Chapter 1.5 Evolutionary Foundations

• Changes in the hereditary instructions allow evolution.
• A mutation changes in the nucleotide sequence of DNA.
• Mutations changes the instructions for a cellular component.
• Mutations can be beneficial.
• The wild type is the unmutated cells.
• Biomolecules first arose by chemical evolution.
• Miller and Urey experiments found that biomolecules may have been produced near hypothermal vents at the bottom of the sea or by the action of lightning and high temperature on gaseous mixtures.
• Ribonucleic acid, RNA, can act as a catalyst in biologically significant reactions.
• RNA likely played a crucial role in prebiotic evolution, both as a catalyst and as an information repository.
• RNA or related precursors may have been the first genes and catalysts.
• Simple metabolic pathways may have evolved first, perhaps at the hot vents in the ocean floor.
• In the Miller and Urey experiments, the starting gaseous mixture included NH3, CH4, H2O, H2S, and H2.
• The first step in the evolution of the modern genome was likely the prebiotic formation of simple compounds, like nucleotides, from components of Earth's primitive atmosphere or gases in undersea volcanic vents.
• The second step in the evolution of the modern genome was the production of short RNA molecules with random sequences.
• In the third step of the evolution of the modern genome was selective replication of self duplicating catalytic RNA segments.
• In the forth step of the evolution of the modern genome, there was the synthesis of specific peptides, catalyzed by RNA.
• In the fifth step of the evolution of the modern genome, there was an increasing role of peptides in RNA replication, leading to the coevolution of RNA and protein.
• In the sixth step of the evolution of the modern genome, the primitive translation system developed, with RNA genomes and RNA protein catalysts.
• In the sixth step of the evolution of the modern genome, genomic RNA begins to be copied into DNA.
• In the seventh step of the evolution of the modern genome, the DNA genome formed, translated on RNA protein complexes with RNA and protein catalysts.
• Biological evolution began more than three and a half billion years ago.
• Lipid vesicles containing organic compounds and self replicating RNA gave rise to protocells.
• Protocells with the greatest capacity for self replication became more numerous.
• The first cells probably obtained energy from inorganic fuels, such as ferrous sulfide and ferrous carbonate.
• Photosynthetic processes arose from evolution where pigments captured light energy from the sun and reduced CO2 to organic compounds.
• With the rise of oxygen producing photosynthetic bacteria, the atmosphere became richer in oxygen.
• The three major changes the led to the evolution of eukaryotes were the evolution of the chromosome, the evolution of the nucleus, and the formation of endosymbiotic associations between early eukaryotic cells and aerobic or photosynthetic bacteria.
• In multicellular organisms, differentiated cell types specialize in functions essential to the organism's survival.
• Eukaryotic cells apparently obtained their mitochondria via a symbiotic relationship with ancient bacterium.
• Homologs are proteins encoded by genes that share ready detectable sequence similarities.
• Gene or protein sequence similarities between organisms can determine phylogenetic relationships.
• Genes can be grouped according to the specific process in which they function.
• We can approximate the proportion of the genome dedicated to a specific process.
• Genes involved in regulation of cellular processes tend to increase with organism complexity.
• Housekeeping genes are expressed under all conditions and are not subject to much regulation.
• Large scale sequencing studies have identified many genes in which mutations correlate with a medical condition.
• The proteins genes encode might become the target for drugs to treat a given condition.