Cell Biology Overview
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Which of the following is NOT one of the three main regions of a cell?

  • Cytoplasm
  • Plasma membrane
  • Nucleus
  • Mitochondria (correct)

    • What was the original reason Robert Hooke named the structures he observed as 'cells'?

  • They resembled the rooms of a monastery. (correct)
  • They contained living microorganisms.
  • They were the smallest units of life.
  • They were found in plant tissue only.

    • The principle of complementarity of structure and function suggests that:

  • The activities of cells are independent of their shape.
  • Cells can change their shape to perform different functions.
  • The biochemical activities of cells depend on their shapes and structures. (correct)
  • Only certain cell types can maintain life.

    • Which of the following statements about cells is true?

    <p>Cells are the simplest units of living matter.</p> Signup and view all the answers

    How do the activities of an organism relate to its cells?

    <p>They depend on both individual and collective cell activities.</p> Signup and view all the answers

    Which concept is included in the cell theory?

    <p>The shape of a cell determines its function.</p> Signup and view all the answers

    What marks the continuity of life from one generation to another?

    <p>The ability to reproduce cells.</p> Signup and view all the answers

    What is primarily contained within a cell?

    <p>Various organelles and cytoplasm.</p> Signup and view all the answers

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

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

    What happens to chromatin when a cell prepares to divide?

    <p>It condenses to form chromosomes</p> Signup and view all the answers

    Which component of the plasma membrane is responsible for membrane fluidity?

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

    What role does the nuclear membrane play in the cell?

    <p>Acts as a barrier with nuclear pores</p> Signup and view all the answers

    How do organ systems interact within the body?

    <p>They collaborate to promote body well-being</p> Signup and view all the answers

    What is primarily contained within the nucleoli?

    <p>Ribosomal RNA and proteins</p> Signup and view all the answers

    What structural feature distinguishes the double phospholipid layer of the plasma membrane?

    <p>Hydrophilic heads and hydrophobic tails</p> Signup and view all the answers

    What function does the cell membrane serve?

    <p>Acts as a barrier for cell contents</p> Signup and view all the answers

    What type of cartilage is characterized by its elasticity and supports the external ear?

    <p>Elastic cartilage</p> Signup and view all the answers

    Which type of connective tissue is highly compressible and forms cushion-like discs between vertebrae?

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

    What is the primary matrix element in dense connective tissue?

    <p>Collagen fibers</p> Signup and view all the answers

    Which type of connective tissue is characterized by its soft, pliable nature and ability to soak up excess fluid?

    <p>Areolar connective tissue</p> Signup and view all the answers

    Which of the following is a function of adipose tissue?

    <p>Insulates the body</p> Signup and view all the answers

    What type of muscle tissue is found only in the heart and is responsible for pumping blood?

    <p>Cardiac muscle</p> Signup and view all the answers

    What is the primary purpose of cell division?

    <p>To produce more cells for growth and repair</p> Signup and view all the answers

    During which phase of the cell cycle does DNA replication occur?

    <p>In interphase</p> Signup and view all the answers

    Which type of connective tissue forms the stroma of lymphoid organs such as lymph nodes and spleen?

    <p>Reticular connective tissue</p> Signup and view all the answers

    What is a characteristic feature of skeletal muscle cells?

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

    What is the outcome of mitosis?

    <p>Formation of two daughter nuclei</p> Signup and view all the answers

    In which stage of mitosis are chromosomes aligned in the center of the cell?

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

    What is a gene?

    <p>A DNA segment that carries a blueprint for building one protein</p> Signup and view all the answers

    What role does RNA play in protein synthesis?

    <p>It carries amino acids to the ribosome</p> Signup and view all the answers

    What structure begins to form during telophase?

    <p>Cleavage furrow</p> Signup and view all the answers

    What is the building block of proteins?

    <p>Amino acids</p> Signup and view all the answers

    What happens to liver cells in terms of division when they are mature?

    <p>They can divide but only under certain conditions.</p> Signup and view all the answers

    Which of the following factors is NOT mentioned as a potential cause of aging?

    <p>High levels of physical activity.</p> Signup and view all the answers

    How does aging affect epithelial membranes?

    <p>They lose their elasticity and become damaged more easily.</p> Signup and view all the answers

    What is the primary consequence when cardiac muscle cells are damaged?

    <p>They are replaced by non-functional scar tissue.</p> Signup and view all the answers

    What is a characteristic of amitotic tissues?

    <p>They lose the ability to divide when mature.</p> Signup and view all the answers

    What happens to the body's hormone production as it ages?

    <p>Some endocrine glands decrease their hormone production.</p> Signup and view all the answers

    What is a common change observed in connective tissue with aging?

    <p>Porosity increases, leading to weakness.</p> Signup and view all the answers

    What term is used to describe an abnormal mass of proliferating cells?

    <p>Neoplasm.</p> Signup and view all the answers

    Study Notes

    Cell Theory

    • The cell is the basic structural and functional unit of living organisms.
    • The activity of an organism depends on the collective activities of its cells.
    • The continuity of life from one generation to another has a cellular basis.

    Cell Structure

    • Cells are organized into three main regions:
      • Nucleus
      • Cytoplasm
      • Plasma membrane

    Nucleus

    • The nucleus is the control center of the cell.
    • It contains genetic material (DNA).
    • It has three regions:
      • Nuclear membrane
      • Nucleolus
      • Chromatin

    Nuclear Membrane

    • The nuclear membrane is a barrier for the nucleus.
    • It consists of a double phospholipid membrane.
    • It contains nuclear pores that allow for the exchange of material with the rest of the cell.

