Unit 8 Evolution

Carbohydrates – monosaccharides – Energy! Review Organic Molecules contain carbon Carbohydrates – monosaccharides – Energy! Proteins – amino acids – enzymes, structure, transport, regulate Lipids – fatty acids – Energy storage/insulation Nucleic acids – nucleotides – store/transmit heredity info

Prokaryotic cells (bacteria) – no true nucleus; simple cells Review Prokaryotic Cells vs. Eukaryotic Cells Prokaryotic cells (bacteria) – no true nucleus; simple cells Eukaryotic cells – have nucleus; contain organelles; complex

Spontaneous Generation or Abiogenesis Review Spontaneous Generation or Abiogenesis Before the invention of the microscope, it was a commonly held belief that life could come from nonliving things (matter). “Vital forces” could bring about living things from nonliving material. Maggots arose from meat Mice arose from bags of grain Beetle arose from dung

Experiments to disprove abiogenesis Review Experiments to disprove abiogenesis 1660’s – Francesco Redi Set up jars of meat: One set left open One set tightly sealed One set covered with gauze

Review After several days Maggots appeared on jars left open but were absent from sealed and covered jars

Experiments to disprove abiogenesis Review Experiments to disprove abiogenesis 1800’s - Louis Pasteur – Designed a special curved-neck flask to finally disprove spontaneous generation.

Experiments to disprove abiogenesis Review Experiments to disprove abiogenesis #1 Boiled broth in curved-neck flask. Broth remains free of microorganisms for a year. #2 Curved-neck is broken off Broth becomes cloudy with microorganisms within 2 days. This experiment finally disproved abiogenesis

BIOGENESIS – LIFE CAN ONLY COME FROM OTHER LIVING THINGS CURRENT THEORY – ALL CELLS COME FROM PRE-EXISTING CELLS. LIFE CANNOT SPONTANEOUSLY GENERATE!

Temperature- Very hot, no water initially Earth’s Early History 4.6 billion years ago (bya) Temperature- Very hot, no water initially Very volatile gases in the atmosphere. (CO2, CO, Hydrogen cyanide, Nitrogen, Hydrogen sulfide) NO OXYGEN IN ATMOSPHERE!

How did life arise? 1924 – Aleksandr Oparin hypothesized that organic compounds can be produced from inorganic early atmosphere with electricity (lightning)

How did life arise? 1950’s – American scientists Miller and Urey tried to recreate the atmosphere of the earth in a lab setting

Miller and Urey Set up experiment with boiling water and gases (methane, ammonia, hydrogen gas) Sparked with electricity to simulate lightning and sun’s energy on early Earth. Cooled mixture to cause condensation. Results: After a few days, they obtained amino acids!

Evolution of Organisms on Earth First cells did not use Oxygen, but could not make their own food. So they were Anaerobic Heterotrophic Prokaryotics (bacteria, did not use oxygen) Autotrophic Prokaryotes eventually evolved which produced Oxygen (bacteria, photosynthetic) Eventually, Aerobic Eukaryotic Cells arose (cells with nucleus, used oxygen)

ENDOSYMBIOTIC THEORY Endosymbiotic Theory says that eukaryotic cells arose from communities of prokaryotic cells living together. Symbiosis = relationship (Endo=into)

Endosymbiosis Ancient prokaryotes may have entered primitive eukaryotic cells and remained there as organelles. Mitochondria and chloroplasts share many features of prokaryotic cells.