Origin of Life

Redi’s Experiment Challenged the idea of spontaneous generation –(SP: belief that life came from nonliving things) –proved that flies laid the eggs that caused other flies

SPALLANZANI’S EXPERIMENT hypothesized that microorganisms formed from other microorganisms. (not from SP) boiled broth became contaminated only when microorganisms from the air entered the flask.

Pasteur’s Experiment Placed broth in flasks w/ curved neck T0 prevented microorganisms, from entering Broth boiled inside remained clear for up to a year. When the curved necks was broken off, the broth became contaminated w/ microorganisms Settled the debate: spontaneous generation did not occur

Topic: Biogenesis #1 Date: What is spontaneous generation? 2. Who was the first to question spontaneous generation? 3. Describe his experiment. 4. Who finally disproved spontaneous generation?

History of Life…theory Cells may evolve and change, but new cells always arise from existing cells. How, then, did the first cells originate? scientists attempt to reconstruct the processes that gave rise to the first cellular life.

Earths Age: 4.6 billion years old Was made from studying layers of sediment in Earth’s crust. Radioactive dating is also used to determine the age of Earth

RADIOACTIVE DECAY Can date objects Ex. Ages of fossils and rocks can be determined by measuring the amount of radioactive decay that has occurred

1 st organic compounds Oparin: early atmosphere consisted of: NH 3, H 2 ; H 2 O, and compounds made of hydrogen and carbon, such as methane, CH 4. Energy from lightening caused a rxn to form early proteins

Miller and Urey’s Apparatus Miller and Urey’s Tested Oparin’s theory Used apparatus containing similar chemical makeup of the atmosphere Added electricity Organic compounds formed: Nucleic acids, ATP, amino acids

Cell Like Structures Under early Earth conditions, membrane- bound structures have been formed in the laboratory these structures may have replicated molecules of RNA Believed to be the 1 st cells

First Prokaryotes Because there was no O 2, the 1 st organisms were: – Anaerobic –Prokaryotes –Heterotrophs

The 1 st Autotrophs Chemosynthesis: Ex. Archaebacteria Live in harsh conditions Use CO 2 for food

1 st Eukaryotes Through endosymbiosis (mutually beneficial relationship) small prokaryotes fused w/ lger prokaryotes Believed to be the 1 st organelles such as mitochondria and chloroplasts The “organelles” carried out aerobic respiration and contained DNA

Topic: Biogenesis #2 1. How old is Earth believed to be? 2. Explain the difference b/w radioactive and Carbon dating. 3. Who was the first to create organic compounds from inorganic compounds? 4. What is endosymbiosis?