Origin of Carbon Compounds
Conditions on early Earth and the origin of carbon compounds
- The conditions on early Earth were not able to support life, but are believed to have been instrumental in the origin of biological compounds that made life possible
- Higher atmospheric temperatures
- The early atmosphere contained higher levels of carbon dioxide and methane than our present atmosphere
- Methane and carbon dioxide are powerful greenhouse gases
- They trap infrared radiation coming from the surface of the earth and prevent it from escaping into space, which in turn increases surface temperatures; this is called the greenhouse effect
- The higher levels of carbon dioxide and methane in the early atmosphere led to the surface temperatures of Earth being much higher than it is today
- The early atmosphere contained higher levels of carbon dioxide and methane than our present atmosphere
- UV radiation
- The atmosphere of early Earth lacked free oxygen, which wasn't only a problem for sustaining life but also prevented ozone from forming
- Ozone (O3) is formed when ultraviolet (UV) radiation from the sun interacts with oxygen molecules (O2)
- Ozone absorbs damaging UV radiation and protects life on Earth
- This lack of free oxygen, and therefore ozone, in the early atmosphere, led to UV radiation penetrating to the surface of Earth
- UV radiation cause DNA damage and increases the rate at which mutations occur; this can be harmful to living organisms
- The atmosphere of early Earth lacked free oxygen, which wasn't only a problem for sustaining life but also prevented ozone from forming
- These conditions on early Earth may have resulted in the spontaneous formation of carbon compounds by chemical processes that do not currently occur
- Adding energy, such as heat or UV radiation, to the mixture of gases that would have been present in the early atmosphere could have led to the formation of organic molecules such as amino acids, simple sugars, nucleotides and fatty acids
- These organic molecules would have formed the building blocks of early cells
- The scientists Alexander Oparin and JBS Haldane both proposed this idea as the 'primordial soup' hypothesis to explain the origin of biological molecules
- It is possible that the high levels of UV radiation on early Earth could then have catalysed the formation of larger polymers, such as proteins, complex sugars, mRNA and phospholipids, from these simpler molecules
The possible formation of the first organic molecules diagram
Heat and radiation could allow the synthesis of inorganic molecules into simple organic molecules which could then have assembled into polymers to provide the building blocks of life