Properties and Origin of Life

Summary:

In this Properties and Origin of Life note, it is explained that life is difficult to define, but living organisms share common properties. They are highly organized and adapt to their environment through natural selection. Organisms regulate their internal environment, reproduce, grow, develop, and have metabolism. All modern organisms are composed of cells. The origin of life remains uncertain but involves key developments like an abiotic synthesis of organic molecules, polymerization, self-replicating molecules, and protocells. The first true cells were likely unicellular prokaryotes, and eukaryotes evolved through endosymbiosis.

Excerpt:

Properties and Origin of Life

Life defies a simple, one-sentence definition. In fact, the question “What is life” is probably the hardest
question to answer. Distinguishing a living thing from a non-living thing is a much easier task. Even a
child knows that a piece of rock is not alive while a cat is. This is because even though we do not
know exactly what life is, we know the properties that separate a living thing from a non-living thing.

Organization

Biological systems are extremely organized. At the chemical level, atoms are organized into biomolecules which in turn comprise cellular organelles. Organelles function interrelatedly and give rise to cells, the basic unit of life. In complex multicellular organisms, cells are organized into tissues, tissues form different organs, and organs are components of organ systems that comprise an organism. The biological organization goes well beyond the organismal level. Organisms of the same species make up a population, a collection of populations of different species form a community, biological communities, together with the abiotic components of the environment, forms an ecosystem, and the collection of all ecosystem forms our planet’s biosphere.

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Evolutionary Adaptation
Organisms are extremely adapted to their environment. These adaptations are a result of natural selection. Members of a species with characteristics that are better suited to the environment leave more offspring. This ensures that over time, the population becomes more and more adapted to its environment.