CELL-THEORY

Learning Competency

  • Explains the postulates of the Cell Theory (STEM BIO11/12-la-c-1)

What is BIOLOGY?

  • Derived from the Greek words "BIOS" (meaning LIFE) and "LOGOS" (meaning STUDY)

  • A branch of knowledge focused on living organisms.

  • Defined as the science of life or living matter regarding origin, growth, reproduction, structure, and behavior.

  • Encompasses the study of all life forms from unicellular organisms to complex beings like humans.

Classification of Things

Living Things

  • Protists

  • Plants

  • Animals

  • Fungi

  • Bacteria

Non-Living Things

  • Soil

  • Water

  • Air

  • Light

  • Minerals

Characteristics of Living Things

  • Respiration: Process of energy production.

  • Movement: Ability to change position.

  • Response to Stimuli: Reaction to environmental changes.

  • Growth: Increase in size and mass.

  • Reproduction: Ability to produce offspring, requires DNA.

  • Dependency: Reliance on surroundings.

Detailed Characteristics of Life

  • Cell Composition:

    • Composed of cells, unicellular organisms (e.g., bacteria) vs. multicellular organisms (e.g., humans).

  • Cellular Organization:

    • Different levels of cellular organization exist in life forms.

  • Energy Usage (Metabolism):

    • Living things require energy for metabolic processes like movement and reproduction.

    • Metabolism refers to all biochemical reactions occurring within cells.

  • Homeostasis:

    • Regulation of the internal environment for stability, despite external changes.

  • Growth:

    • Growth utilizes energy from metabolism.

  • Reproduction:

    • Can be asexual or sexual, involving transfer or copying of DNA.

  • Response to Environment:

    • Organisms respond to environmental stimuli like light, temperature, and moisture.

  • Adaptation:

    • Genetic changes enabling survival in specific environments.

  • Death:

    • All living things eventually die.

Structure and Organization of Life

  • CELL: The smallest living unit in organisms.

  • TISSUE: A group of similar cells performing a specific function.

    • Types: Epithelial, Connective, Muscle, Nervous.

      • Epithelial Tissue: Covers surfaces and lines cavities; functions in protection and secretion.

      • Connective Tissue: Binds other tissues; supports organs, stores fats, and transfers substances.

      • Muscle Tissue: Generates movement; categories include skeletal, smooth, and cardiac muscle.

      • Nervous Tissue: Coordinates body functions; responsible for sensations and processing information.

  • ORGAN: A collection of tissues working together for a specific function.

  • ORGAN SYSTEM: A grouping of organs coordinating to perform complex functions.

    • Examples include:

      • Cardiovascular System: Transports oxygen and nutrients.

      • Lymphatic System: Defends against disease.

      • Digestive System: Processes food and absorbs nutrients.

      • Endocrine System: Regulates long-term body changes via hormones.

      • Integumentary System: Protects from injury and infection.

      • Other Systems include Muscular, Nervous, Reproductive, Respiratory, Skeletal, Urinary, and Immune Systems.

Levels of Biological Organization

  • Organism: A living being composed of various organs.

  • Population: Groups of individuals of the same species in an area.

  • Community: All different populations living and interacting in a given area.

  • Ecosystem: Organisms interacting with their physical surroundings.

  • Biosphere: The global ecological system integrating all ecosystems.

Cell Discovery and Theory

  • Historical Figures:

    • Zacharias Janssen (1595): Invented the first compound microscope.

    • Robert Hooke (1665): Observed cork and coined the term "cellulae."

    • Anton van Leeuwenhoek (1667): Improved microscope; described various microorganisms.

Development of Cell Theory

  • Schleiden (1838): Proposed that all plants are made of cells.

  • Schwann (1839): Stated all animals are composed of cells.

  • Virchow (1858): Claimed cells arise from pre-existing cells.

Postulates of Cell Theory

  1. All organisms are composed of cells.

  2. The basic unit of life is the cell.

  3. Cells arise from pre-existing cells.

Disproving Spontaneous Generation

  • Francisco Redi (1668): Conducted experiments with meat in jars, showing maggots only appeared in open jars.

  • Lazzaro Spallanzani (1799): Showed that boiled broth remains sterile in sealed containers.

  • Louis Pasteur (1859): Proved that microorganisms contaminate sterilized broth when exposed to air.

Educational Activity: Cell Theory in Action

  1. Prepare materials: 3 glass jars, fresh meat or fruit.

  2. Place the sample in jars - keeping one open, another covered with gauze, and the last sealed.

  3. Observe and record maggot formation to conclude on spontaneous generation.

Conclusion

  • The study of life incorporates understanding living organisms and their interactions within ecosystems, culminating in the development of crucial theories such as the Cell Theory and disproving earlier misconceptions like spontaneous generation.