WEEK 2
HELLO EVERYONE..... we meet again for my second week. I'm sure you all wondering right why I write week 1 for the past one and week 2 for this one. Actually this is my assignment for subject cellular and developmental biology. This assignment was called as reflective learning journal blog.
The purpose of the assignment assign to us are to show student ability to communicate in writing, to give opportunity to students to share activities and what they feel during study the subject of cellular and developmental biology. So today i will share with you all what i learn in week 2. In week 2 i learn about History of Life Part1.
Scientist say that the diversification of life started 3.8 billions ago and 3.3 billions ago the earliest unicellular life/ bacteria/ stromatolites/ cyanobacteria exists. But how did life begin? Life begin from molecules to cell. the first cell exist from abiotic synthesis of small organic molecules and then the small organic molecules bonding to each other and form macromolecules. packaging macromolecules into protobionts.
Protobionts is an aggregation of organic molecules, surrounded by a membrane, that abiotically coalesces into resemblances of living matter; thought to be the precursors of prokaryotic cells. From protobionts the first RNA was produced. Yup from here you can known that RNA come first before DNA. WHY??? Because DNA can only copy themselves with the help of enzymes but single RNA strand can copy in solution containing nucleotides without enzymes. Also, RNA has the molecule called ribozymes that can make complementary copies of short stretches of their own or other short pieces of RNA. Because of this resulting the self-replication molecules. All of this happen because of chemical evolution. For the chemical evolution occur there are 4 requirement:
1) little or no oxygen.
2)source of energy to form organic molecules-early earth was a place of high energy.
3) Availability of chemical building blocks such as CO2, N2, CO and water vapour.
4) sufficient time for molecules tp accumulate and react.
In history of life it not valid if we not talk about 'Prebiotic Broth Hypothesis". this hypothesis proposes that organic molecules formed near earth's surface-in a sea of organic soup or on rock or clay surfaces.
The early Earth was has little oxygen but then become more oxygen because
the existence of cyanobacteria. Cyanobacteria is the first photoautotrophs that used light to drive electron from water instead of H2S to fix CO2 into sugar. This is because the evolution of prokaryotes that act like chloroplast. It happen about 2.5 billions ago and it caused the extinction of many anaerobic organisms and evolution of aerobic respiration-evolution of prokaryotes that act like mitochondria.
Okey the end for the part 1. For the first time i study about history of life it very confusing but with the help from my friends i think i understand about it a bit. And then our lecture give us a group work to make mind-map for this chapter make me become more understand about this chapter. Thanks to our lecture i can known about our prior existence in more detail... THANK YOU. That all for today.. thank you. and wait for my third week.. bye2..
The purpose of the assignment assign to us are to show student ability to communicate in writing, to give opportunity to students to share activities and what they feel during study the subject of cellular and developmental biology. So today i will share with you all what i learn in week 2. In week 2 i learn about History of Life Part1.
Scientist say that the diversification of life started 3.8 billions ago and 3.3 billions ago the earliest unicellular life/ bacteria/ stromatolites/ cyanobacteria exists. But how did life begin? Life begin from molecules to cell. the first cell exist from abiotic synthesis of small organic molecules and then the small organic molecules bonding to each other and form macromolecules. packaging macromolecules into protobionts.
1) little or no oxygen.
2)source of energy to form organic molecules-early earth was a place of high energy.
3) Availability of chemical building blocks such as CO2, N2, CO and water vapour.
4) sufficient time for molecules tp accumulate and react.
In history of life it not valid if we not talk about 'Prebiotic Broth Hypothesis". this hypothesis proposes that organic molecules formed near earth's surface-in a sea of organic soup or on rock or clay surfaces.
Miller-Urey's experiment(1953)
In the 1950's, biochemists Stanley Miller and Harold Urey, conducted an experiment which demonstrated that several organic compounds could be formed spontaneously by simulating the conditions of earth early atmosphere.They designed an apparatus which held a mix of gases similar to those found in Earth's early atmosphere over a pool of water, representing Earth's early ocean. Electrodes delivered an electric current, simulating lightning, into the gas-filled chamber. After allowing the experiment to run for one week, they analyzed the contents of the liquid pool. They found that several organic amino acids had formed spontaneously from inorganic raw materials. These molecules collected together in the pool of water to form coacervates. Their experiments, along with considerable geological, biological, and chemical evidence, lends support to the theory that the first life forms arose spontaneously through naturally occuring chemical reactions.The early Earth was has little oxygen but then become more oxygen because
the existence of cyanobacteria. Cyanobacteria is the first photoautotrophs that used light to drive electron from water instead of H2S to fix CO2 into sugar. This is because the evolution of prokaryotes that act like chloroplast. It happen about 2.5 billions ago and it caused the extinction of many anaerobic organisms and evolution of aerobic respiration-evolution of prokaryotes that act like mitochondria.
Okey the end for the part 1. For the first time i study about history of life it very confusing but with the help from my friends i think i understand about it a bit. And then our lecture give us a group work to make mind-map for this chapter make me become more understand about this chapter. Thanks to our lecture i can known about our prior existence in more detail... THANK YOU. That all for today.. thank you. and wait for my third week.. bye2..
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