网页2000年1月7日 — These enzymes are called DNA topoisomerases. In addition to the requirement to unwind DNA for replication and for transcription, there is an absolute requirement for the correct topological tension in the DNA (super-helical density) in order for genes to be regulated and expressed normally.
网页Best source: Bates and Maxwell, “DNA Topology”. Helical nature of DNA has profound implications: DNA being long, stiff, and helical means that there is potential for long-range communication between sites but also long-range interference between processes. DNA transcription, replication, and recombination all are affected by:
DNA Topology - YouTube
网页2016年5月25日 — Copyright MIT, all rights reserved. An exploration of the complicated world of DNA topology: how DNA is described with linking number, twist, and writhe, and how topoisomerases and gyrases...
1.6: DNA Supercoiling and Topoisomerases - Biology LibreTexts
网页The topology of DNA can be described by three parameters: Linking Number (L) An integer value. "Positive" is referenced as right-handed. Twist (T) A real number (the "apparent" linkage number) Writhe (W) A real number ("supercoils" in the DNA structure) Consider closed circular DNA: Linking number is an integer value.
Introduction to DNA Topology - SpringerLink
网页2013年10月10日 — In this expository chapter we give an elementary introduction to DNA and to proteins that can knot and link circular DNA, with a special focus on recombination. We also describe the Ernst and Sumners tangle model of the action of proteins on circular DNA. Download chapter PDF.
Nucleic acid structure - Wikipedia
网页Nucleic acid structure refers to the structure of nucleic acids such as DNA and RNA. Chemically speaking, DNA and RNA are very similar. Nucleic acid structure is often divided into four different levels: primary, secondary, tertiary, and quaternary.
DNA Topology and Topoisomerases - SpringerLink
网页2018年1月1日 — This entry will discuss biological and mathematical aspects of DNA topology and compare and contrast the reactions catalyzed by individual classes and subclasses of topoisomerases. Finally, it will describe how the reaction mechanisms of the different topoisomerases dictate their cellular functions.
9.1: The Structure of DNA - Biology LibreTexts
网页2022年3月17日 — The DNA molecule is a polymer of nucleotides. Each nucleotide is composed of a nitrogenous base, a five-carbon sugar (deoxyribose), and a phosphate group. There are four nitrogenous bases in DNA, two …
THE TOPOLOGY OF DNA | Calculating the Secrets of Life: …
网页Chapter 6 describes aspects of the geometry and topology of DNA and points out various topological transformations that must be performed on DNA by enzymes in order to carry out the life cycle of the cell.
DNA GEOMETRY AND TOPOLOGY: LINKING, TWISTING, AND …
网页WINDING THE DOUBLE HELIX: USING GEOMETRY, TOPOLOGY, AND MECHANICS OF DNA 155 introduces the concepts necessary to describe the mechanical equilibria of closed circular DNA and gives an analysis of transitions of superhelical transitions, dealing specifically with strand separation.