Letcture 1: The Scope of "Life"
In he 1920s, Alexander Oparin and J.B.S. Haldane suggested that Earth's early atmosphere had little _________ ---that it was composed primarily of _____________,____________,_____________ and _________ _________.
1. Oxygen 2. Hydrogen, Methane, Ammonia, and Water Vapor.
Two Books H.G. Wells wrote
1. The Science of Life 2. The Outline of History
Experiment which demonstrated that its possible to synthesize many organic compounds under conditions simulating those thought to have prevailed on the early Earth. (Spontaneous Generation of organic compounds)
Classic Experiment by Stanley Miller (1953)
According to the primordial soup theory AND the Miller-Urey experiment, which gases were believed to have been a major component of the primitive atmosphere?
Methane, Hydrogen, Ammonia & Water Vapor
Panspermia Hypothesis
The original life on Earth arrived here from another planet.
Why did H.G. Wells write the "Science of Life?"
Wells intended this book to be read by ordinary busy people.
The Science of Life (1929)
Written by H.G. WELLS (1866-1946) with collab with biologist, Julian S. Huxley & son (G.P. Wells)
Which of the following is a key assumption of the primordial soup theory? A. Sunlight provided the energy needed to convert inorganic compounds to organic compounds. B. The composition of the primitive atmosphere was different than that of the current atmosphere. C. Amino acids can be produced from inorganic compounds in the laboratory. D. Organic compounds can only be produced by the reaction of other organic compounds.
(B) The primordial soup theory assumes that the compositions of the primitive and current atmospheres vary widely. This assumption led to the development of the Miller-Urey experiment, which produced various organic molecules from the compounds thought to be most abundant in the primitive atmosphere. The current atmosphere is composed mostly of nitrogen and oxygen.
Which of the following is not an organic molecule? A. Carbohydrates B. Water C. Lipids D. Nucleic Acids
(B) WATER: Organic molecules are found only in the bodies or products of living organisms. Carbohydrates, lipids, proteins, and nucleic acids are all produced by living organisms. Although living organisms are composed largely of water, WATER IS INORGANIC because it is not produced by living organisms.
Which of the following statements would scientists supporting either theory (Primordial Soup/Hydrothermal Vents theorys)most likely agree on? A. At least some organic compounds on Earth likely originated in meteorites from space. B. The production of amino acids requires the existence of a temperature gradient. C. The existence of water on Earth was essential to the original formation of organic compounds. D. A single method most likely produced the original versions of all organic molecules.
(C) Both theories identify WATER as playing an integral role in the development of organic compounds on Earth. The primordial soup theory identifies water as one of the four major components of the primitive atmosphere. The hydrothermal vents theory identifies deep ocean water as the site of organic compound formation.
Both theories on the origin of organic molecules are based on the assumption that those molecules: A. contain different atoms than inorganic molecules. B. only exist in the atmosphere and deep ocean. C. have not yet been produced in the laboratory. D. can be produced from inorganic molecules.
(D) CAN BE PRODUCED FROM INORGANIC MOLECULES: Both the primordial soup theory and the hydrothermal vents theory assume that organic molecules can be produced by reactions that cause the rearrangement of atoms in certain inorganic molecules. Scientists believe this to be an important step toward the existence of life on the earth.
4 Classes of Organic Compounds
1. Amino Acids - building blocks of protiens 2. Nucleic Acids - Includes DNA & RNA 3. Carbohydrates - Includes sugar, starch, & cellulose (wood fiber) 4. Libids: Includes Fats & Hormones
The specific source of energy used to form simple organic molecules is:
A MAJOR DIFFERENCE BETWEEN THE 2 THEORIES: The two theories disagree on the energy source used to fuel the reactions that originally produced organic compounds. The primordial soup theory identifies atmospheric lightning as the energy source, whereas the hydrothermal vents theory argues that the energy came from within the earth.
Organic Chemistry
A chemistry based on organic compounds (chemical compounds built around CARBON)
Stanley Miller, under the guidance of Professor Harold Urey, set up the Miller-Urey Experiment to test this hypothesis.
He included basic chemicals that were present on Earth before life began: water, methane, ammonia, and hydrogen. These molecules contain the most abundant elements in living cells, which are carbon, hydrogen, oxygen, and nitrogen. Miller connected two sterile, glass flasks by a series of glass tubes. One flask contained water and the dissolved molecules. This flask was heated, and the water vapor and gases released into the tubing. They could freely move into the second flask, which was sparked by electrodes to simulate lightning strikes. The gases were then condensed into a liquid that was carried back to the original flask. The cycle went on continuously for two weeks. Within one day the solution in the flask had developed a pinkish hue. By the end of the experiment, Miller and Urey identified many new compounds that formed in the apparatus. These included several different types of amino acids, the small molecules that make up proteins, as well as simple carbohydrates.
The hydrothermal vents theory states that organic molecules originally formed:
IN THE DEEP OCEAN... The hydrothermal vents theory identifies the location of organic molecule formation as the deep ocean. Hot gases and energy from inside the earth enter the deep ocean through hydrothermal vents. The theory suggests that organic molecules are then produced within the temperature gradient generated at hydrothermal vents.
Ammonia (NH3) is an:
Inorganic compound. (IC) According to the passage, ammonia was believed to be a major inorganic component of the primitive atmosphere that contributed to the production of organic molecules.
The most fundamental, most essential propertyof life is dependent on ___________ ____________.
Organic Chemistry
Today, why is it impossible for "Sponaneous Generation of Organic Compounds" to happen/take place?
Organic Compounds (OC) are too fragile... TODAY, our planet is made of mostly nitrogen and OXYGEN. Oxygen "Breaks-Down/Oxidizes" - (pulls electrons out of OC(s) and turns them into Inorganic Compounds (IC).)
In the Miller-Urey Experiment; The purpose of the heat source is to:
Produce water vapor for the simulated atmosphere... heat source is located underneath the small sphere that simulates the water in the earth's oceans. According to the diagram, the ocean (small sphere) supplies water vapor for the reactions in the atmosphere (large sphere). The heat source facilitates the production of water vapor.
J. B. S. Haldane (1892-1964) Alexandr Oparin (1894-1980)
Suggested, that early earth did NOT have much/any Oxygen or an Oxidizing Atmosphere. The first atmosphere of earth was composed of (Hydrogen, Methane, Ammonia, & Water Vapor)
The reaction that produces organic molecules occurs in which part of the Miller-Urey apparatus?
THE LARGE SPHERE: The small sphere simulates the ocean, which provides water vapor for the primitive atmosphere. The actual reaction that produces organic molecules occurs as the electrical current is passed through the large sphere that simulates the primitive atmosphere. The condenser then cools the gases in the atmosphere, allowing newly produced organic molecules to condense into solution and travel to the trap for sampling.
The greatest limitation in the design of the Miller-Urey experiment is the:
The "PRESENCE OF A CONSTANT ELECTRICAL CHARGE" is a potential limitation of the Miller-Urey apparatus. ...Because it causes experimental conditions to differ from the conditions scientists believe actually existed in the primitive atmosphere. The constant charge simulates a constant supply of lightning that scientists do not believe existed.
Scientists consider the outcome of the Miller-Urey experiment to be evidence:
The Miller-Urey experiment supports the primordial soup theory: ... because it successfully produced organic compounds under the same conditions as scientists believed existed on primitive Earth. The experiment was specifically designed to investigate this theory and does not provide direct evidence to support or reject the hydrothermal vents theory.
