​This glossary provides pronunciations and easy-to-understand definitions for terms commonly used in basic biomedical research. To search the glossary, enter the word​ or term you’re looking for and the terms and definitions containing the word(s) will appear below. Search results are refined with each letter entered.​ ​You can also use your browser’s “find” feature.


The region on an enzyme's surface where only a specific substrate can bind, resulting in a che​mical reaction.​​​​​

An acronym describing pharmacokinetic processes that pharmacologists study regarding drugs in the body: absorption, distribution, metabolism (break down), and excretion​. Sometimes, toxicity is included in this list through the acronyms ADMET or ADME-Tox.​

For more, check out our Biomedical Beat​ blog post: What Happens to Medicine in Your Body?​​

(AG-uh-nist) A molecule that binds to a receptor in a cell to trigger a response, such as mu​scle contraction or hormone release.​​

For more, check out our Biomedical Beat​ blog post: How Do Medicines Work?

(uh-MEE-no) A chemical building block of proteins. There are 20 standard amino acids, each of which has the same basic structure with a different side chain. The side chain gives the amino acid its unique properties.​​

(an-l-JEE-zik) An agent or drug that reduces pain without affecting consciousness.​

(an-uhs-THEE-zhuh) Anesthesia is a medical treatment that prevents patients from feeling pain during procedures like surgery, certain screening and diagnostic tests, tissue sample removal (e.g., skin biopsies), and dental work.​

For more, check out our anesthesia featured topics page.

Anesthesiologists are doctors specializing in the field of anesthesiology. They administer anesthetics and carefully monitor patients throughout surgery and during recovery.​

(an-uhs-thee-zee-OL-uh-jee) The medical field related to using anesthetic drugs to prevent patients from feeling pain during surgery. Doctors in this field, called anesthesiologists, carefully monitor patients throughout surgery and during recovery.​

An anesthetic is a medicine used to prevent pain during procedures like surgery and dental work.​​

For more on anesthesia, check out our featured topics page.

When a cell has the wrong number of chromosomes, either more or less than it should.

(an-TAG-uh-nist) A molecule that binds to a receptor in a cell to prevent a response, such as a muscle contraction or hormone release. For example, some medicines to treat opioid addiction bind to opioid receptors, blocking heroin or other opioids from activating them.​

For more, check out our Biomedical Beat blog post: ​In Other Words: Some Antagonists Are Heroes

A medicine that can kill bacteria or keep them from growing.​

For more, check out our Biomedical Beat​ blog post: What Is Antibiotic Resistance?

When bacteria change in ways that make antibiotic medicines ineffective.​​​​

For more, check out our Biomedical Beat​ blog post: What Is Antibiotic Resistance?

A protein the immune system produces in response to a foreign substance such as a virus or bacterium.​​​

T​he parts of an infectious organism that the immune system recognizes are foreign to the human body.​

A drug that reduces inflammation.​​

A substance that kills microorganisms such as bacteria or mold, or stops them from growing and causing disease.​

(an-tee-OCK-si-duhnt) A natural or human-made substance that may prevent or delay some types of cell damage. The body and many foods, including fruits and vegetables, naturally produce antioxidants.

For more, check out our Biomedical Beat blog post: Science Snippet: Antioxidants Explained​

(ap-uhp-TOH-sis) A process in which cells in the body die in a controlled and predictable way because they have DNA damage or are not needed. One other type of cell death is necrosis.​​

For more, check out our Biomedical Beat blog post: Science Snippet: Apoptosis Explained

A feature where machines learn to perform tasks, rather than simply carrying out computations that are input by human users. Early applications of AI included machines that could play games such as checkers and chess, and programs that could reproduce language.​​​

A fundamental unit of matter, the substance a physical object is composed of, consisting of a nucleus and electrons.​

(ah-DEH-no-seen try-FOSS-fate)The major source of energy for biochemical reactions in all organisms. ATP is formed when animals digest food or plants undergo photosynthesis. Energy is released when certain chemical bonds in ATP are broken.

For more, check out our Biomedical Beat blog post: ​Science Snippet: ATP's Amazing Power

(aw-TAH-fuh-jee) A natural breakdown-recycle process within a cell. The cell breaks down and destroys old, damaged, or abnormal proteins and other substances within its cytoplasm, including bacteria and viruses. It then recycles them for important cellular functions.


