Lecture 5 Flashcards
What was the ptolernian model? For how long was it accepted? What came after?
A geocentric system model. A mathematical model. The model uses epicycles (circle moving on circle). Accepted until 1543 A.D. Then AArstarchus of Samos came up with a heliocentric model.
What is astrobiology?
Astrobiology is the study of the origin, evolution, distribution and future of life in the whole Universe.
What is a superplume?
A superplume is a large mantle plume that spreads at the base of the lithosphere flattening the plume head to 1500 to 3000 km in diameter.
What is Metazoan life?
Any of a group (Metazoa) that comprises all animals having the body composed of cells differentiated into tissues and organs and usually a digestive cavity lined with specialized cells.
What was the “Cambrian explosion”?
About 541 Myr ago.
The “Cambrian explosion” consist of two phases of metazoan expansion into empty niches:
first, an unprecedented rise in diversity as animals explored niches on the bottom of the sea,
a second expansion in the early Cambrian as metazoan life becomes established in the water column
The rate of diversification seen in the Cambrian phase of the explosion is unparalleled among marine animals
This is when life went from simple organisms to more complex species and started showing up in fossil records
What is Occams razor?
The idea that scientists should prefer the simpler of two models
What are the issues of astrobiology?
What is life?
Cells and the chemistry of life
RNA and DNA life
Extremophiles – do they tell us something?
Could life be very different?
How likely is life to arise?
When approximately did Life start to form?
3.8 Gyrs ago
What early lifeform changed the atmosphere and how?
Cyano bacteria produced free oxygen.
What is required to build DNA?
Energy Amino acids Concentration of chemicals Catalysts Protection from heat and cold and radiation
What are the steps to build DNA?
The synthesis and accumulation of molecules like amino acids, phosphates (”backbone” of DNA and RNA) and nucleotides
The joining of these small molecules into larger molecules like proteins and nucleic acids
The accumulation of proteins and nucleic acids into a localized container (the pre-cursor to the cell) which became different to its environment
The replication of the larger complex molecules. The initiation of heredity
Amino acids, phosphates & nucleotides -> Proteins and nucleic acids accumulated into localized container - > replication of larger complex molecules -> heritage
What process diminished the greenhouse effect and cooled the earth?
The change from CO2 to O2 in our atmosphere.
What was the Stanley Miller experiment?
An experiment to simulate the early conditions of the earth. This produced glycin, the simplest amino acid and showed signs of about 20 others. The experiment showed that simple organic compounds of of building blocks of proteins and other macromolecules can be formed from gases with the addition of energy.
Describe how the Stanley Miller experiment was performed.
The experiment used water, methane, ammonia and hydrogen. These chemicals were sealed inside a sterile 5-liter glass flask connected to a 500 ml flask half-full of water. The water in the smaller flask was heated to induce evaporation and the water vapor was allowed to enter the larger flask. Continuous electrical sparks were fired between two electrode in the larger flasks to simulate lightning in the water vapor in the gas and vapor mixture. Then the simulated atmosphere was cooled again so the water condensed and trickled into a u-shaped trap at the bottom of the apparatus. After a week the the boiling flask was removed and mercuric chloride was added to prevent microbial contamination. The reaction was then stopped by by adding barium hydroxide and sulfuric acid and evaporated to remove impurities. The experiment laid ground for more similar experiment with different conditions and even “simulating” volcanoes to find more organic compounds.
What is the problem with forming proteins in the amino acids -> primitive proteins -> life model?
In order to form proteins you need nucleic acids and in order to form nucleic acids you need proteins. Chicken and egg problem.
What is the drake equation (1961)?
An equation which calculates the number of civilizations in our galaxy with which radio-communication might be possible.
What is the biggest problem in interstellar travel?
The interstellar distances. We need a few % of c as speed.
