Origin of LifeUrey Miller Experiment

Melissa Wong BIO524: Evolution

Summer 2016

Objectives Students will be able to:

Understand what led to the Urey Miller Experiment Recall what the Urey Miller Experiment was and its

contribution to theories regarding the Origin of Life Recognize the different components that make up the Urey

Miller Apparatus. Reinforce this by using a simulation. Identify the drawbacks and limitations of the experiment Compare and relate Urey Miller experiment to Volcanic

Spark Discharge Experiment Analyze primary research that applies Urey Miller

Experiment to understand abiogenesis. Integrate knowledge of evolution into teaching application

Overview Introduction

Oparin-Haldane Theory

Break #1 for Questions

Urey-Miller Experiment

Experimental procedure and Simulation

Findings and Significance

Limitations

Volcanic Spark Discharge Experiment

Break#2 for Questions

Primary Research and Break #3 for Questions

Teaching Application

Introduction In 1924, Russian biochemist, Alexander

Oparin hypothesized that organic compounds undergo a series of reactions to create more complex molecules. Known as ‘coacervates,’ these complex molecules were capable of absorption and assimilation of organic compounds in the environment. Eventually this would lead to the first life forms. Created the term ‘primordial soup’

In 1929, British scientist, J.B.S. Haldane proposed that the primordial sea served as a vast chemical laboratory powered by solar energy. The sea was equivalent to a hot dilute soup filled with organic monomers and polymers

Got Soup?

Oparin-Haldane Theory According to their theory, life evolved in

the oceans during a period when the atmosphere was reducing: no free O2 while containing: H2

H2O NH3 (Ammonia) CH4(Methane) CO2 (Carbon Dioxide)

Forces such as lightning and electric discharges such as sun wind, UV light, and meteorites created organic molecules in atmosphere, which rained into the ocean.

Oparin-Haldane Theory• Primordial Soup Theory• Abiogenesis Theory

Break#1 for Questions1. According to the Oparin-

Haldane theory, life evolved in the________, during a period when there was a a lack of free __________.

A. ocean, hydrogen B. ocean, oxygen C. atmosphere, sulfur D. atmosphere, nitrogen E. bubble, all elements did not exist on Earth

Break#1 for Questions (cont.)

2. According to the Oparin-Haldane theory, which of these sources of energy did not contribute to the creation of the primordial soup?a. Lightningb. Sun windc. Meteoritesd. Hydrothermal vents

Urey-Miller Experiment In 1953, the Oparin Haldane hypothesis was tested by

Harold Urey: American Physical Chemist, also known for discovery of deuterium. Believed that the early atmosphere contained large amounts of methane

Stanley Miller: graduate student of Urey. Introduced water, hydrogen, methane, and ammonia

gases in a closed apparatus Subjected mixture to high voltage electric discharge for

a week, while water was simultaneously heated. Products accumulated in a water trap below a water cooled

condenser.

Urey Miller ApparatusTry the Experiment Yourself!

Urey Miller Findings 1-2 days of sparking and heating: pink stain forms on

sides of discharge flask. Water in the trap acquires a yellowish color.

Several days (1-2 weeks): stain turns dark red turbid Trap water changes from yellow dark brown

Primary substances: Carbon monoxide (CO) Nitrogen (N2) Organic molecules: aldehydes and cyanides Amino Acid: Glycine and Alanine: 1-3% of solid residue

Significance of Urey Miller Experiment

The Urey Miller Experiment marked the beginning of a scientific field known as Prebiotic Chemistry The synthesis of critical biochemicals in the absence

of chemicals formed by living systems, possibly what would have occurred before life was present on earth.

Most commonly cited evidence for abiogenesis in science textbooks

Limitations to Urey Miller ExperimentDebate whether the ‘brown soup’ can even support life. The substance is highly toxic for certain organisms

Gaseous COAldehyde and cyanideD-amino acids toxic to biological organisms: only L-amino acids used by cells.

Unsure of the exact composition of Earth’s original atmosphere. Urey-Miller may have missed components or miscalculated the exact % of each substance.

There is evidence of major volcanic eruptions 4 billion years ago, which would have added CO2, nitrogen, hydrogen sulfide, and sulfur dioxide into the atmosphere.

No actual organisms were formed in this experiment

Volcanic Spark Discharge Experiment

Following Miller’s death in 2007, his former student and geochemist, Jeffrey Bada inherited Miller’s lab, including 11 vials from 1953.

Performed the experiment under volcanic eruption conditions. Jet of steam aimed at the spark discharge.

