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

Wiązanie wodorowe to międzycząsteczkowe przyciąganie elektrostatyczne między atomem wodoru a atomem elektroujemnym z samotną parą elektronów.
W cząsteczce polarnej, takiej jak fluorowodór lub HF, amoniak lub NH3 i woda lubH2O, atom fluoru, azotu lub tlenu jest bardziej elektroujemny niż wodór.
Bardziej elektroujemny atom przyciąga wiążące pary elektronów silniej niż wodór. Powoduje to nierównomierny rozkład elektronów w wiązaniu, dając atomowi elektroujemnemu częściowy ładunek ujemny, a atomowi wodoru częściowy ładunek dodatni.
Częściowy ładunek dodatni na atomie wodoru umożliwia mu przyciąganie w jego pobliżu niezwiązanej pary elektronów atomu elektroujemnego, tworząc wiązanie wodorowe.
Wiązania wodorowe zapewniają stabilność strukturalną różnym cząsteczkom biologicznym, w tym DNA.

wiązania wodorowe

Wiązanie wodorowe powstaje, gdy słabo dodatnio naładowany atom wodoru, już związany z jednym atomem o dużej elektroujemności (na przykład tlenem w cząsteczce wody), przyciąga inny atom o dużej elektroujemności z innej cząsteczki polarnego związku, takiego jak woda (H_2O), fluorowodór (HF) lub amoniak (NH_3). Ogromna różnica elektroujemności między atomem wodoru (2.1) a atomem, z którym jest związany (4.0 dla atomu fluoru, 3.5 dla atomu tlenu lub 3.0 dla atomu azotu), w połączeniu z bardzo małym rozmiarem atomu wodoru, powoduje nierównomierny rozkład ładunków między atomem wodoru a atomem o dużej elektroujemności. To prowadzi do częściowego naładowania dodatnio atomu wodoru i częściowego naładowania ujemnie atomu o dużej elektroujemności. Molekuły zawierające grupy F-H, O-H lub N-H są silnie przyciągane przez podobne grupy sąsiednich cząsteczek i tworzą szczególnie silne oddziaływanie dipol-dipolne, zwane wiązaniem wodorowym.

Wiązania wodorowe mają wyraźny wpływ na właściwości cieczy i ciał stałych. Na przykład temperatura topnienia i wrzenia metyloaminy (CH_3NH_2) jest wyższa niż etanu (CH_3CH_3), mimo że oba związki są podobnej wielkości i masy. W odróżnieniu od etanu, metyloamina posiada grupę -NH, która umożliwia jej tworzenie wiązań wodorowych i zwiększenie sił międzymolekularnych między cząsteczkami, co ostatecznie podnosi jej temperaturę topnienia i wrzenia.

Wiązania wodorowe są powszechne w świecie naturalnym, na przykład w DNA, który zawiera informacje genetyczne i występuje we wszystkich organizmach. Każdy par zasad DNA jest tworzony przez wiązanie wodorowe za pomocą trzech wiązań wodorowych. To komplementarne parowanie zasad przyczynia się do kształtu i stabilności struktury podwójnej helisy DNA.

Ten tekst jest adaptacją z <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>

Wiązania wodorowe

Wiązanie wodorowe powstaje, gdy słabo dodatni atom wodoru jest już związany z jednym atomem elektroujemnym (na przykład tlenem w cząsteczce wody) ...

Education

JoVE Core

Anatomy and Physiology

Anatomia i fizjologia

Unit 1

Jednostka 1

Fundamentals of Chemistry

Podstawy chemii

KEY TERMS AND CONCEPTS

Kluczowe terminy i pojęcia

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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the periodic table and organismal elements

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isotopes and radioisotopes

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introduction to chemical bonds

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ionic bonds

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hydrogen bonds

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...

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colloids and suspensions

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key terms and concepts

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Classifying Matter by State

Chemistry is the study of matter and the changes it undergoes. Matter is anything that has mass and occupies space. Matter is all around us; the air, ...

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Differentiate between physical and chemical properties and physical and chemical changes of matter.

SC.912.P.8.1

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Physical and Chemical Properties of Matter

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SC.912.P.8.2

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The Electromagnetic Spectrum

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Interference and Diffraction

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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

Periodic Classification of the Elements

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Electron Configuration of Multielectron Atoms

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Relate properties of atoms and their position in the periodic table to the arrangement of their electrons.

SC.912.P.8.5

Types of Chemical Bonds

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Ionic Bonding and Electron Transfer

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Intermolecular Forces

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Distinguish between bonding forces holding compounds together and other attractive forces, including hydrogen bonding and van der Waals forces.

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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