Structure of a Cell
🔍 Main Parts of a Cell
Every cell, whether plant or animal, has three basic parts:
🟠 1. Cell Membrane (Plasma Membrane)
- It is the outermost living layer of an animal cell.
- Made up of lipids and proteins.
- It is selectively permeable – allows only certain substances to pass through.
- Controls entry and exit of materials.
🧠 In plant cells, it is present just inside the cell wall.
🟢 2. Cytoplasm
- A jelly-like fluid that fills the cell.
- Located between the cell membrane and the nucleus.
- Contains cell organelles (mitochondria, ER, Golgi, etc.).
- Site of metabolic activities like respiration, synthesis, etc.
🟣 3. Nucleus – The Brain of the Cell
- Located in the center of the cell (peripheral in plant cells).
- Enclosed by a double membrane called the nuclear envelope.
- Contains:
- Nucleoplasm – fluid inside the nucleus
- Nucleolus – helps in making ribosomes
- Chromatin – thread-like structures that form chromosomes during cell division
- Controls all cellular activities and stores genetic material (DNA).
🧬 Chromosomes and DNA
- Chromosomes are made of DNA (Deoxyribonucleic Acid) and proteins.
- They carry hereditary information from parents to offspring.
- Humans have 23 pairs (46 chromosomes) in each body cell.
🌱 Extra in Plant Cells – Cell Wall
- A rigid outer covering found only in plant cells.
- Made of cellulose.
- Provides shape and protection to the cell.
- Lies outside the plasma membrane.
📌 Quick Recap: Cell Structure
| Part | Description | Function |
|---|---|---|
| Cell Membrane | Outer covering of the cell | Controls movement of substances |
| Cytoplasm | Jelly-like fluid | Site of chemical reactions |
| Nucleus | Central control unit | Controls activities, contains DNA |
| Cell Wall (Plant Only) | Rigid outer layer | Protection and shape |
| Chromosomes | Thread-like DNA structures | Carries genetic info |
🧠 Think & Explore
- 👉 What happens if the cell membrane is damaged?
- 👉 Why is the nucleus called the brain of the cell?