Summary of "Characteristics of Life"

Characteristics of Life

Organization:
- Living organisms are made of cells (cell theory).
- Organisms can be unicellular (single cell) or multicellular (many cells organized into tissues, organs, and systems).
Homeostasis:
- The ability to maintain a stable internal environment (e.g., temperature, pH).
- Essential for biological processes, including enzyme function.
Metabolism:
- The set of chemical reactions that occur within living organisms.
- Includes energy capture and usage (e.g., photosynthesis in plants, cellular respiration in animals).
Reproduction:
- The ability to produce new individuals.
- Can be simple (e.g., bacterial fission) or complex (e.g., sexual reproduction in animals).
Growth and Development:
- Organisms grow and develop based on genetic instructions encoded in their DNA.
Response to Stimuli:
- Living organisms respond to internal (e.g., hunger) and external (e.g., danger) stimuli.
- Examples include movement towards light in plants.
Evolution:
- Life is characterized by the capacity for evolution through mechanisms like natural selection.
- Changes in gene frequencies over time can lead to adaptations.

Additional Notes

The video acknowledges that definitions and classifications can evolve as new discoveries are made. It mentions that certain entities, like viruses, challenge traditional definitions of life as they possess some characteristics but not all. The potential for extraterrestrial life and its characteristics is also briefly considered.