BIOL 112 Lecture 13

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Genetic Model Organisms

Observation: mutations of hox genes result in new forms:

Example:

• Mouse
• Drosophila
• C. elegans (nematode)
• Zebrafish

Chordates

All chordates have a notochord anh spinal cords

Subgroupings of chordates:

	Extant Example
invertebrates	lancelets
jawless vertebrates (have vertebra)	lamrey
jaw vertebrates (have vertebra)	bony fish

Chapters 25 & 27: Origins of [Early] Life and Prokaryotes

• Earth formed 4.6 bya
• Life started 3.9 bya

Early Atmosphere:

• No O₂
• Lots of H+
• Sulphur
• Water vapor

Criteria for life: Replicate and Metabolize

• originally abiotic environment.
• abiotic synthesis of organic building blocks for life (amino acids and nucleotides)
• chaining of basic amino acids and nucleotides into polymers

Oparin's and Haldane's Hypothesis

N₂, N oxides, CO₂ CH₄, NH₄, H₂, H₂S + {lightning, energy}

This recipe somehow resulted in "primitive soup" of amino and nucleic acids

Amino acids accounted for (confirmed by Miller and Urey's experiment), but no nucleotides

How and where to make polymers from building blocks without enzymes?

• alkaline (basic) thermal vents: warm, long-lived environments with catalytic material (FeS) and ATP analogs. pH gradient emulated electron transport.