SAT化学知识点讲解

　　SAT化学考试中知识点很多，新航道小编整理SAT化学知识点-Protein Synthesis讲解，供大家参考。

　　Transcription

　　The first step in transcription is the partial unwinding of the DNA molecule so that the portion of DNA that codes for the needed protein can be transcribed. Once the DNA molecule is unwound at the correct location, an enzyme called RNA polymerase helps line up nucleotides to create acomplementary strand of mRNA. Since mRNA is a single-stranded molecule, only one of the two strands of DNA is used as a template for the new RNA strand.

　　The new strand of RNA is made according to the rules of base pairing:

　　DNA cytosine pairs with RNA guanine

　　DNA guanine pairs with RNA cytosine

　　DNA thymine pairs with RNA adenine

　　DNA adenine pairs with RNA uracil

　　For example, the mRNA complement to the DNA sequence TTGCAC is AACGUG. The SAT II Biology frequently asks about the sequence of mRNA that will be produced from a given sequence of DNA. For these questions, don’t forget that RNA uses uracil in place of thymine.

　　以上是SAT化学知识点-Protein Synthesis讲解，更多SAT化学信息可以参看新航道SAT频道。

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