相关实验视频
Updated: Jun 5, 2026

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Preparation of DNA-crosslinked Polyacrylamide Hydrogels
Published on: August 27, 2014
在65 pN时过度拉伸DNA不需要从自由端或口剥离
D Hern Paik1, Thomas T Perkins
1JILA, National Institute of Standards and Technology, and University of Colorado, Boulder, Colorado 80309, USA.
Journal of the American Chemical Society
|January 7, 2011
概括
过度拉伸的DNA机制在一项新的测试中得到了研究. 在DNA过度伸展中的歇斯底里是的结果,而不是过渡的要求.
科学领域:
- 分子生物学分子生物学
- 生物物理学的生物物理.
- 材料科学 材料科学 材料科学
背景情况:
- 在大约65 pN时,DNA表现出显著的机械过渡,称为过度拉伸,大约65 pN.
- 这种过度紧张状态的确切机制和性质仍然是科学文献中争论的主题.
- 现有的模型通常涉及过渡过程中单链DNA (ssDNA) 的形成.
研究的目的:
- 研究DNA拓和完整性在过度伸展过渡中的作用.
- 要确定ssDNA的形成是DNA过度伸展的先决条件还是后果.
- 为了阐明DNA强力延伸曲线中的歇斯底里斯的起源.
主要方法:
- 开发一种拓上封闭的,旋转上不受约束的DNA测定.
- 使用原子力显微镜或光学子来施加力并测量DNA扩展.
- 将受控的入DNA中,观察它们对过度伸展过渡和歇斯底里作用.
- 在5μm/s的收缩速度下,测量带有或没有的DNA力延伸曲线.
主要成果:
- 封闭式,无测定中的DNA显示了在65 pN的规范过伸过渡,没有歇斯底里.
- 引入单个引发了强力延伸曲线中的歇斯底里.
- 的数量增加与更高程度的歇斯底里相关.
- 过度伸展的过渡本身不需要先前存在的或自由端.
结论:
- 对于DNA过度伸展来说,ssDNA的生成不是一个强制性的步骤.
- 在DNA过度伸展中观察到的歇斯底里症是DNA损伤的结果,例如,而不是过渡的内在性质.
- 这一发现澄清了完整的DNA的机械行为以及实验研究中观察到的歇斯底里症的因素.
相关概念视频
Nucleotide Excision Repair
Overview
Nucleotide Excision Repair
DNA Distortion and Damage
Cells are regularly exposed to mutagens—factors in the environment that can damage DNA and generate mutations. UV radiation is one of the most common mutagens and is estimated to introduce a significant number of changes in DNA. These include bends or kinks in the structure, which can block DNA replication or transcription. If these errors are not fixed, the damage can cause mutations, which in turn can result in cancer or disease depending on which sequences are...
Cells are regularly exposed to mutagens—factors in the environment that can damage DNA and generate mutations. UV radiation is one of the most common mutagens and is estimated to introduce a significant number of changes in DNA. These include bends or kinks in the structure, which can block DNA replication or transcription. If these errors are not fixed, the damage can cause mutations, which in turn can result in cancer or disease depending on which sequences are...
Homologous Recombination
The basic reaction of homologous recombination (HR) involves two chromatids that contain DNA sequences sharing a significant stretch of identity. One of these sequences uses a strand from another as a template to synthesize DNA in an enzyme-catalyzed reaction. The final product is a novel amalgamation of the two substrates. To ensure an accurate recombination of sequences, HR is restricted to the S and G2 phases of the cell cycle. At these stages, the DNA has been replicated already and the...
Fixing Double-strand Breaks
The double-stranded structure of DNA has two major advantages. First, it serves as a safe repository of genetic information where one strand serves as the back-up in case the other strand is damaged. Second, the double-helical structure can be wrapped around proteins called histones to form nucleosomes, which can then be tightly wound to form chromosomes. This way, DNA chains up to 2 inches long can be contained within microscopic structures in a cell. A double-stranded break not only damages...
Fixing Double-strand Breaks
The double-stranded structure of DNA has two major advantages. First, it serves as a safe repository of genetic information where one strand serves as the back-up in case the other strand is damaged. Second, the double-helical structure can be wrapped around proteins called histones to form nucleosomes, which can then be tightly wound to form chromosomes. This way, DNA chains up to 2 inches long can be contained within microscopic structures in a cell. A double-stranded break not only damages...
Base Excision Repair
One of the common DNA damages is the chemical alteration of single bases by alkylation, oxidation, or deamination. The altered bases cause mispairing and strand breakage during replication. This type of damage causes minimal change to the DNA double helix structure and can be repaired by the base excision repair (BER) pathways. BER corrects damaged DNA sequences by removing the damaged base and restoring the original base sequence using the complementary strand as a template.
The first step of...
The first step of...

