Name: hydrogen bonding and dna stability
Uploaded: 2025-05-22T09:05:54.000Z
Duration: 1 min 4 s
Channel: JoVE

K12 Standards

Florida Department of Education

High School

Physical Science

SC.912.P.8

SC.912.P.8.6

Hydrogen Bonds

氢键是一种分子间静电吸引力，发生在氢原子与带有孤对电子的电负性原子之间。
在极性分子中，例如氟化氢（HF）、氨（NH3）和水（H2O），氟、氮或氧原子比氢原子更具电负性。
电负性较强的原子比氢原子更强烈地吸引共用电子对。这导致化学键中的电子分布不均，使电负性原子带有部分负电荷，而氢原子带有部分正电荷。
氢原子上的部分正电荷使其能够吸引附近电负性原子的未共用电子对，从而形成氢键。
氢键为包括 DNA 在内的多种生物分子提供结构稳定性。

氢键

氢键形成于一个弱正氢原子与一个带负电的原子进行结合（例如，水分子中的氧原子）时被另一个极性分子的另一个电负原子所吸引，例如水（H2O）、氟化氢（HF）或氨（NH3）。H原子（2.1）和与之结合的原子（F原子为4.0，O原子为3.5，或N原子为3.0）之间有着巨大负电荷的差异，以及H原子非常小的尺寸，导致氢原子和电负原子之间的电荷分布不均匀。这导致氢原子部分带有正电荷，而电负原子则部分带负电荷。因此，具有F-H、O-H或N-H基团的分子会被附近分子中类似的基团强烈吸引，并形成一种特别强的偶极—偶极之间的相互作用，称为氢键。

氢键对液体和固体的性质有着显著的影响。例如，甲胺（CH3NH2）的熔点和沸点高于乙烷（CH3CH3），尽管两者在大小和质量上相似。与乙烷不同，甲胺具有一个能够形成氢键并增强分子间力的−NH基团，最终将能够提高其熔点和沸点。

氢键在自然界中很常见，例如DNA中含有遗传信息，并存在于每个有机体中。DNA的每个碱基对通过三个氢键进行氢键配对。这种互补碱基的配对有助于增强DNA双螺旋结构的形状和稳定性。

本文改编自 <a href="https://openstax.org/books/anatomy-and-physiology-2e/pages/">Openstax, Anatomy and Physiology 2e, Section 2.2: Chemical Bonds</a> and <a href="https://openstax.org/books/anatomy-and-physiology-2e/pages/">Openstax, Chemistry 2e, Section 10.1: Intermolecular Forces </a>

当一个带弱正电的氢原子与一个电负性原子（例如水分子中的氧原子）成键后，又与另一个电负性原子之间形成一种相互作用时，便形成氢键。

Education

教育

JoVE Core

Anatomy and Physiology

解剖学与生理学

Unit 1

第 1 单元

Fundamentals of Chemistry

化学基础

KEY TERMS AND CONCEPTS

关键术语与概念

hydrogen bonding and dna stability

Hydrogen bonding helps explain why some molecules stick together more strongly than others. A hydrogen bond forms when a weakly positive hydrogen atom, already bonded to an electronegative atom, is attracted to another electronegative atom on a nearby polar molecule. Common examples include water, hydrogen fluoride, and ammonia.

This attraction happens because hydrogen has a much lower electronegativity than atoms such as fluorine, oxygen, and nitrogen. The electronegativity difference, along with hydrogen’s very small size, creates an uneven charge. The hydrogen becomes partially positive, and the electronegative atom becomes partially negative. Molecules with F-H, O-H, or N-H groups can then form a strong dipole-dipole attraction called a hydrogen bond.

Hydrogen bonding can change the properties of liquids and solids. For example, methylamine has a higher melting point and boiling point than ethane, even though the two molecules are similar in size and mass. The difference is that methylamine has an -NH group, which lets it form hydrogen bonds and strengthens the intermolecular forces between its molecules.

Hydrogen bonds are also important in living things. DNA, which carries genetic information in every organism, relies on hydrogen bonding between base pairs. Each base pair is held together by three hydrogen bonds. This complementary pairing helps give DNA its double helix shape and supports its stability.

Hydrogen Bonding and DNA Stability

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key terms and concepts

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SC.912.P.8.1

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Physical and Chemical Properties of Matter

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Phase Diagrams

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SC.912.P.8.2

The Atomic Theory of Matter

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Subatomic Particles

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SC.912.P.8.3

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Ions and Ionic Charges

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SC.912.P.8.4

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SC.912.P.8.5

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A. A working definition of matter is that it takes up space, has mass, and has measurable properties. Matter is comprised of atomic, subatomic, and elementary particles.

B. Electrons are key to defining chemical and some physical properties, reactivity, and molecular structures. Repeating (periodic) patterns of physical and chemical properties occur among elements that define groups of elements with similar properties. The periodic table displays the repeating patterns, which are related to the atom's outermost electrons. Atoms bond with each other to form compounds.

C. In a chemical reaction, one or more reactants are transformed into one or more new products. Many factors shape the nature of products and the rates of reaction. 

D. Carbon-based compounds are building-blocks of known life forms on earth and numerous useful natural and synthetic products.

Hydrogen Bonding and DNA Stability

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