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

A hydrogen bond is an intermolecular electrostatic attraction between a hydrogen atom and an electronegative atom with a lone pair of electrons.
In a polar molecule, like hydrogen fluoride or HF, ammonia or NH3, and water or H2O, the fluorine, nitrogen, or oxygen atom is more electronegative than hydrogen.
The more electronegative atom attracts bonding electron pairs more strongly than hydrogen. This results in unequal electron distribution in the bond, giving the electronegative atom a partial negative charge and the hydrogen atom a partial positive charge.
The partial positive charge on the hydrogen atom enables it to attract non-bonded pair of electrons of an electronegative atom in its vicinity, forming a hydrogen bond.
Hydrogen bonds provide structural stability to various biological molecules, including DNA.

hydrogen bonds

A hydrogen bond is formed when a weakly positive hydrogen atom already bonded to one electronegative atom (for example, the oxygen in the water molecule) is attracted to another electronegative atom from another polar molecule, such as water (H2O), hydrogen fluoride (HF), or ammonia (NH3). The huge electronegativity difference between the H atom (2.1) and the atom to which it is bonded (4.0 for an F atom, 3.5 for an O atom, or 3.0 for an N atom), combined with the very small size of an H atom results in unequal distribution of charges between the hydrogen atom and the electronegative atom. This causes the hydrogen atom to become partially positive and the electronegative atom to become partially negative. Thus, molecules with F-H, O-H, or N-H moieties are strongly attracted by similar moieties of nearby molecules and form a particularly strong dipole-dipole attraction called the hydrogen bond.
Hydrogen bonds have a pronounced effect on the properties of liquids and solids. For example, the melting point and boiling point for methylamine (CH3NH2) are greater than ethane (CH3CH3), although both are similar in size and mass. Unlike ethane, methylamine possesses an &#8722;NH group that enables it to form hydrogen bonds and increase the intermolecular forces between molecules, eventually raising its melting and boiling points.
Hydrogen bonding is common in the natural world, such as the DNA that contains genetic information and is found in every organism. Each base pair of DNA is formed by hydrogen bonding via three hydrogen bonds. This complementary base pairing contributes to the shape and stability of the DNA double helical structure.
This text is adapted from <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>&#160;

A hydrogen bond is formed when a weakly positive hydrogen atom already bonded to one electronegative atom (for example, the oxygen in the water molecule) ...

Education

JoVE Core

Anatomy and Physiology

Unit 1

Fundamentals of Chemistry

KEY TERMS AND CONCEPTS

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

SC.912.P.8.1

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SC.912.P.8.2

The Atomic Theory of Matter

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SC.912.P.8.3

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SC.912.P.8.4

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SC.912.P.8.5

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SC.912.P.8.7

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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