Iron Sulfide Bubbles Hypothesis Statement

Presentation on theme: "Chapter 12, Section 3 And parts of 12.4"— Presentation transcript:

1 Chapter 12, Section 3 And parts of 12.4
Origins of LifeChapter 12, Section 3And parts of 12.4

2 Early TheoriesSpontaneous generation = the idea that living things could come from nonliving thingsThree experiments disproved this theory:Francesco Redi (1665)Lazzaro Spallanzani (1767)Louis Pasteur (1862)

3 Redi’s Experiment People thought maggots came from meat
Redi showed that maggots came from flies laying eggs on the meat

4 Spallanzani’s Experiment
People still thought that microorganisms could spontaneously generateSpallanzani boiled two flasks of broth, then left one open and sealed oneBacteria grew in the open flaskThe sealed flask remained sterilePeople convinced that spontaneous generation exists said that boiling the broth killed a “vital principle” in the air

5 Pasteur’s Experiment Disproved spontaneous generation once and for all
Microorganisms only grew in the flask when the swan neck was brokenThe swan neck prevented particles in the air from entering the brothAnimation

6 Biogenesis – Life from Life
A possible sequence:Inorganic molecules form and make small organic moleculesSmall organics join to form macromolecules / polymersOrigin of RNA / DNA to make inheritance possiblePackaging within membranes

7 Related VocabularyInorganic – any substance that doesn’t contain both carbon (C) and hydrogen (H)Organic – any substance that contains both C and H; usually comes from something that is, or once was, livingPolymer – substance made up of many repeating subunits (monomers)Macromolecule – large molecules; biological examples include carbohydrates, lipids, proteins, and nucleic acids

8 Early EarthFor the first 700 million years, Earth was most likely very hot and in a molten stateOver time, the materials making up Earth separated into Earth’s layers (crust, mantle, core)Gases released from Earth’s interior formed an atmosphereEarly Life on Earth – 4:37

9 Oparin and Haldane – 1920sTheory for how life may have developed on early Earth; based on assumptions that:There was little or no oxygen presentThe atmosphere was mainly formed from volcanic vapors – methane, ammonia, hydrogen, water vaporFelt it would be possible for inorganic molecules to be converted to organic forms using energy from the sun and lightningAt the time, no effective way to test this

10 Miller and Urey – 1950s Tested Oparin-Haldane hypothesis
Simulated atmosphere containing gases Oparin & Haldane thought were presentExposed gases to electric shocks to simulate lightningProduced small organic compounds – mainly amino acidsAnimation

11 Follow-up to Miller/Urey
Based on the gases emitted from volcanoes today, scientists think the atmosphere would have been different from what Oparin & Haldane proposedMore carbon monoxide (CO), carbon dioxide (CO2), nitrogen gas (N2) and water vaporSimilar experiments using this “updated” representation of the atmosphere produced smaller amounts of amino acids

12 Meteorite HypothesisAnalysis of meteorites indicate that organic molecules can be found in spaceThis suggests the following possibilities:Amino acids may have been present when Earth formedOrganic molecules may have arrived on Earth through meteorite / asteroid impact

13 Formation of the First Cells
Once organic molecules / compounds are formed, how did they get packaged into cells?Iron-sulfide bubbles hypothesisLipid membrane hypothesis

14 Iron-Sulfide BubblesIron sulfide rising from deep sea vents combines with cool ocean water to form chimney-like structures with many compartmentsBiological molecules may have combined inside these compartments, which acted as membranesWith the right combination of ingredients, the first organic cell membranes may have formed

15 Lipid-membrane Hypothesis
Lipids spontaneously form membrane-enclosed spheres called liposomesLiposomes could act as membranes around a variety of organic molecules, separating them from the environment

16 The First Genetic Material
It has been hypothesized that RNA was the genetic material for the earliest life formsCech & Altman (1980s) discovered that RNA can:Catalyze reactionsCopy itself

17 The First EukaryotesFossil evidence indicates that the first living things were prokaryotes (bacteria)First appeared ~3.5 BYAEukaryotes – cells with a nucleus and other organelles – don’t appear in the fossil record until approx. 1.5 BYAHow did the first eukaryotic cells develop?

