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【多选题】
How do transcription regulators, general transcription factors, and RNA polymerase gain access to the underlying DNA in highly packed chromosomes?A.
In eukaryotic cells, activator and repressor proteins can exploit the mechanisms used to package DNA to help turn genes on and of.
B.
Chromatin structure can be altered by chromatin-remodeling complexes and by enzymes that covalently modify the histone proteins that form the core of the nucleosome. Many gene activators take advantage of these mechanisms by attracting such chromatin-modifying proteins to promoters.
C.
For example, the recruitment of histone acetyltransferases promotes the attachment of acetyl groups to selected lysines in the tail of histone proteins; these acetyl groups themselves attract proteins that promote transcription, including some of the general transcription factors. And the recruitment of chromatin-remodeling complexes makes nearby DNA more accessible. These actions enhance the efficiency of transcription initiation.
D.
In a similar way, gene repressor proteins can modify chromatin in ways that reduce the efficiency of transcription initiation. For example, many repressors attract histone deacetylases—enzymes that remove the acetyl groups from histone tails, thereby reversing the positive effects that acetylation has on transcription initiation.
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【简答题】A．P B．I C．O D．E E．S 在护理记录中，健康问题采取的护理措施的英文简称为
【单选题】对域名www.sina.com中“www”的说法不正确的是( )
A.
它的中文简称是万维网
B.
它是一种网络服务
C.
它的域名组成中代表主机名
D.
它是一种网络协议
【单选题】对域名www.sina.com中“www”的说法不正确的是()
A.
它的中文简称是万维网
B.
他是一种网络服务
C.
它的域名组成中代表主机名
D.
它是一种网络协议
【单选题】对域名“www.sina.com”中“www”的说法不正确的是( )。
A.
它的中文简称是万维网
B.
它是一种网络服务
C.
它在域名组成中代表主机名
D.
它是一种网络协议
【单选题】下面隐式对象中,用于获取指定请求参数的一组值的是()(单选)
A.
param
B.
applicationScope
C.
paramValues
D.
paramScope
【单选题】患者,女,56岁。因腹泻,未进食2天入院。入院时头晕,全身乏力,恶心,呕吐,尿量减少,轻度口渴。化验:血钠133mmol/L,血钾3.56mmol/L。下列诊断最可能的是
A.
低渗性脱水
B.
低钾血症
C.
等渗性脱水
D.
低钠血症
E.
等渗性脱水
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