How Does Life Begin and Develop?
Objective
1
Sources of 0rganics on Earth
Objective
2
Origin of Life's Cellular Components
Objective
4
Genomic Clues to Evolution
Objective
5
Linking Planetary and Biological Evolution
Does Life Exist Elsewhere in the Universe?
Objective
7
The Extremes of Life
Objective
8
Past and Present Life on Mars
Objective
9
Life's Precursors and Habitats in the Outer Solar System
Objective
10
Natural Migration of Life
Objective
11
Origin of Habitable Planets
Objective
12
Effects of Climate and Geology on Habitability
Objective
13
Extrasolar Biomarkers
What is Life's Future on Earth
and Beyond?
Objective
14
Ecosystem Response to Rapid Environmental Change
Objective
15
Earth's Future Habitability
Objective
16
Bringing Life with Us beyond Earth
Objective
17
Planetary Protection
Question: How Does Life Begin and Develop?
Origin of Life's Cellular Components
Objective 2: Develop and test plausible pathways by which ancient counterparts of membrane systems, proteins and nucleic acids were synthesized from simpler precursors and assembled into protocells.
For living systems to emerge from abiotic matter, organic constituents on the prebiotic Earth must have self-organized and acquired the capabilities needed to survive and reproduce, thus forming the earliest precursors of life. Eventually, the biomolecules of life became enclosed within a lipid membrane, forming rudimentary assemblages that resembled cells as we know them, or protocells. Among the essential protocellular functions were the acquisition and transduction of energy from the environment, and catalysis to support the synthesis of cellular components (metabolism) and information transfer to succeeding generations (genetics). To explain the origin of life on Earth, it is necessary to demonstrate that essential functions can be accomplished utilizing only the molecules that may have been available in the protobiological milieu. In contemporary life, all these functions are performed by complex systems of proteins, nucleic acids, and membrane-forming material. The early systems must have been much simpler.
Implementation
Near to mid-term:
- Conduct ground-based laboratory
research on chemical pathways leading to the emergence of the macromolecules
of life. These pathways should be consistent with the thermodynamic
and environmental constraints on the early earth.
- Develop models of primitive bioenergetics, replication, and catalysis of the reactions in metabolic pathways which can be linked via plausible, continuous paths to the same functions in modern organisms on earth.
Future extensions:
- Combined with studies on the chemistry and environmental conditions on the prebiotic earth and with the analysis of metabolic evolution of microorganisms, this work will ultimately lead to the reconstruction of protobiological evolution from a collection of organic molecules to the earliest, unicellular organisms.