WEEK 2: History and Evolution of Life on Earth Part I

On the second week, we learned about evolution of life on earth part 1. We learned how macromolecules exist on this earth and the formation of eukaryotes and prokaryotes. As a summary, small inorganic compound that maybe had been brought by comets and asteroids from the outer space went through a chemical evolution and became larger organic compound. Referring to prebiotic broth hypothesis, the organic molecules formed near Earth’s surface. Then, the organic molecules polymerized into larger molecules such as protein and nucleic acid. Next, primitive RNA molecules were packaged within a membrane which called protobionts. 

 

Successful protobionts will grow and split. Distribute copies of their heredity to offspring. Coacervate is one of the possible protocell. It is a tiny spherical droplet of assorted organic molecules which is held together by hydrophobic forces.

 Natural selection at molecular level resulted in DNA. DNA is more stable and easy to pack. After that, from DNA, it became prokaryotes. At first, prokaryotes were chemoautotrophs which consumed organic molecules for both energy and carbon. Then, they became autotrophs because of evolution. They consumed light and similar to sulfur bacteria today. For instance, cyanobacteria, it acted like a chloroplast and released oxygen to the atmosphere. This lead to the extinction of many anaerobic organisms. Natural selection occurred, favour those prokaryotes that can tolerate with oxygen. Finally, eukaryotes formed. This is what I understand after I tried to read the notes and asked my friends about this topic. My lecturer also asked the class to do a mind map about this topic by using the terms that had been given on the student portal. This activity also helped me to understand this topic. Actually, I was not really agree to do this kind of activity because on that time I was not understand about this. I did not know how to relate all the mechanisms and how it connected each other but after I did the mind map, I could see the relation and the path from one to another. That activity also encouraged myself to look for information. If you do not understand about something and your lecturer pushed to do the mind map, it will trigger yourself to find an effort to understand about that lesson. This is from my personal view how some activities can give benefits to ourselves. I am still looking forward about this topic as I am afraid if what I understand before could be wrong at some points.