Chapter 11

Last Universal Common Ancestor

not extinct (still alive)

point in history in which phylogenic analysis cannot possibly see [LUCA represents a phylogenetic event horizon]

RNA is the basis of life

pool of molecules that existed in liquid form before life arose—developed over time, grown more diverse via matter arriving on extraterrestrial objects known to carry amino acids, purines, and pyrimidines--energy from lightning, volcano, internal heat, cosmic rays

simulation of the "prebiotic soup hypothesis"--found that amino acids (the building blocks of life) formed

Tested RNA for heritability and observed natural selection acting on the mutations

RNA enzymes (not proteins--less stable and efficient than proteins)

beneficial interaction between two species that increases fitness

two or more molecular substrates combine in a positive way to replication--important for replicators

rate of replication of one replicator is dependent on the concentration of the preceding replicator--relies on molecular mutualism [i.e. A --> B --> C --> D --> A]

species interaction in which only one party benefits, and the other suffers negative consequences

primitive cell (membrane)

• increases concentration of replicators
• control microenvironment inside the cell
• creating chemical gradients across membrane
• cell membrane as defense mechanism
• partitioning various functions

technique for systematically disrupting gene function

• energy metabolism
• regulatory function
• fatty acid/lipid metabolism
• synthesis of nucleotides
• transcription
• DNA metabolism
• protein binding

• Genes that are critical for proper function
• 16: assoc w/ gene metabolism
• 106: linked to RNA metabolism
• 15: processing/folding proteins
• 56: energetic/intermediate metabolism
• 13: other cellular processes