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【单选题】
CRISPR/Cas is a powerful approach to edit genes. “CRISPR” stands for clustered, regularly interspaced short palindromic repeats; as the name suggests, these consist of a series of regularly spaced short repeats in the bacterial genome. A Cas (CRISPR-associated) protein is a nuclease. Which of the following statements is wrong?A.
The CRISPR sequences and Cas protein are components of a kind of nervous system that evolved to allow bacteria to survive infection by bacteriophages.
B.
CRISPR sequences are embedded in the bacterial genome, surrounding sequences derived from phage pathogens that previously infected the bacterium without killing it. The viral sequences are, in effect, spacer sequences separating the CRISPR sequences. When the same bacteriophage again attacks a bacterium with the corresponding CRISPR/Cas system, the CRISPR sequence and Cas protein act together to destroy the viral DN
C.
First, the CRISPR sequences are transcribed to RNA, and individual viral spacer sequences are cleaved to form products called guide RNAs (gRNAs), which include some adjacent repeat RN A gRNA forms a complex with one or more Cas proteins and, in some cases, with another RNA called a trans-activating CRISPR RNA, or tracrRN
D.
The resulting complex binds specifically to the invading bacteriophage DNA, cleaving and destroying it through the nuclease activities associated with the Cas proteins.
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【多选题】中国新民主主义革命任务要分两步走,( )。
A.
第一步是完成建立新中国的任务
B.
第二步完成建设新中国的任务
C.
第一步完成反帝反封建的新民主主义革命任务
D.
第二步是完成社会主义革命任务
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【简答题】中国新民主主义革命任务要分两步走,( )。A. 第一步是完成建立新中国的任务 B. 第二步完成建设新中国的任务 C. 第一步完成反帝反封建的新民主主义革命任务 D. 第二步是完成社会主义革命任务
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