Nitrogenous bases connect like puzzle pieces due to their shape

Stacking nucleotide molecules like toy blocks helps build DNA's structure

Each nucleotide is made up of a sugar—deoxyribose—a phosphate group, and one of four bases that contain nitrogen. Like building a two-tone, spiral staircase from the ground up, nucleotides are linked one on top of another so that sugars and phosphates alternate. The twisted strands are held together by hydrogen bonds between base pairs.

DNA's four-letter blueprint makes the variety of all living things possible

The proteins responsible for cellular functions and an organism's traits are built outside of a cell's nucleus from RNA—single-stranded molecules created by reading the information in DNA. DNA's double-stranded structure makes it more stable and allows RNA to be made from either of its complementary strands.

The structure of DNA helices comes in three major varieties

The hereditary molecule can take the form of A-DNA, B-DNA, or Z-DNA based on environmental conditions such as ion concentration and humidity—a characteristic identified by Rosalind Franklin. A-DNA is the shortest and widest of the three, while Z-DNA is the longest and narrowest. B-DNA—the most common variety in living cells—is the intermediate.

Glowing chemicals allow scientists to read DNA like a barcode

The process of determining the order of nitrogenous bases in DNA involves first cutting the DNA into fragments, which are duplicated multiple times using bacteria. Fluorescently labeled terminator bases are added to fragments, which are sorted by length and read via laser to reconstruct the sequence.

Storing data in DNA requires converting binary code into DNA's four-base system

Researchers have suggested that DNA's ability to form compact, dense structures justifies investigating its use for long-term, safe data archiving. This system could fit all of the world's data in a single shoebox, though processing each bit into a nucleotide base takes 2 minutes, as of 2024.

Genes are the basic units of heredity

These segments of DNA—long molecules made of nucleotides that coil into chromosomes—code instructions for making specific proteins, which correspond to different traits. Approximately 98 to 99% of human DNA is non-coding, with functions beyond protein synthesis.

All humans share 99.9% of the same DNA

Of the 3 billion base pairs that make up the human genome—the complete set of genetic material for the species—the diversity of humans is the result of variations in about 3 million molecular bases. The closest nonhuman genetic match is the chimp, with 98.8% similar genetics.

DNA may serve as a flame retardant by self-extinguishing some burning materials

When DNA burns, phosphate groups release phosphoric acid, and nitrogenous bases release ammonia. These molecules, along with the sugar in DNA's backbone, shift the combustion reaction toward the formation of intumescent char. This puffy, carbon-rich layer protects open flames from burning the material beneath.

Watson and Crick revealed DNA's double-helix structure using others' key findings

Their 1953 model, made from cardboard cutouts, explained how DNA stores genetic information through base pairing. Rather than experimenting and collecting their own data, they incorporated patterns and data from other scientists through trial and error.

How chemical bonds between atoms form molecules and large geometric structures

In ionic bonding, one atom transfers at least one electron to another atom, forming two atoms of opposite charge. These atoms attract one another and can stack up in a 3D grid called a lattice. Covalent bonding, where electrons are instead shared, can produce enormous molecules, such as the two found in human chromosome 13, which each contain 37 billion atoms.

Watch how DNA is packaged to a 10,000th of its original size in a cell

In humans, the 2-meter (6.56-foot) molecule wraps around spool-like proteins called histones, forming beads—nucleosomes—that fold up into fibers. These fibers—chromatin—form loops through folding that compress into larger fibers, which tightly coil together to form a chromosome.

How the number of subatomic particles helps identify different types of atoms

Different elements, such as oxygen and nitrogen, can be distinguished by the number of protons in each, since all atoms of the same element have the same number of protons. Isotopes of a given element have the same number of protons but different numbers of neutrons, while ions are atoms possessing different numbers of electrons than protons.

Adhesion molecules and intercellular junctions allow cells to connect together

While some organic structures are mostly composed of non-cellular components (e.g., collagen and calcium phosphate minerals in bones), tissues and organs composed of connected cells rely on specialized proteins and connections to create watertight seals that protect cells within the interior from environmental molecules.

Ancestry testing matches DNA to known genetic variants found in specific ancestries

After a lab receives a person's sample, the DNA is separated into single strands, which are chemically cut into smaller fragments. The fragments are then fed into an array of variants of known origins, and technicians observe if a person's fragments bind to specific variants.

All publicly available DNA sequences are available at GenBank

The National Institutes of Health's database stores comprehensive, annotated DNA sequences as part of the International Nucleotide Sequence Database Collaboration. It encourages unrestricted data access within the scientific community while allowing submitters to retain intellectual property rights over their data.

Different types of ice link water molecules together in unique shapes

The ice used to cool drinks—Iₕ—is composed of H₂O molecules arranged in hexagonal structures. This structure forms as ice expands during freezing, providing additional space between molecules, lowering the overall density, and allowing it to float in water. Under sufficient pressure, this spacing can collapse in many ways, creating new forms of ice.

Gravity, electromagnetism, and two nuclear forces make up nature’s fundamental forces

While gravity is the most familiar force, it is also the weakest and the only one without a particle to mediate the force. The weak nuclear force is responsible for radioactive decay and transmutation of elements, while the strong nuclear force holds quarks together.

Your DNA may determine whether you like coffee or tea

Whether people prefer coffee or tea may boil down to a matter of taste genetics. People with a version of a gene that increases sensitivity to the bitter flavor of caffeine tend to be coffee drinkers, according to a report. Read on for more.

