CELLS – THE BASIC UNIT OF LIFE
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In this chapter "Cell and Subcellular Organelles," we will do a detailed study of cells, the fundamental units that compose all living things. Building on your previous knowledge from Grade IX, we will explore the cell theory and examine the structures of both animal and plant cells. You'll also discover the vital processes of cell signalling, and the revolutionary potential of stem cells. Additionally, we will investigate the mechanisms of membrane transport that are crucial for cellular function.
3.1- CELLS – THE BASIC UNIT OF LIFE
Cells are the basic unit of life, making up every living organism. In unicellular organisms like amoebas and bacteria, a single cell carries out all the functions necessary for life. Multicellular organisms, such as plants and animals, are composed of numerous specialized cells that work together to sustain life. You know that all living organisms show the seven basic properties of life i.e., movement, respiration, homeostasis, growth, reproduction, excretion, and nutrition. These properties actually define living organisms. Cells perform all the fundamental activities that characterize living organisms.
1. Movement: Cells can move. For example, sperm cells move with their flagella. White blood cells travel through the bloodstream to fight infections. Inside cells, organelles move to carry out vital functions.
2. Nutrition: Cells obtain nutrients from their environment to produce energy, build cellular structures, and drive biochemical reactions.
3. Respiration: Cells generate energy through respiration. This process breaks glucose to release ATP, the energy currency that powers cellular activities.
4. Excretion: Cells remove waste products through diffusion and active transport, preventing toxic buildup.
5. Homeostasis: Cells maintain a stable internal environment by regulating the movement of substances across their membranes.
6. Growth: Cells grow by taking in nutrients and converting them into cellular components.
7. Reproduction: Cells reproduce through mitosis and meiosis. Mitosis produces identical daughter cells for growth and repair, while meiosis creates gametes for sexual reproduction.
Cells and Subcellular Organelles
- Introduction to Cells
- Cells: Basic unit of life
- Unicellular organisms: One cell functions for life
- Multicellular organisms: Specialized cells work together
- Seven Basic Properties of Life
- Movement
- Cells can move (e.g., sperm flagella, white blood cells)
- Nutrition
- Cells obtain nutrients for energy and structure
- Respiration
- Cells produce energy (ATP) through respiration
- Excretion
- Cells eliminate waste via diffusion, active transport
- Homeostasis
- Cells maintain stable internal environment
- Growth
- Cells grow by converting nutrients into components
- Reproduction
- Mitosis: Identical daughter cells (growth, repair)
- Meiosis:
- Gametes for sexual reproduction
- Movement
- Cells: Key Functions
- Cells perform all life-defining activities:
- Movement: Organelles move within cells
- Nutrition: Intake nutrients for biochemical reactions
- Energy: ATP generated through respiration
- Waste: Excretion to prevent toxicity
- Regulation: Maintain stable internal environment