18 Endosymbiosis Suggested by Lynn Margulis (1970s)
Idea that mitochondria and chloroplasts used to be simple prokaryotic cells that were engulfed by larger prokaryotesAnimation

19 Endosymbiosis, cont’d What evidence supports endosymbiosis?
Both mitochondria and chloroplasts:Have their own DNAHave their own ribosomesCan copy themselvesAre about the same size as prokaryotesHave DNA in the shape of a circle, like bacterial / prokaryotic DNA

How life on Earth developed in the distant past is a prevailing mystery, but we know that electricity was a key piece in the jigsaw puzzle.

One theory is that early lifeforms found some way to channel electricity from the ocean floor using naturally occurring chimney-like structures that develop at hydrothermal vents.

And now scientists have managed to use these chimneys to power a lightbulb in the lab, offering clues as to what gave our earliest ancestor the original spark of life.

Bright sparks: Scientists have managed to use geothermic vents to power a lightbulb in the lab (pictured), offering clues as to how early life may have harvested electricity from the ocean floor

Chimney-like structures, also known as 'chemical gardens', form on the seafloor at hydrothermal vents - openings in the planet's surface where geothermally heated water bubbles out.

It is thought that the structure of these chimneys, made of various porous minerals, can emulate processes critical to life that generate energy and organic compounds.

ALKALINE VENT HYPOTHESIS  

Russell first proposed the alkaline vent hypothesis in 1989, and even predicted the existence of alkaline vent chimneys more than a decade before they were actually discovered.

His theory was that at the time life first formed, the ocean was acidic and contained positively charged protons.

The vents on the ocean floor produced warm alkaline water filled with negatively charged hydroxide ions. 

The structure of the chimneys and the chemistry of the ocean floor created an environment similar to a basic battery. 

And now it looks like the alkaline vents were able to create enough electricity to do something useful. 

Thin membranes within them can establish electrical gradients that cause electrons to jump between them, the basis of electricity.

Scientists from Nasa's Jet Propulsion Laboratory (JPL) in California have grown their own chimneys in the lab to try to simulate this effect. 

And they have managed to use the electricity generated to power a light bulb. 

'These chimneys can act like electrical wires on the seafloor,' said Laurie Barge, lead author of a new paper on the findings. 

'We're harnessing energy as the first life on Earth might have.'

The findings demonstrate that underwater structures may indeed have been the source of electricity for early life. 

While the story of the start of life on Earth is far from complete, the experiment adds weight to the theory that life sprang from warm vents on the ocean floor.

'Life doesn't want to get electrocuted, but needs just the right amount of electricity,' said Michael Russell of JPL, a co-author of the study. 

Scientists from Nasa's Jet Propulsion Laboratory in California have grown their own geothermal vents or 'chimneys' in the lab to try to simulate the environment of the ocean floor when life first formed

'This new experiment confirms what that amount of electricity is - just under a volt.' 

Russell first proposed the alkaline vent hypothesis in 1989, and even predicted the existence of alkaline vent chimneys more than a decade before they were actually discovered.

Chimney-like structures, also known as 'chemical gardens' (pictured), form on the seafloor at hydrothermal vents

His theory was that at the time life first formed, the ocean was acidic and contained positively charged protons.

The vents on the ocean floor produced warm alkaline water filled with negatively charged hydroxide ions. 

The structure of the chimneys and the chemistry of the ocean floor created an environment similar to a basic battery. 

And now it looks like the alkaline vents were able to create enough electricity to do something useful. 

The researchers connected four of the chemical gardens submerged in iron-containing fluids, to turn on one light bulb.

In the study, they made chimneys of iron sulfide and iron hydroxide, geological materials that can conduct electrons.

The scientists hope to reproduce the experiment using different materials that were present in Earth's early oceans to build the chimneys.

'With the right recipe, maybe one chimney alone will be able to light the LED - or instead, we could use that electrochemical energy to power other reactions,' said Barge. 

'We can also start simulating higher temperature and pressures that occur at hydrothermal vents.' 

Experiments could test whether the same processes could have led to life emerging on other planets too.

The electrical requirements for early life is just one small part of the puzzle of how life emerged on Earth, but researchers hope it will help them piece together the full picture. 

The comments below have not been moderated.

The views expressed in the contents above are those of our users and do not necessarily reflect the views of MailOnline.

We are no longer accepting comments on this article.

Share or comment on this article

Comments

Leave a Reply

Your email address will not be published. Required fields are marked *