Ammonium may be the sixth basic taste

Researchers have proposed various candidates for the sixth official taste, including "fat." But research published in 2023 posits that ammonium should be considered the sixth taste since they found humans can apparently detect ammonium chloride, which the scientists describe as "bitter, salty, and a little sour." Detecting ammonia could be a survival mechanism to help detect when certain foods, including seafood, are no longer safe to eat. The work hinged on experiments with human cells exposed to ammonium chloride as well as rodent research.

A diamond's color comes from impurities, defects, and unique formation processes

While most diamonds are transparent and sparkly, the presence of nitrogen and boron during formation can make them yellow, orange, or blue. Radiation can produce green diamonds, and structural deformities can introduce red hues.

A fascinating look at why cucumber tendrils coil in opposite directions

The tendrils of cucumber plants coil when they hit a surface, creating a distinct telephone-cord look. Charles Darwin wrote about the mystery in the 1850s, though it wasn't until the 21st century that scientists figured out just how mysterious the coil is: its tendrils coil in opposite directions.

How do 5G base stations work?

5G relies on a combination of base stations, including macrocells, small cells, and femtocells. The differences between the three are apparent in size, coverage, and cost—but, small cells in particular are key to providing the high millimeter wave frequencies 5G promises. Learn more in this three-minute video.

'Gram-negative' bacteria: Bugs with extra defenses along their cell walls

The term 'Gram-negative' bacteria refers to bugs which react a certain way under a Gram stain test. These bacteria are harder to kill due to their double-layer cell walls with a thin peptidoglycan layer in between. This structure makes the delivery of drugs into the bacterial cell substantially more difficult.

Mitochondrial DNA swapping can occur before or after fertilization

Mitochondrial replacement therapy can be conducted with four different techniques, with varying genetic material transferred depending on the approach. Maternal spindle transfer, one common method, involves transplanting the nuclear DNA from a mother into an unfertilized egg from a donor. The donor egg is then fertilized and implanted into the mother's uterus using in vitro fertilization. Another major approach, pronuclear transfer, does the genetic swapping after the mother's egg has already been fertilized. This order of operations may be uncomfortable for some individuals, but the success rate with this technique is higher.

About 99% of Earth's atmosphere is made of nitrogen and oxygen

At 78% and 21% respectively, the two elements are followed by argon with almost 1%. Trace amounts of other molecules, including greenhouse gases such as methane and carbon dioxide, and particulate matter such as dust and pollen, make up the remainder of the atmosphere's contents.

While atoms are normally made of protons, neutrons, and electrons, exotic ones have been built with antimatter—alternate versions of normal matter that live for fractions of a second and are about a billion times as rare.

Visualize how CRISPR-Cas9—a type of immune system used by single-celled organisms to attack invasive viruses—targets and makes precise changes to a gene's DNA.

Pure water does not conduct electricity because this flow of energy requires the movement of charged particles, and water is a neutral molecule.

As of 2025, the most cited papers in science include a review of graphene, methods to improve image recognition, streamlining electron density calculations, and optimizing protein studies.

The Nasdaq's 'Magnificent 7' companies are responsible for roughly 40% of the Nasdaq 100 index's gains, while the remaining 93 companies account for the other 60%.

The Great Salt Lake's distinct dual coloration results from high-salinity organisms that only live in the northern portion and produce a purple protein.

Some coin denominations have ridges etched on their sides, partly to prevent counterfeiting, in a practice called 'reeding.'

Meet the 56 signers of the Declaration of Independence—most of whom didn't put pen to paper until August 2, 1776—and see their original signatures.

The United States is one of only around two dozen countries with a fully federal system of government, in which power is divided between national and state governments.

While the sun's gravity keeps the planets in orbit, their gravity also pulls on the sun, causing it and everything else in the solar system to orbit around a mutual balance point called the barycenter—the true center of the solar system.

When you complete a CAPTCHA on a website to prove you are human, you may be unknowingly training algorithms for self-driving cars, whose systems require training data to help identify crosswalks, bicycles, and other outdoor objects.

Power lines are dotted with large, brightly colored balls to improve the visibility of these thin wires to helicopters and small planes and help prevent potential crashes.

Ebola is a filovirus, meaning it resembles a thread under a microscope, though it sometimes twists and can resemble a bowl of spaghetti.

Budweiser stores yeast derived from the original 1800s strain in a secret bunker, which only the Head of Yeast Management can access—not even the CEO

The syncytiotrophoblast is the outer layer of the placenta and the largest human cell, spanning an area about twice that of a king-sized bedsheet.

Sony set the standard for cylinder-shaped batteries when it repurposed manufacturing equipment used to make rolls of magnetic recording tape.

Some Pokémon have been named after real and fictional organisms, while some real-world species have been named after Pokémon, such as Chilicola charizard and Binburrum zapdos.

To reduce wrinkles in clothing, research recommends gentle wash cycles with more water and tumble drying with smaller loads and longer times.

Prince's sexually explicit 1984 track 'Darling Nikki' attracted the ire of the Parents Music Resource Center, an advocacy group that inspired the Parental Advisory sticker, even though the song ends with a Christian message.

Researchers believe the brain consolidates memories, processes emotions, and plans for the future during dream states

Search a massive database of over 4 decades of clues from the TV quiz show 'Jeopardy!'

Scientists can determine Earth's past climate conditions by analyzing air trapped in microscopic bubbles within ice cores—columns of compressed snow layers that build up over hundreds of thousands of years.

The most expensive ad of all time was for Chanel No. 5 perfume and cost roughly $33M to produce in 2004—about $57M in today's dollars.

For centuries, Niagara Falls has been a magnet for daredevils seeking to conquer one of nature's most powerful wonders, with its 200-foot drop and water rushing at 32 feet per second with 280 tons of force.

The Brothers Grimm were lawyers before they were storytellers, and became interested in fairy tales as they began investigating how rules and customs had been passed down through cultures.