Lecture Notes: Understanding Life in Biology

Introduction

• Start with a simple question: Why are certain organisms alive?
• Importance of asking foundational questions in biology.

Key Questions

• What makes something alive?
• What do biologists do about living organisms?
  • Describing and understanding them.

Definition of Life

• Key to life: Organization.
• Living things organized at various levels:
  • Subatomic particles (protons, neutrons, electrons)
  • Atoms
  • Molecules

Importance of Chemistry and Physics in Biology

• Understanding chemistry and physics is vital for biology.
• Living organisms are made of molecules, which are made of atoms, which are made of subatomic particles.
• Example: Squirming organisms are made of the same basic building blocks as humans.

The Secret of Life

• Life emerges from the organization of molecules into:
  • Organelles
  • Cells
  • Tissues
  • Organs
  • Organ systems
  • Multicellular organisms
• Importance of Orderly Organization: This is repeated throughout levels of biological organization.

Levels of Biological Organization

1. Cells: Basic unit of life.
2. Tissues: Groups of similar cells.
3. Organs: Structures made of tissues.
4. Organ Systems: Groups of organs performing related functions.
5. Multicellular Organisms: Organisms made of many cells.
6. Populations, Communities, Ecosystems, Environments: Larger biological units.

Ecological Perspective

• Current understanding of life is limited to Earth.
• Life exists in a thin layer around the Earth.
• Speculation about life in extreme environments (e.g., center of Earth).

Conclusion

• Describing living organisms helps understand the concept of life.
• Living organisms have a specific organization and capabilities that non-living things lack.