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阿棟 asked in 科學其他:科學 · 1 decade ago

生物問題一問,盡可能用原文回答 <20點>

請問Q1:何謂搖擺理論(wobble theory)?

Q2:說明Lytic與Lysogenic cycle?

Q3:說明 lac operon?

1 Answer

  • 1 decade ago
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    Q1.Wobble Theory: One of the co-discoverers of the structure of deoxyribonucleic acid. The hypothesis explained the mechanics of part of the translation process, where information carried on the messenger RNA is recognized and used to manufacture protein. Specifically, the wobble theory addresses how the limited number of transfer RNA (tRNA) molecules are able to recognize all the combinations of codons--three base sequences of amino acids--on the messenger RNA. Recognition of these codons by tRNAs is an absolutely vital step in protein synthesis.The tRNAs read the mRNA codons in a specific manner. Q2.LYTIC AND LYSOGENIC CYCLE : There are a couple of different ways to do this activity. It can either be done as a skit in which the teacher explains the role to each person, or materials can be given to the students and they create a skit to show that they understand the concepts. The focus of the activity is to show the different stages in the Lytic cycle and the difference between it and the Lysogenic cycle. Our version of the activity requires the following for each cycle: Q3.Illustration of the method by which the lac operon is nscribed:Gene transcription can be switched on and off by gene regulation proteins. The lac operon in E.Coli is an example of that dual control. Glucose and lactose levels control the initiation of transcription of the lac operon, i.e. whether the lac operon is switched "ON" or "OFF".In an E. Coli cell growing in the absence of lactose, a repressor protein binds to the operator, preventing RNA polymerase from transcribing the lac operon's genes. The operon is OFF. When the inducer, lactose, is added, it binds to the repressor and changes the repressor's shape so as to eliminate binding to the operator. As long as the operator remains free of the repressor, RNA polymerase that recognizes the promoter can transcribe the operon's structural genes into mRNA. The operon is ON.

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