CHAPTER 1 – ORGANIZATION, WHAT IS LIFE?
7 Attributes of Life:
Order and Organization (Cell Theory)
Energy Processing; i.e., metabolism (at least sometimes; but think about
spores, seeds, hibernation, and diapause)
Response to the environment (Sensitivity)
Regulation (e.g. Feedback Inhibition, Positive feedback)
Growth and development
Evolution (can mutate = population response)
- Life is not restricted to forms that are actively metabolizing.
- Bacterial Spore
- Zero metabolism
- Remain “viable” for 1000’s of years
- Dormant seeds
- Need germinants
- Many plants and animals arrest metabolism temporarily
- Something is
when it has a low metabolic rate and a suspension of growth and
- Living forms don’t have to be independent (autonomous). Think parasite (Bdellovibrio).
- A virus is not considered to be alive by some scientists because it is not a cell.
Chemical Requirements of Life:
Also Oxygen, Nitrogen, Hydrogen, Sulfur, Phosphorus (
Phosphorous). Also trace elements: Mn, Mg, Na, K, Cl, Fe, etc.
Nucleic Acids. DNA is found in all cellular life forms. RNA is probably the
first genetic material and is found in some viruses.
All life forms must have metabolic pathways.
Laws of Thermodynamics:
Energy cannot be created or destroyed; it can only change forms.
Energy goes from ordered to disordered (entropy never decreases) in a closed
Laws of Biology:
The Biosphere is not a closed system
Living forms are composed of chemicals, nothing else: C, O, N, H, S, P, +
trace elements forming Nucleic Acids, Proteins, Carbohydrates, and Lipids.
These functions give rise to “emergent properties” as they are organized into
more complex systems: Metabolism, Regulation, Growth, Development, and
Living forms go from lower order to higher order; i.e., become organized (so,
they “disobey” the 2
Law of Thermodynamics)