1 Regulation of gene expression prokaryotes eukaryotes gene activity is regulated primarily at the level of transcription

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4 A.lactose operon (lac operon) a.concept of operon b.type of operon inducible operon repress operon

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6 阻遏性蛋白 基因关闭 负调 调控区 激动蛋白 基因开放 正调

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8 c. Structure of lactose operon * inducer of lac operon allolactose isopropylthiogalactoside (ITPG) * repressor of lac operon # formation # character of structure

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13 d. mechanism of the regulation e. The action of CAP-cAMP complex in lac operon * CAP ( catabolic gene activator protein) # structure

14 two domain one bind DNA one bind cAMP * the function of cAMP stimulated many reducible operon

15 cAMP （饥饿信号） 细菌哺乳类动物 激活 PK 与分解物基因结合物蛋 白结合 （ catabolite gene activator protein,CAP ） 发挥作用 导致细胞内一系 列酶活性的改变

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23 葡萄糖 cAMP ， CAP- cAMP 复合物与启动子上 游 基因结合 高乳糖 低乳糖 乳糖与阻遏物结合 阻遏物与操纵基因结合 结构基因表达 结构基因表达抑制 乳糖利用 乳糖不被利用

24 B 、 葡萄糖 ， cAMP ， CAP- cAMP 复合物 结构基因表达 乳糖不被利用

25 2. The general condition of regulation of gene expression in prokaryotes (1) the change of environment (2) positive regulation & negative regulation

26 negative regulation repressor of lac bind to operator Positive regulation CAP-cAMP complex

27 B.trytophan operon (Trp operon ) a. Structure b.mechanism of regulation *negative regulation of repressor # the structure of repressor # attenuation

28 Attenuator located in L gene,contains a  independent termination structure # the mechanism of attenuation

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30 大肠杆菌 低 Trp 培养基高 Trp 培养基 转录生成 6720 个 AA 的全长多 顺反子 mRNA 转录终止于 L 基 因 5’ 端 140 个 AA

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36 Trp Trp-tRNA 片段 3 、 4 形成不依赖 ρ 因 子的转录终止结构 核糖体停在 2 个相邻 Trp 位置上，片段 2 、 3 形成反终止结构 RNA Polymerse 转录终止 RNA Polymerse 转录进行

37 2. Regulation of gene expression in eukaryotes (1) character of regulation (2) activation of chromatin

38 (3) cis- acting elements & trans – acting factors involved in gene regulation a. cis-acting elements * concept * type

39 # Promoter & proximal upstream sequences according to its function of affecting to RNA pol far from the transcription site two kinds (-CAAT-,GC box) near the transcription site (TATA box)

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41 # inhancer concept character # response elaments concept character

42 b. trans – acting factors * concept * structure bind to cis-element two domain activity domain

43 * the mechanism of its functure * modles of trans-acting factors # helix-turn helix structure helix---turn---helix (7-9A.A) (7-9A.A)

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47 # zinc-fingers structure character # leucine –zipper structure character

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52 # helix-loop-helix structure * The character & rule of trans-acting factors’ function

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