the liver manage blood sugar levels?

    <p>By breaking down glycogen to glucose when blood sugar is low</p> Signup and view all the answers

    What is the primary function of lipids stored as triglycerides in liver cells?

    <p>To provide energy during fasting</p> Signup and view all the answers

    What role does the rough endoplasmic reticulum (ER) play in the cell?

    <p>Manufacture and transport proteins</p> Signup and view all the answers

    What is one of the main functions of the Golgi apparatus?

    <p>Storage and delivery of proteins</p> Signup and view all the answers

    Which organelle is primarily responsible for energy production?

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

    What process is primarily performed by lysosomes?

    <p>Digestion of microorganisms</p> Signup and view all the answers

    What distinguishes the smooth endoplasmic reticulum (SER) from the rough endoplasmic reticulum (RER)?

    <p>Function in detoxification and lipid synthesis</p> Signup and view all the answers

    What component is part of the cytoskeleton's function?

    <p>Maintains cell shape</p> Signup and view all the answers

    What is the main function of peroxisomes in a cell?

    <p>Detoxification of toxic substances</p> Signup and view all the answers

    Study Notes

    Introduction to the Cell

    • The cell is the smallest functional unit of the body.
    • Cells obtain nutrients from their surroundings, dispose of waste, maintain their structure, and replicate.

    Cell Structure & Function

    • Cell membrane (plasma membrane)
      • Composed of lipids and proteins.
      • Plays a crucial role in cell interaction with the environment and the transfer of nutrients and metabolites.
      • The Fluid Mosaic Model (Singer and Nicolson, 1972) describes the cell membrane as a bilayer of phospholipid molecules, with hydrophilic heads and hydrophobic tails.
      • Channel proteins: Allow substances to move in and out of the cell by controlling the movement of ions or molecules from high concentration to low.
      • Protein carriers: Change shape to transport substances across the membrane, selectively transporting molecules.
      • Receptors: Receive signals and respond to them, often glycoproteins.
      • Membrane proteins help maintain cell homeostasis, give the cell its immunological identity, and act as receptors for hormones and chemical messengers.
      • The plasma membrane regulates what enters and leaves the cell through:
        • Diffusion: Movement from high to low concentration (for gases and amino acids).
        • Osmosis: Diffusion specifically for water.
        • Endocytosis: Engulfing material by the cell:
          • Phagocytosis: Takes in solid food (e.g., bacteria).
          • Pinocytosis: Takes in fluid.
        • Exocytosis: Exporting material from the cell.

    Cell Transport

    • Passive transport (facilitated diffusion): Doesn't require energy, moves substances from high to low concentration (e.g., water, glucose, ions).
    • Active transport: Requires energy (ATP) to move substances against the concentration gradient (e.g., sodium ions out of the cell and potassium ions into the cell).

    The Nucleus

    • The largest organelle in the cell.
    • Contains the cell's genetic material.
    • Nuclear envelope: Consists of two layers that separate the nucleus from the cytoplasm.
      • The outer lipid bilayer is continuous with the rough endoplasmic reticulum.
      • The inner nuclear membrane contains a nuclear lamina made of polypeptides called lamins, adding mechanical support to the nucleus.
    • Nuclear pores: Allow the movement of molecules across the nuclear envelope.
    • The nucleus, together with ribosomes, is responsible for protein synthesis.

    The Cytoplasm

    • Surrounds the cell membrane.
    • Contains organelles and cytosol (intracellular fluid).
    • Cytoplasmic inclusions: Small, non-living substances within the cytosol, including:
      • Fats (lipids)
      • Pigments (melanin)
      • Crystals (protein, crystals of calcium phosphate)
      • Glycogen (in liver cells) - stores glucose and releases it to maintain blood sugar levels.
      • Lipids (in liver cells) - stores excess calories as triglycerides and releases them for energy when needed.

    Cytoplasmic Organelles

    • Each organelle has a specific function depending on the needs of each tissue.
    • Endoplasmic reticulum (ER): Network of membranes connected to the nuclear envelope.
      • Rough ER: Covered with ribosomes and responsible for protein production.
      • Smooth ER: Synthesizes lipids and carbohydrates, metabolizes them, stores calcium, and detoxes poisons and drugs.
    • Ribosomes: Composed of proteins and ribosomal RNA (rRNA), responsible for protein synthesis.
      • Polyribosomes: Clusters of ribosomes.
    • Golgi apparatus: Folded membranes that receive proteins synthesized in the rough ER, storing, packing, and delivering proteins when needed.
      • Secretory vesicles: Transport and process proteins and lipids.
    • Lysosomes: Type of secretory vesicle formed by the Golgi apparatus, containing enzymes for digesting microbes, RNA, DNA, carbohydrates, proteins, and pathogens.
      • Performs phagocytosis and exocytosis.
    • Mitochondria: Cellular power plants, with double-layered folded inner membranes and their own DNA, produce energy in the form of ATP.
    • Peroxisomes: Contain enzymes that convert toxic hydrogen peroxide to water, killing pathogens.
    • Cytoskeleton: Maintains cell shape, moves organelles, and determines cell polarity.
      • Actin microfilaments: Resist tension and maintain cell shape.
      • Intermediate filaments: Bind intracellular structures together and to the plasma membrane.
      • Microtubules: Made of contractile proteins involved in organelle movement, chromosome movement during cell division, and cell extension.
    • Cilia: Short, hair-like structures that move fluids across the cell surface, found for example in the fallopian tubes to transport eggs.

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    Cell Structure & Function PDF

    Description

    Explore the intricate world of cells as the smallest functional units of life. This quiz covers essential topics such as cell membranes, their compositions, functions, and the various proteins involved in cellular processes. Test your knowledge on how cells interact with their environment and maintain homeostasis.

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