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9.1 - Earth Forms and Life Begins (The Fossil Record (Relative Dating:…
9.1 - Earth Forms and Life Begins
Earth In A Day
if earth took place in 24 hours we would be in the very last minute of the day
The Fossil Record
Relative Dating:
Relative dating is the science of determining
the relative order of past events
Absolute Dating:
Absolute dating is the process of determining an age on a specified chronology in archaeology and geology
Molecular Clocks
the average rate at which a species' genome accumulates mutations, used to measure their evolutionary divergence and in other calculations
How Earth Formed
The Earth is thought to have been formed about 4.6 billion years ago by collisions in the giant disc-shaped cloud of material that also formed the Sun. Gravity slowly gathered this gas and dust together into clumps that became asteroids and small early planets called planetesimals.
The First Organic Molecules
Scientists think that lightning sparked chemical reactions in Earth's early atmosphere. The early atmosphere contained gases such as ammonia, methane, water vapor, and carbon dioxide. Scientists hypothesize that this created a “soup” of organic molecules from inorganic chemicals.
RNA World Hypothesis
the rna hypothesis states that life later evolved to use DNA and proteins due to RNA's relative instability and poorer catalytic properties, and gradually, ribozymes became increasingly phased out. The ribosome, a large molecular machine that drives protein synthesis, is a ribozyme.
The First Cells
The first cells consisted of little more than an organic molecule such as RNA inside a lipid membrane. One cell (or group of cells), called the last universal common ancestor (LUCA), gave rise to all subsequent life on Earth. Photosynthesis evolved by 3 billion years ago and released oxygen into the atmosphere.
Photosynthesis & Cellular Respiration
Photosynthesis makes the glucose that is used in cellular respiration to make ATP. The glucose is then turned back into carbon dioxide, which is used in photosynthesis. While water is broken down to form oxygen during photosynthesis, in cellular respiration oxygen is combined with hydrogen to form water.
Evolution of Eukaryotes
Endosymbiotic Theory of Evolution of Eukaryotic Cells. THE THEORY: The mitochondria and chloroplasts of Eukaryotic cells arose from the symbiotic incorporation of prokaryotic cells by a proto-eukaryotic cell. ... Eukaryotic cells originated more than 0.6 billion years ago.
