Cell Structure
Cells are the fundamental units of life, varying in shape, size, and function. They can be broadly classified into two categories: prokaryotic and eukaryotic cells.
Prokaryotic Cells
- Lack a defined nucleus.
- Smaller and simpler in structure.
- Example: Bacteria and Archaea.
Eukaryotic Cells
- Have a defined nucleus containing genetic material.
- Larger and more complex.
- Examples: Plant, animal, and fungal cells.
Cell Components
1. Cell Membrane
- A lipid bilayer that surrounds the cell, providing protection and regulating the movement of substances in and out.
2. Cytoplasm
- The jelly-like substance within the cell where organelles are suspended.
3. Nucleus
- Contains the cell's genetic material (DNA) and controls cellular activities.
4. Mitochondria
- Known as the powerhouse of the cell, they produce energy (ATP) through cellular respiration.
5. Ribosomes
- Sites of protein synthesis, found either floating freely in the cytoplasm or attached to the endoplasmic reticulum.
6. Endoplasmic Reticulum (ER)
- Rough ER: Studded with ribosomes, involved in protein synthesis and processing.
- Smooth ER: Lacks ribosomes, synthesizes lipids and detoxifies harmful substances.
7. Golgi Apparatus
- Modifies, sorts, and packages proteins and lipids for secretion or delivery to other organelles.
8. Lysosomes
- Contain enzymes for digestion of waste materials and cellular debris.
9. Chloroplasts (in plant cells)
- Sites of photosynthesis, converting sunlight into chemical energy.
Cell Function
Cells perform various functions essential for life, including metabolism, growth, reproduction, and response to stimuli. Understanding cell structure is crucial for studying biology and medicine, as it lays the foundation for cellular processes and interactions.