W3L2 - Origin of Life 1 Flashcards
What are some experiments disproving spontaneous generation of life: First
1668 Francesco Redi
1. 1668 Francesco Redi
- Boiled meat. Covered vs uncovered.
- Covered meat: Ok
- Uncovered meat: Maggots (which turned into flies)
- Can’t get maggots just popping out, need other life
What are some experiments disproving spontaneous generation of life: 2nd
1745 John Tuberville
- 1745 John Turberville (catholic)
- Boiled broth and placed in a flask
- Microbes grew and spoiled the broth
- Can’t get microbes just coming out
What are some experiments disproving spontaneous generation of life: 3rd
1779 Lazzaro Spallanzani
3. 1779 Lazzaro Spallanzani
- Boiled broth, seal flasks, no growth
- Also did:
- Echolocation
- in vitro fertilization
- artificial insemination
- digestion
Since life cannot arise de novo, what is the first theory? (3)
1. Panspermia
- Life arrived from another planet
- Meteorites contain organic matter (‘life’)
- Spectra indicates organic material in comets
In panpsermia, how did life start? (4)
What is an evidence for panspermia
- Life got started pretty quickly after the heavy bombardment of Earth
- Life probably existed on a wet Mars long before it got started on Earth
- Life can survive a long time in stasis (freeze-dried yeast)
- Life could survive an intra solar system journey inside a largish rock shielded from radiation
Murchison meteroite 1962:
- 92 different amino acids (“building blocks”) with 73 not known on earth
What is the Mars Meteroite? (2)
- Gouged off Mars 15 million years ago and hit Antarctica 13,000 years ago
- But….. ‘cells’ are only 10-30nm; far smaller than any known cell (Folded RNA cannot fit between phospholipid bilayer - too small for ‘Life’)
What are Nanobes? (3)
- Argued to be ultra-small bacteria
- Grow on minerals
- So far, no one saw DNA and no one could get it cultured
What is nanobacteria? (3)
- Dwarf forms of bacteria
- 0.05 to 0.2 um - 1/10 diameter and 1/1000 volume of normal bacteria
- Recovered from range of diseased tissues including kidney stones
- Claim to find RNA in nanobacteria
TLDR Paspermia
Far fetched but still plausible
Have evidence for and against
What is the hallmark of living things?
Macromolecules (polymers of monomers) are a hallmark of living things
- DNA - Polymer of Bases
- Lipid - Carbon Chains
- Proteins - Polymer of Amino Acids
- Carbohydrates - Polymer of Sugars
What is the theory behind how monomers come from (3)
Oparin/Haldane Theory
- Early earth atmosphere was reducing
- No oxygen gas (No ion oxides could be found in rocks)
- Continuous spontaneous creation of organic molecules due to molecule-promoting environment
- Cell-like structures (co-acervates) arose spontaneously
What are Coacervates? (3)
- Spherical aggregation of lipids held together by hydrophobic forces
- 1μm to 100μm in diameter
- Absorb molecules from their environment, grow & divide
What is Stanley Miller’s apparatus? And what did it demonstrate? (2)
Heat source on H2O > Gas inlet of CH4 (Methane) and NH3 (Ammonium) > Spark to integrate everything (H2O, CH4 , NH3 , H2 , CO2 ) > Condense to liquid to observe
Demonstrated that:
- Basic elements + Energy > Generate many proteins
- Hence, monomers might have been there for a long time
What does it mean when something is “organic” (4)
Organic = carbon containing
- Carbon has a valence of four, many options
- Forms very strong covalent bonds
- Abundant
- Latches on to many other atoms and thus can build lipids, carbohydrates, proteins, DNA
Why carbon not silicon? (3)
- Silicon has same valence
- Abundant
- Forms slightly weaker covalent bonds
