Early Planet: Early Life Flashcards
How long ago was the formation of th Earth
4.6 Billion years ago
How did the solar system form
The solar system formed from an interstella cloud
This is a region of dust and hydrogen, which contracted under its own gravity
The Sun formed in a Hot and Dense centre of the cloud and the rest formed a disc called a solar nebula
How did the Earth’s Moon form
In a giant impact event ca. 4.51 billion years ago
The Debris from this collision between Earth and Theia (a body the size of Mars) was used in the formation of the Moon
What is the Late Heavy Bombardment (LBH) and when did it occur?
An estimated 17,000 large coments and asteroids bombarded Earth 3.8-3.9 billion years ago, making the Earth’s surface hundreds of degrees hotter than the highest temperature at which amino acids/nuclueodies can survive undamaged, hence destroying any possible previous life before that
How does the start of life link to the Late Heavy Bombardment
Life as we know it, is though to have started 3.9 billion yearsa go after the Late Heavy Bombardment, as life before this would have been whipped out
Give some examples about how life on Earth can survive in the most extreme places
Antartica (-94.7 degrees recorded in 2010)
Strain 121m - a microbe found on some hydrothermal (volcanic) vents in the Pacific) survived a ten-hour blast in an autoclava at 121 degrees
Hypersaline springs
Toxic waste dumps
Cracks deep in the Earth’s crust and saline brine in oil fields
What is the main two difference between prokaryotic and eularyotic cells
Prokaryotes do not have a nucleus
Prokaryotes do not have membrane-bound organelles
Which life form evolved first eukaryotic or prokaryotic
Prokaryotic life forms evolved first, and dominat the would unseen today and are fundamental to most biogeochemical cycles and processes
Eukaryotes evolved much later (1.7-2.0 bya) and eventually clubbed together to form multiceulluar organisms
Name two ways of how life could have originated on Earth
Life must have arrived from elsewhere or was created on our planet, as early conditiion were such that nothing could have lived on it
What organism is believe to be the earliest form of life and what evidence exists for this
Archeae (4.0-2.5 bya)
Archean rocks are found around the works, which are cherts. They are almost pure silica (glass) and yield apex fossils (form in aqueous environments)
They are believed to be formed through both seawater and hydrothermal fluids
Evidence of their age can come from the silicon isotopes in the cherts
The cherts give evidence of life how many years ago
They give evidence of life as far back as 3.5 billion years ago
When chemical evidence exists for the presence of early life
The Great Oxygenation event and Carbon isotope evidence shows that like was operting around 3.8-3.5 bya
Going from unicellular to multicullular organisms, how long did this progression take to occur
There is a big gap in time between the existence of singular and multi-celled organisms
How does the occurence of elements relate to the formation of Earth and life
Chemical elements made in the starts and spread through the universe when start explode - supernova
Elements become rarer as they get heavier. The study of both the Eath and life revolved largely around subsets of the first 30 elements
> 90% of the non-living planet is made up of what 4 elements
Oxygen, Magnesium, Silicon and Iron
What are Lithophile and Siderophile elements and how did they affect the formation of the Earths core
Lithophile - rock loving
Siderophile - iron loving and also iron
Lithophile and siderophile elements and elements that combine with oxygen are preferentially incorporated into rocks and metallic core when Earth formed, leading a relative deficiency at the surface (this includes mainly oxygen, magnesium, silicon and iron)
What elements have little-to-no role in life and why?
The unreactive noble gases
They do not play a significant role in low-temperature chemical systems, such as life as they are fully intert
Hence, they are only found on their own and don’t play any part in life/biological systems
How does the composition of the sun link to formation of life
For the lightest chemical elements (minus the lithophile/siderophile elements and noble gases) there is a strong correlation between the composition of the Sun and of all of life
Life statically has a great deal in common with the composition of the sun
Carbon and Silicon are two different elements in the centre of the periodic table, that are fundamental to the composition of the planet and of life, what is the common feture between the two
And what does it show about elements involved in life
They both have a valence of +4
Elements involved in life need to be reactive
Silicion is highly reactive with oxygen forming silicon dioxide (silica) and can form either glass or quartz
What is the difference between these two compounds
The multiple bonding capabilities of silicon gives us the main structural component of rocks - quartz, which is a more ordered crystalline structure than glass
What is the difference between the silicon structures which form like silicion dioxide and organic compounds which form
Carbon can form 3D complexes in a similar way, but with carbon you get not brittle crystals but soft and pliable structures, and more reactive than silicon
What are 5 advantages of Carbon over Silicon for life
- Can bond to itself as well as other elements: C-C backbones
- Can be and fold to make much more complex structures than silicon, which is rigid and inflexible
- Can form molecules that are soild (bone/wood(, liquid (oil), and gas (carbon dioxide and methane), allow exchange of carbon between different phases of matter
- Can form soluable and insoluable molecules, usful for transporting carbon or making carbon resistant to water damage
- Can have mutiple eletrical states e.g +4 in carbon dioxide and 4- in methane
Why is it then, that life is made up only of a small number of elements
Because of the elements that carbon bonds with and that are available at the Earth’s surgave in sufficient amounts
What are 4 key biological organic molecules which are associated with all forms of life
Carbohydrates
Lipids
Amino acids
Nucleic acids
What where pre-life condition like on Earth: specifically the oceans and atmosphere
Oceans: liquid water was present, the sea water salty and contains cations (sodium, magnesium and calcium) and anions (chloride) and around similar levels of today
Atmosphere: was moderately reducing (rather than oxygen-rich), the sun was 30% dimmer, and high levels of CO₂ kept the earth warm
Overall it was still contusive for life
How is life on a basic level, thought to have come about
Organic biological molecules were made abiotically
Monomers for polymers and they where enclosed in a cellular container
And these cells replicated and evolved via natural selection
What is a major stumbling block in the theory of abiotic synthesis of basic building blocks of life
They synthesised organic biological molecules would have been created in dilute concentrations and many had short lifespans, e.g., an amino acid made in the atmosphere by lightening is carrier to the ocean by rainwater, where it is unlikely to meet another potential life molecules
An environment in which life molecules are concentrated and hence comes together, is a hurdle
However there are many theories for this like primordial broth
Many theories for getting the biological organic molecules together are highly distributed, for example: evaporative intertidal lagoons, concentration of molecules of mineral surfaces, clouds or subsurface cracks on rocks
Deep sea vents seems like quite a likely hypothesis: explain?
Strong chemical concentrations, favourable conditions for chemical reactions, abundant energy, metal catalysts, all could aid in the synthesis of diverse organic molecules now thought to be possible by the mixing of hot geothermal fluids within seawater
There is also no shortage of these geothermal vent across planet Earth