    Nucleoli

    • The nucleus contains one or more nucleoli.
    • Nucleoli are the sites of ribosome production.
    • Ribosomes migrate to the cytoplasm through nuclear pores.

    Chromatin

    • Chromatin is composed of DNA and protein.
    • It's scattered throughout the nucleus.
    • Chromatin condenses to form chromosomes when the cell divides.

    Plasma Membrane

    • The plasma membrane is a barrier for cell contents.
    • It's a double phospholipid layer with hydrophilic heads and hydrophobic tails.
    • The plasma membrane also consists of proteins, cholesterol, and glycoproteins.

    Functions of a Cell

    • Reproduction by cell division.
    • Utilization of enzymes and other proteins coded by DNA genes and made via messenger RNA intermediates and ribosomes.
    • Metabolism.
    • Response to external and internal stimuli, such as change in temperature, pH, or levels of nutrients.
    • Cell contents are contained within a cell surface membrane made of a phospholipid bilayer with embedded proteins.

    DNA Replication

    • Genetic material gets duplicated.
    • This readies a cell for division into two cells.
    • It occurs toward the end of interphase.
    • DNA uncoils and each side serves as a template.

    Cell Division

    • Cell division is the process by which a cell replicates itself.
    • Has two main stages:
      • Mitosis (division of the nucleus).
      • Cytokinesis (division of the cytoplasm).

    Stages of Mitosis

    • Interphase: No cell division occurs, the cell carries out normal metabolic activity and growth.
    • Prophase: The first part of cell division, centromeres migrate to the poles.
    • Metaphase: The spindle fibers from the centromeres are attached to chromosomes aligned in the center of the cell.
    • Anaphase: Daughter chromosomes get pulled toward the poles, and the cell begins to elongate.
    • Telophase: Daughter nuclei begin forming, and a cleavage furrow begins to form for cell division.

    Protein Synthesis

    • Proteins are essential for all aspects of cell life.
    • The DNA blueprints, known as genes, are essential for protein synthesis.
    • The process of protein synthesis is known as translation.
    • RNA is essential for protein synthesis, acting as a messenger between DNA and ribosomes.
    • Proteins have many functions:
      • Building material for cells (fibrous or structural proteins).
      • Biological catalysts (enzymes), which speed up chemical reactions that occur in cells.

    Connective Tissue Types

    • Connective tissue is a type of tissue that supports and binds other tissues.
    • Types of connective tissue:
      • Cartilage: Supports and protects tissues, found in the nose, ears, and joints.
        • Hyaline cartilage (smooth, glassy, found in joints).
        • Elastic cartilage (provides elasticity, found in external ear).
        • Fibrocartilage (highly compressible, forms cushions between vertebrae).
      • Dense connective tissue: Main matrix element is collagen fibers, cells are fibroblasts. Examples include tendons and ligaments.
      • Areolar connective tissue: Most widely distributed connective tissue, soft, pliable, contains all fiber types, can soak up excess fluid.
      • Adipose tissue: Matrix is an areolar tissue where fat globules predominate. Many cells contain large lipid deposits. Functions include insulation, protection, and fat storage.
      • Reticular connective tissue: Forms a delicate network of interwoven fibers, forms the stroma (internal supporting network) of organs like lymph nodes, spleen, and bone marrow.
      • Blood: Blood cells surrounded by a fluid matrix, fibers are visible during clotting. It serves as a transport vehicle for materials.

    Muscle Tissues

    • Muscle tissue is the only tissue that can produce movement.
    • Types of muscle tissue:
      • Skeletal muscle: Controlled voluntarily, cells attach to connective tissue, striated, cells have more than one nucleus.
      • Cardiac muscle: Found only in the heart, functions to pump blood involuntarily, cells attached to other cardiac muscle cells at intercalated disks, striated, one nucleus per cell.
      • Smooth muscle: Found in walls of hollow organs like the stomach and intestines, involuntary, lacks striations, one nucleus per cell.

    Developmental Aspects of Tissues

    • Liver cells stop dividing but retain the ability to divide if damaged for repair.
    • Heart muscle and nervous tissue become amitotic (lose the ability to divide) when fully mature.
    • Amitotic tissues cannot regenerate when damaged.
    • The aging process begins after maturity.
    • Certain events are part of the aging process:
      • Epithelial membranes thin and are more easily damaged.
      • Skin loses elasticity and begins to sag.
      • Exocrine glands become less active, leading to dryness.
      • Endocrine glands produce fewer hormones, slowing body processes.
      • Connective tissue structures change with age:
        • Bones become weak.
        • Tissue repair is slower.
        • Muscles start to waste away.
    • Decreased efficiency of the circulatory system, affecting nutrient and oxygen delivery to body tissues, is a contributing factor to age-related changes.
    • Abnormal cell growth can lead to a neoplasm (new growth), which can be benign or malignant.

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    Unit III. The Cell and Tissues PDF

    Description

    Explore the fundamental concepts of cell theory and structure in this quiz. Learn about the roles of the nucleus, nuclear membrane, nucleoli, and chromatin in cellular function. Test your knowledge on how these components contribute to the continuity of life.

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