Bio Chp. 14
Extraterrestrial Origins (Panspermia)
(life on earth was "seeded" from OUTER SPACE) Evidence of organic compounds HAS been found in recovered meteorites. The Murchison (Aus, 6/20) and Murray (KY, Glucose sugars and amino acids) meteorites are some of the best-studied examples.
The first life forms arose on earth sometime after the planet cooled about
4 billion years ago
What is an autotroph? What factors helped them thrive on Earth?
An autotroph is an organism that can produce its own food, they were able to thrive on earth because of the abundance of chemicals, which many were able to use to produce food
What present-day organisms may be similar to the earliest autotrophs? Why?
Archae bacteria, they are chemosynthetic autotrophs dwelling near sources of sulfur and methane, much lke first autotrophs they are anaerobic
20. Pasteur hypothesized that many chemical reactions occurring in the atmosphere resulted in the formation of a "primordial soup "of organic molecules.
F; Oparin
19. In the early 1900s, Alexander Oparin proposed a widely accepted hypothesis that life began on land.
F; in the sea
17. Several billion years ago, Earth's atmosphere had no free methane.
F; oxygen
15. Biogenesis explains how life began on Earth.
False; doesn't explain
Louis Pasteur 19th cent
S-shaped neck flasks
18. Primitive Earth's atmosphere may have been composed of water vapor, hydrogen, methane, and ammonia.
True
Radiometric dating
age determined by elements/isotopes in the rock, such as c-14, k-40, and u-238
22. Miller and Urey showed that organic compounds, including nucleic acids and sugars, could be formed in the laboratory, just as Oparin had been predicted.
amino acids
Spallanzani 18th cent
broth sterilized w heat and corked = no microbes broth sterliliez w heat left uncorked = mucho microbes
What tommy cech mean by calling early earth RNA World
cells first contained only RNA b/c RNA is much simpley and can carry out chem (act as enymze) reactions as well as carry genetic code
24. Sidney Fox took Miller and Urey's experiment a step further and showed how amino acids could cluster to form protocells.
f; microspheres
16. For life to begin, first, simple inorganic molecules had to be formed and then organized into complex molecules.
fasle; organic
1/2 life
how long to decay to a stable state 1/2 way
Whats the dif between a coacervate and a microshpere
micros- round blobs made of protein molecules and surrounded by membrane Coacervate - collection of droplets composed of molecules of diff. types of organics
Law of Superposition
more recent is first rock
23. This "life-in-a-test-tube" experiment of Miller and Urey provides support for some modern theory of biogenisis.
origin of life (Chemosyntheisis
Francisco Redi 17th cent
rotting meat
Chemosynthesis (origin)
the theory that chemical reactions occurred here on young earth that resulted in (1) first organic compounds forming and then (2) cells forming from these. This is by far the most popular scientific theory and probably the best-supported by testable, factual evidence.
What change occurred in Earth's atmosphere after the evolution of photosynthesizing prokaryotes? Why?
there was much more oxygen in the atmosphere because it is produced as a byproduct of their food making process, and a layer of ozone (o3) developed, along with cloud coverage
ribozyme
type of RNA molecule that can act as both genetic coding and enzyme for specific chem. reaction
Relative Dating
which organisms preceeded the others, uses relative pos. in Strata earth rocks and Law of Sup to determine age of life
Gases in miller urey chamber
Methane, ammonia, water vapor, hydrogen
25. Describe the likely characteristics of the first organisms on Earth.
Prokaryotes, single celled, anaerobic, probably heterotrophic
Oparin
Proposed Chemosynthesis, rejeted b/c sounds like spont. gen, throught many chem reactions in atmosphere = prmordial soup