The Cell: Nature's First Life-form (New Biology), Revised by Joseph Panno
By Joseph Panno
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The first component in the chain captures the stored electrons by separating NADH into NAD and H+ (not shown). The electrons travel through the chain powering a pumping function of each component resulting in a proton (H+) concentration gradient across the inner membrane and are eventually transferred to oxygen (O2) leading to the production of water. The protons, moving down their concentration gradient, power the synthesis of ATP by the synthetase. The only exhaust from this power plant is water, that the cell uses, and CO2, a gas that is exhaled by the lungs.
Thus, RNA replication would have proceeded much more quickly, producing a larger, more diverse population of molecules. Life Began in an RNA World The molecule that led to the first living cell would have to be able to replicate itself as well as function as an enzyme. DNA fulfills the first condition but it has no known enzymatic activity, and, at the time of the Urey-Miller experiment, this was thought to be the case for RNA as well. Both were believed to be incapable of regulating chemical reactions, so that neither could build protein molecules by themselves.
Protein is made from amino acids linked together to form a long chain that can fold up into a three-dimensional structure. RNA and DNA are long chains of nucleotides. RNA is generally single stranded but can form localized double-stranded regions. DNA is a double-stranded helix, with one strand coiling around the other. A phospholipid is composed of a hydrophilic head-group, a phosphate, a glycerol molecule, and two hydrophobic fatty acid tails. Polysaccharides are sugar polymers. 12 The Cell Â� carboxyl end of one amino acid to the amino end of a second amino acid.