Subtopic 2.1: Cell Structure and Function – Chapter 2: Cell Biology and Organization – Biology Form 4 KSSM

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Learning Standards

  1. Prepare Microscope Slides:

    • Develop skills to prepare slides of animal and plant cells.

  2. Identify Structures:

    • Recognize and identify the structures of animal and plant cells through a light microscope.

  3. Analyze Cell Components:

    • Examine and analyze the components of animal and plant cells as seen in micrographs.

  4. State Functions:

    • Understand and state the main functions of the cell components.

  5. Compare and Contrast:

    • Differentiate between animal and plant cells based on their structures and functions.

Introduction

  • Every cell in your body is aware of how you think and feel about yourself.
  • Cells know what is happening in the body, so understanding them is crucial.
  • You have prepared and examined slides of plant cells in previous classes, like onion cells in Form 1.
  • For animal cells, cheek cells are commonly used, stained with blue dye to make structures visible.

Microscope Slide Preparation

  • Plant Cells:
    • Example: Onion cells.
    • Visible structures: Cell wall, nucleus, and sometimes the vacuole depending on staining quality.
  • Animal Cells:
    • Example: Cheek cells.
    • Visible structures: Plasma membrane and nucleus.

Cell Theory

  • Robert Hooke: First microscopic observation of plant tissue.
  • Cell Theory States:
    1. All organisms are made up of one or more cells.
    2. Cells are the basic units of structure and function in all organisms.
    3. All cells arise from pre-existing cells.

Types of Cells

  1. Prokaryotic Cells:

    • Lack a nucleus.
    • Example: Bacteria.

  2. Eukaryotic Cells:

    • Contain a nucleus.
    • Examples: Protists, fungi, animals, and plants.

Components and Functions of Animal and Plant Cells

  • Cell Membrane:

    • A thin, semi-permeable membrane made up of proteins and lipids.
    • Controls the movement of substances in and out of the cell.

  • Cytoplasm:

    • A jelly-like fluid that fills the cell.
    • Contains all organelles and cell parts.
    • Site of most cellular activities.

  • Nucleus:

    • The control center of the cell.
    • Contains DNA and regulates cell activities.

  • Cell Wall (Plant Cells Only):

    • A rigid layer made of cellulose.
    • Provides structural support and protection.
    • Fully permeable to allow substances to pass through.

  • Chloroplast (Plant Cells Only):

    • Contains chlorophyll, the green pigment.
    • Site of photosynthesis, where light energy is converted into chemical energy.

  • Endoplasmic Reticulum (ER):

    • Rough ER: Studded with ribosomes, involved in protein synthesis and transport.
    • Smooth ER: Lacks ribosomes, involved in lipid synthesis and detoxification.

  • Ribosomes:

    • Small structures that synthesize proteins.
    • Found on the rough ER and in the cytoplasm.

  • Golgi Apparatus:

    • Modifies, sorts, and packages proteins and lipids for storage or transport out of the cell.

  • Mitochondria:

    • Known as the powerhouse of the cell.
    • Generates energy (ATP) through the process of cellular respiration.

  • Lysosomes:

    • Contains digestive enzymes to break down waste materials and cellular debris.

  • Vacuole (Plant Cells Only):

    • A large, central sac that stores water, nutrients, and waste products.
    • Helps maintain cell turgidity.

  • Centrioles (Animal Cells Only):

    • Involved in cell division.
    • Help organize the assembly of microtubules during cell division.

Comparison of Animal and Plant Cells

  • Similarities:
    • Both have a nucleus, cytoplasm, plasma membrane, Golgi apparatus, mitochondria, endoplasmic reticulum (smooth and rough), and ribosomes.
  • Differences:
    • Animal Cells:
      • Have centrioles.
    • Plant Cells:
      • Have a cell wall, chloroplasts, and a large central vacuole.

Additional Resources

  • Educational Videos: Watch videos linked in the description for visual understanding and reinforcement of concepts.
  • Formative Assessment: Engage in activities and questions to test your understanding.

Quick Questions

  1. Function of the Electron Microscope:

    • Provides high magnification and resolution, allowing detailed study of cell structures.

  2. Chloroplast Presence:

    • Found in green plants, where photosynthesis occurs.
    • Absent in non-green plants, e.g., root cells which do not perform photosynthesis.

Conclusion

  • Understanding cell structure and function is fundamental to biology.
  • Performing experiments and utilizing visual aids like videos can greatly enhance comprehension.

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