Basic Concepts
In a nutshell: Cells are the tiny building blocks that make up all living things and carry out essential life functions.
## Building Blocks of Life
All living things are made of cells, which are the basic units of life. Cells come in many shapes and sizes, but they all perform essential functions to keep organisms alive.
### Types of Cells
- **Prokaryotic cells:** Simple cells without a nucleus (like bacteria).
- **Eukaryotic cells:** More complex cells with a nucleus (like plant and animal cells).
### Main Cell Parts
- **Nucleus:** The control center, holding DNA.
- **Cytoplasm:** Jelly-like fluid where cell activities happen.
- **Cell membrane:** The skin that controls what enters and leaves.
- **Mitochondria:** The powerhouse, turning food into energy.
- **Chloroplasts:** Found only in plants, these turn sunlight into food.
## Cells at Work
Cells work together in tissues and organs, forming the complex structures of plants and animals.
Examples
- Your skin is made of millions of cells that protect your body.
- Leaves contain chloroplasts in their cells to make food through photosynthesis.
Key terms
- Mitochondria
- Organelles in cells that produce energy.
- Chloroplast
- An organelle in plant cells where photosynthesis happens.