Used modern HPLC (high performance liquid chromatography) and mass spectrometry Samples contained a greater abundance of biologically relevant molecules Contained oxidation products of sulfur containing amino acids: cysteine

and methionine. Methionine initiates synthesis of proteins

22 amino acids, 5 amines, and many hydroxylated molecules produced

Break#2 for Questions3. _______, water, methane, and ammonia were added in the Urey Miller Experiment to simulate early Earth conditions4. The Urey Miller experiment modeled the _______cycle that would have occurred during early Earth conditions A. rock B. nitrogen C. carbon D. water

Break#2 for Questions (cont.)5. List some limitations from the Urey Miller Experiment

6. In 2007, geochemist Jeffrey Bada was able to test 11 samples from the Miller Urey experiment, subject it to volcanic eruption conditions and produce more biologically relevant molecules. What led Bada to do this, that Miller-Urey was not able to in 1953?

Primary Research2015Scientific ReportsFeatured on www.nature/scientificreportsXie et al.

Primordial soup was edible: abiotically produced Miller-Urey mixture supports bacterial growth

Xie et al. Methods:

MU sample was created with Methane (CH4), hydrogen (H2), and ammonia (NH3) gases

GC/MS analysis LC/MS amino acid analysis E. coli adaptation to control media E. coli growth measurements

Bacterial Growth phases• Lag time: very little/no

bacterial growth• Exponential Phase: # cells

doubles at an exponential rate

• Stationary Phase: population growth levels off. Rate of cell death = rate of cell division

• Death Phase: bacteria dies

Decrease in lag time of e.coli growth

 Xie, X., Backman, D., Lebedev, A. T., Artaev, V. B., Jiang, L., Ilag, L. L., & Zubarev, R. A. (2015). Primordial soup was edible: Abiotically produced Miller-Urey mixture supports bacterial growth. Sci. Rep. Scientific Reports, 5, 14338. doi:10.1038/srep14338

Estimating bacterial # by indirect method

Measuring Turbidity using Spectrophotometer

http://classes.midlandstech.edu/carterp/courses/bio225/chap06/Microbial%20Growth%20ss5.htm

Growth curves for e.coli in dried and reconstituted in water MU mixture

 Xie, X., Backman, D., Lebedev, A. T., Artaev, V. B., Jiang, L., Ilag, L. L., & Zubarev, R. A. (2015). Primordial soup was edible: Abiotically produced Miller-Urey mixture supports bacterial growth. Sci. Rep. Scientific Reports, 5, 14338. doi:10.1038/srep14338

Primordial soup was edible: abiotically produced Miller-Urey mixture supports bacterial growth

Conclusion: Study showed that adapted bacteria can

grow on reconstituted MU mixture as the only source of carbon.

Authors conclude that Earth provided a hospitable environment for early life forms, “regardless whether they spontaneously emerged on Earth or have arrived from outer space.”(6)

E.Coli has more sophisticated metabolic machinery than primitive life forms

If Panspermia occurred, Earth being an abundant food source may have been a decisive factor that determined its survival on this planet.

Cueva De Villa Luz, Southern Mexico

Snottites! Where life is thriving! Start: 9:12 End: 12:30

Break#3 for Questions!1. In shortening bacteria’s lag

phase, more/less bacterial growth results

2. _____ type of bacteria was used in the Xie et. al study, which is a modern day organism that may have retained its metabolic functions from primitive forms.

3. Penny Boston and Diana Northup explored caves in Southern Mexico. They found that bacteria thrived in underground caves, feeding off of _______, which also form snottites.

Teaching Application Jonathon Wells and "Icon's of Evolution"

Start video at 2 minutes Alan D. Gishlick’s Response in National Center for Science Education

View full article here We can improve our textbooks with more up-to-date information Teaching Suggestion:

Present this “icon” in a traditional fashion Allow students to denigrate Students will see that just because one experiment is not completely accurate,

we cannot make the assumption that everything else is wrong as well.

Questions?

References  Origin of life experiments revisited.(2016) Available at:

http://www.rsc.org/chemistryworld/News/2011/March/21031102.asp (Accessed: 28 June 2016).

"Origin Of Life: Twentieth Century Landmarks." Origin Of Life: Oparin-Haldane Hypothesis. N.p., n.d. Web. 27 June 2016.

Johnson, A.P., Cleaves, J.H., Dworkin, J.P., Glavin, D.P., Lazcano, A. and Bada, J.L. (2008) ‘The Miller volcanic spark discharge experiment’,Science, 322(5900), p. 404. doi: 10.2307/20145054.

Xie, X., Backman, D., Lebedev, A. T., Artaev, V. B., Jiang, L., Ilag, L. L., & Zubarev, R. A. (2015). Primordial soup was edible: Abiotically produced Miller-Urey mixture supports bacterial growth. Sci. Rep. Scientific Reports, 5, 14338. doi:10.1038/srep14338