Biogenesis and Origin of Life Chapter 14 -1 Pg. 279-281 and 284-290

Where did these mice come from?

Origin of Life Biogenesis: life comes from other living organisms Spontaneous generation: early theory that life comes from non-living organisms

Evidence Against Spontaneous Generation Redi’s experiment Indicated that maggots didn’t come from rotting meat because flies couldn’t land

Evidence Against Vital Force Early Idea Vital force: Something in the air that gave rise to life Spallanzani’s experiment: Disproved that organisms came from “vital force” by preventing air contact

Evidence Against Vital Force Pasteur’s experiment: Showed that micro-organisms in the air contaminated the flasks disproving “vital force”

First Life Forms/First organic compounds Spontaneous Origin: the process of life developing from non-living chemical interactions Ex. “Primordial Soup”

Evidence Supporting Spontaneous Origin Oparin: (1920) Hypothesized that primitive Earth’s atmosphere was NH3, H2, H2O, and CH4 [No Oxygen] Miller-Urey: (1953) Produced organic compounds based on the hypothesized composition

Primordial Soup: Water Water has a positive (+) and a negative (-) pole This makes it polar Polar substances like water will dissolve other polar substance Like dissolves like Pulls apart ionic molecules like NaCl

Water bonding Hydrogen bonds: bonds BETWEEN water molecules (the hydrogen from one water molecule bonds with the oxygen from another water molecule)

Molecules to cell-like structures Non-polar molecules start to group up to avoid water Leading to cell-like structures beginning to form Coacervates: Droplets that are made of different macromolecules Microspheres: small spheres that are made of many protein molecules organized into a membrane Coacervates can grow, microspheres can bud: show that some aspects of cellular life can arise without direction from genes

First Life Forms Role of RNA Amino acids linked to make a chain that could make shapes like ribozymes (early ribosome) which could replicate itself

First Life Forms - The First Cells Prokaryotes before eukaryotes 3 major trends all interrelated: Anaerobic  Aerobic Heterotrophic  Autotrophic Chemosynthetic  Photosynthetic

The First Eukaryotes Endosymbiosis Theory Supporting evidence: Mitochondria (aerobic prokaryote) and chloroplasts (photosynthetic prokaryote) are thought to be prokaryotic cells that were engulfed by a bigger prokaryote Created mutually beneficial relationship Safer environment in exchange for energy source Supporting evidence: They have their own DNA DNA is circular like other prokaryotes Replicate on their own

Sequence of First Cells Anaerobic Heterotrophic Prokaryotes Chemosynthetic Prokaryotes Photosynthetic Prokaryotes Endosymbiosis Occurs Here! Aerobic Eukaryotes Photosynthetic Eukaryotes