BIOLOGY 1A03 Chapter Notes - Chapter 2: Chemical Evolution, Hydrogen Bond, Electron Shell

• School: McMaster University
• Department: Biology
• Course: BIOLOGY 1A03
• Professor: Lovaye Kajiura

Document Summary

Biology chapter 2: water and carbon: the chemical basis of life. Proposition that in early earth, simple compounds in the atmosphere and ocean combined to form larger, more complex substances. Process responsible for this pattern was the conversion of kinetic energy in sunlight and heat to chemical energy in the form of bonds between atoms that formed large, complex compounds. Hypothesis was that one complex compound was able to self-replicate and as it multiplied, chemical evolution became biological evolution. Eventually a self-replicating molecule became surrounded by a membrane. Chemical evolution got under way because: abundant sources of outside energy were available to trigger endergonic reactions, some of these molecules produced by chemical evolution are found in organisms living today. An atom is most stable when its valence shell is filled. One way that shells can be filled is through the formation of chemical bonds. Asymmetric sharing of electrons results in polar covalent bonds (dependent on electronegativity)