Unit 2: Origins of Life: Intro Flashcards
1
Q
Earth forms
A
4.6 BYA
2
Q
Prokaryotes form
A
3.5 BYA
3
Q
Early earth atmosphere
A
H20, CO2, CH4, NH3
N2, CO2, H2S, CH4, CO, H2, NH3 H2O, HCN
4
Q
Early earth environment
A
- Meteor impacts, lots of lighting, no fire(no O), hot, volcanic eruptions, radiation from sun
- Destructive, but lots of ENERGY
5
Q
Early earth began with
A
No organic molecules
6
Q
Chemical evolution hypothesis
A
Said organic molecules could have formed from the compounds of Early Earth Environment
7
Q
Miller-Urey experiment
A
- Water is heated Water vapor forms
- Mix of NH3, CH4, H20, H2 added to atmosphere
- Circulating gases are bombarded by sparks of electricity
- Cold water cools chamber causing droplets to form
- After a week liquid is collected containing amino acids, sugars, lipids, and other organic compounds.
8
Q
1
A
- abiotic synthesis of organic monomers, such as amino acids, and nitrogenous bases
- The synthesis could have occurred in the early oceans, using energy from lightning or radiation.
9
Q
2 - Polymerization
A
- these monomers spontaneously joined into polymers, in particular, nucleic acids and amino acid polymers.
- Could have happened in hydrothermal vents, edge of ocean, volcanoes
- Researchers have been able to reenact this step by dripping amino acid solutions onto hot sand, clay, or rock, which act as catalysts
10
Q
3 - Protocells/Coacervate
A
- Phospholipid membrane bubbles with some molecules trapped inside
- Inside different from outside
- Phospholipids do this spontaneously in water - hydrophilic heads/hydrophobic tails
11
Q
4 - Heredity
A
- Nucleotides assembled
- Some form of self replication
- RNA
12
Q
Why RNA not DNA
A
- DNA is more structurally complex
- Requires more enzymes for replication + function
- These specific proteins may have existed, but more likely that RNA came first
- Deoxyribose + thymine probably appeared after ribose + uracil
13
Q
Prokaryotes
A
- Small
- No membrane bound organelles or nuclear envelope
- Small ribosomes
- Circular chromosomes
- Cell walls made of peptidoglycan
14
Q
Heterotroph/Autotroph
A
Heterotroph - Cannot make its own organic molecules
Autotroph - Can synthesize own organic molecules
15
Q
Earth had a reducing atmosphere
A
- Lacks free oxygen
- may contain such reactive gases as hydrogen or carbon monoxide that oxidize in the presence of oxygen, such as hydrogen sulfide.
