Biology: the science of life What is life? Freaky sea-vent worms

Growth and replication aluminum potassium sulfate crystallization What’s missing? nucleation = replication ? prions? computer algorithms

Evolution Three keys: reproduction, variation, selection Improved replicator Improved replicator Neutral variant replicator Life: Reproduction + evolution

Encapsulation and individuality Reproduction Energy and material processing (metabolism) Information storage Environmental response Implementing life (physics + chemistry)

Life elsewhere? Liquid solvent (water) Mars, Europa, Titan (methane and ethane)

Our one data point: Life on Earth

Common descent You are here Genetic and morphological evidence are consistent with all life on Earth sharing common ancestry

History of life on Earth Microscopic life dominates the history of Earth. Humans arose very recently (roughly 200,000 years ago). Do this as in-class exercise

Scales in biology

Tobacco mosaic virus 3x10 -7 m in length, 1.8x10 -8 m in width ~7x kg in mass ~6.4x10 3 bases in genome (single-strand RNA) Have them adding scales

Escherichia coli prokaryotic: no cell nucleus ~3x10 -6 m in length ~7x kg in mass ~5x10 6 base pairs in genome

Saccharomyces cerevisiae eukaryotic: cell nucleus ~5x10 -6 m in diameter ~6x kg in mass ~5x10 6 base pairs in genome

Arabidopsis thaliana multi-cellular plant ~0.2 m in height ~1.2x10 8 base pairs in genome

Drosophila melanogaster multi-cellular insect ~3x10 -7 kg in mass (dry) ~1.2x10 8 base pairs in genome

Mus musculus multi-cellular ~3.5x10 -2 kg in mass ~3.4x10 9 base pairs in genome

HeLa cell human immortal cell line ~25x10 -6 m in diameter ~3.1x10 9 base pairs in genome

Exercise: How many cells in your body? Exercise: How many bacterial cells in your gut?

Homework How far apart are proteins in E coli? How long (physically) is the human genome? How does that compare to the size of a typical cell?

Darwin: First Notebook on Transmutation of Species (1837)