PPT模板紫色地球信息主题.ppt

《PPT模板紫色地球信息主题.ppt》由会员分享，可在线阅读，更多相关《PPT模板紫色地球信息主题.ppt（30页珍藏版）》请在三一办公上搜索。

1、单击此处编辑主标题,单击此处编辑副标题,单击此处编辑标题,正文部分样例A正文部分样例B正文部分样例C正文部分样例D正文部分样例I正文部分样例II正文部分样例III,单击此处编辑标题,正文部分样例A正文部分样例B正文部分样例C正文部分样例D正文部分样例I正文部分样例II正文部分样例III,正文标题,第一级第二级 第三级第四级第五级,正文标题,第一级第二级 第三级第四级第五级,样例文本A,Gemmi Cong 精美PPT模板尽在如下豆单欢迎大家欣赏和下载,样例文本A,Gemmi Cong 精美PPT模板尽在如下豆单欢迎大家欣赏和下载,样例文本B,At the ends of the linear

2、chromosomes are specialized regions of DNA called telomeres.The main function of these regions is to allow the cell to replicate chromosome ends using the enzyme telomerase,as the enzymes that normally replicate DNA cannot copy the extreme 3 ends of chromosomes.44 These specialized chromosome caps a

3、lso help protect the DNA ends,and stop the DNA repair systems in the cell from treating them as damage to be corrected.45 In human cells,telomeres are usually lengths of single-stranded DNA containing several thousand repeats of a simple TTAGGG sequence.46DNA quadruplex formed by telomere repeats.Th

4、e looped conformation of the DNA backbone is very different from the typical DNA helix.47These guanine-rich sequences may stabilize chromosome ends by forming structures of stacked sets of four-base units,rather than the usual base pairs found in other DNA molecules.Here,four guanine bases form a fl

5、at plate and these flat four-base units then stack on top of each other,to form a stable G-quadruplex structure.48 These structures are stabilized by hydrogen bonding between the edges of the bases and chelation of a metal ion in the centre of each four-base unit.49 Other structures can also be form

6、ed,with the central set of four bases coming from either a single strand folded around the bases,or several different parallel strands,each contributing one base to the central structure.,样例文本B,At the ends of the linear chromosomes are specialized regions of DNA called telomeres.The main function of

7、 these regions is to allow the cell to replicate chromosome ends using the enzyme telomerase,as the enzymes that normally replicate DNA cannot copy the extreme 3 ends of chromosomes.44 These specialized chromosome caps also help protect the DNA ends,and stop the DNA repair systems in the cell from t

8、reating them as damage to be corrected.45 In human cells,telomeres are usually lengths of single-stranded DNA containing several thousand repeats of a simple TTAGGG sequence.46DNA quadruplex formed by telomere repeats.The looped conformation of the DNA backbone is very different from the typical DNA

9、 helix.47These guanine-rich sequences may stabilize chromosome ends by forming structures of stacked sets of four-base units,rather than the usual base pairs found in other DNA molecules.Here,four guanine bases form a flat plate and these flat four-base units then stack on top of each other,to form

10、a stable G-quadruplex structure.48 These structures are stabilized by hydrogen bonding between the edges of the bases and chelation of a metal ion in the centre of each four-base unit.49 Other structures can also be formed,with the central set of four bases coming from either a single strand folded

11、around the bases,or several different parallel strands,each contributing one base to the central structure.,样例文本C,脱氧核糖核酸有多种不同的构象，其中有些构象之间在构造上的差异并不大。目前已辨识出来的构象包括：A-DNA、B-DNA、C-DNA、D-DNA31、E-DNA32、H-DNA33、L-DNA31、P-DNA34与Z-DNA935。不过以现有的生物系统来说，自然界中可见的只有A-DNA、B-DNA与Z-DNA。脱氧核糖核酸所具有的构象可根据脱氧核糖核酸序列、超螺旋的程度与方

12、向、碱基上的化学修饰，以及溶液状态，如金属离子与多胺浓度来分类36。三种主要构象中以B型为细胞中最常见的类型37，与另两种脱氧核糖核酸双螺旋的差异，在于其几何形态与尺寸。其中A型拥有较大的宽度与右旋结构，小凹槽较浅且较宽，大凹槽则较深较窄。A型一般存在于非生理状态的脱水样本中，在细胞中则可能为脱氧核糖核酸与RNA混合而成的产物（类似酵素及脱氧核糖核酸的复合物）3839。若一段脱氧核糖核酸上的碱基受到一种称为甲基化的化学修饰，将使其构型转变成Z型。此时螺旋形式转为左旋，与较常见的右旋B型相反40。某些专门与Z-脱氧核糖核酸结合的蛋白质可辨识出这种少见的结构，此外Z型脱氧核糖核酸可能参与了转录作用

13、的调控41。,样例文本C,脱氧核糖核酸有多种不同的构象，其中有些构象之间在构造上的差异并不大。目前已辨识出来的构象包括：A-DNA、B-DNA、C-DNA、D-DNA31、E-DNA32、H-DNA33、L-DNA31、P-DNA34与Z-DNA935。不过以现有的生物系统来说，自然界中可见的只有A-DNA、B-DNA与Z-DNA。脱氧核糖核酸所具有的构象可根据脱氧核糖核酸序列、超螺旋的程度与方向、碱基上的化学修饰，以及溶液状态，如金属离子与多胺浓度来分类36。三种主要构象中以B型为细胞中最常见的类型37，与另两种脱氧核糖核酸双螺旋的差异，在于其几何形态与尺寸。其中A型拥有较大的宽度与右旋结构

14、，小凹槽较浅且较宽，大凹槽则较深较窄。A型一般存在于非生理状态的脱水样本中，在细胞中则可能为脱氧核糖核酸与RNA混合而成的产物（类似酵素及脱氧核糖核酸的复合物）3839。若一段脱氧核糖核酸上的碱基受到一种称为甲基化的化学修饰，将使其构型转变成Z型。此时螺旋形式转为左旋，与较常见的右旋B型相反40。某些专门与Z-脱氧核糖核酸结合的蛋白质可辨识出这种少见的结构，此外Z型脱氧核糖核酸可能参与了转录作用的调控41。,内 容 概 览,内 容 概 览,内 容 概 览,第一节,第二节,第三节,第四节,第五节,内容,公 司 发 展,交 互 图,饼 图,50%,24%,10%,16%,50%,24%,16%,1

15、0%,AAA,DDD,BBB,CCC,项 目 AB,项目A,项目B,项目内容XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX,项目内容XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX,状 态 图,内容 C,内容 B,内容 A,关 系 图,A结点,D结点,C结点,B结点,A,B,C,D,关系,概 念 图,项 目 图,A,XXXXXXXXXXXXXXXXXXXXXXXXXXX,B,YYYYYYYYYYYYYYYYYYYYYYYY,C,ZZZZZZZZZZZZZZZZZZZZZZZZZZ,B,C,A,影 响 分 析 图,文字内容,影响3,影响2,影响1,图 表,DDD,FFF,EEE,BBB,CCC,AAA,中间,标 题,图 表,AAA,BBB,内容,内容,图 表,ccc,AAA,标题,bbb,aaa,BBB,CCC,项 目 图,项 目 图,总 结,1,2,3,4,5,标题,Thank you！,