(bak-TEER-ee-uhm) (plural: bacteria) A one-celled microorganism without a nucleus. Bacteria live almost everywhere in the environment. Some bacteria may infect humans, plants, or animals. They may be harmless, or they may cause disease. Scientists often use bacteria as research organisms to stu​dy basic biological processes.​

How quickly and to what extent the active part of a drug is absorbed by the body and is available at the site where it’s needed.​​​

For more, check out our Biomedical Beat blog post: What Happens to Medicine in Your Body?

The scientific study of the chemistry of living cells, tissues, organs, and organisms.​​​

Capable of being broken down physically and/or chemically by microorganisms.​​

A highly organized community of microorganisms that develops naturally on certain surfaces. Biofilms can be helpful in treatment of wastewater, for example. But they can also be harmful, like when they form on medical devices implanted in people. These biofilms are highly resistant to antibiotic medicines.

For more, check out our Biomedical Beat blog post: Science Snippet: Brush Up on Biofilms

A field of research that relies on computers to store and analyze large amounts of biological data.​​​

An organism’s innate timing device. Composed of proteins that interact in cells throughout the body, these clocks produce circadian rhythms and regulate their timing.​​

For more, check out our Biomedical Beat blog post: Why Am I So Tired?

A natural or synthetic material introduced into living tissue, often as part of a medical device such as an artificial joint.

The application of fundamental theories and analytical practices to the fields of medicine and biology. Examples include the design and production of artificial limbs and medical implants. Also called bioengineering.​

The science of applying the theories and methods of physics to understand how biological systems work.​

A system or device that converts a biological response into an electrical signal. For example, in a blood glucose monitor, a test strip contains an enzyme that reacts to glucose in the blood, creating an electrical signal that indicates the amount of glucose in the blood. People use biosensors in many fields, including food processing, medicine, and defense.

The use of living organisms or biological systems to make useful products and processes.​​

(bla-STEE-muh) A specialized bud of cells that rapidly divide to form skin, scales, mus​cle, bone, or cartilage needed to create a lost limb, fin, or tail in animals such as lobsters, catfish, and lizards.​​​​

Tissue damage caused by heat, chemicals, electricity, sunlight, or nuclear radiation. Burns are defined by how deep they are and how large an area they cover. Types of burns include:
  • First degree: Damage only to the outer layer of skin (epidermis)
  • Second degree: Damage to the outer layer and the layer beneath it (dermis)
  • Third degree: Damage or complete destruction of both layers of skin
  • Fourth degree: Extends into fat
  • Fifth degree: Extends into muscle
  • Sixth degree: Extends to bone​​


A chemical compound made up of only carbon, hydrogen, and oxygen, usually in the ratio 1:2:1. Carbohydrates include simple sugars like glucose and short and long chains, or polymers, of sugars bound together.

(kahr-SIN-uh-jen) Any substance that causes cancer.​​​​

(KAT-uh-list) A substance that speeds up a chemical reaction that would have occurred without help, but at a much slower rate. Enzymes are biological catalysts.

The basic subunit of any living organism; the simplest form of life. Cells house the biological machinery that makes the proteins, chemicals, and signals responsible for everything that happens inside the body.​​​

The growth of microorganisms, such as bacteria or yeast, or animal or plant cells in the laboratory under controlled, artificial environments. Cell cultures are useful tools that scientists use for biomedical research or to diagnose infections.​

For more, check out our Biomedical Beat blog post: In Other Words: Not All Cultures Are Human

The steps of a cell copying its contents and dividing in two.
  1. Prophase (PRO-faze): Chromosomes condense and become visible and the spindle forms. The spindle is a football-shaped array of fibers made of microtubules and associated proteins. Some of the fibers attach to the chromosomes and help draw them to opposite ends of the cell.
  2. Prometaphase (pro-MET-uh-faze): The nuclear membrane breaks apart, and the spindle starts to interact with chromosomes.
  3. Metaphase (MET-uh-faze): Copied chromosomes align in the middle of the spindle.
  4. Anaphase (ANN-uh-faze): Chromosomes separate into two genetically identical groups and move to opposite ends of the spindle.
  5. Telophase (TEE-lo-faze): Nuclear membranes form around each of the two sets of chromosomes, the chromosomes begin to spread out, and the spindle begins to break down.
  6. Cytokinesis (SY-toh-kin-EE-sis): The cell splits into two daughter cells.
Interphase (IN-tur-faze) is the period in a cell's life cycle when it is not undergoing cell division. There are several checkpoints where the cycle can pause if there’s a problem, such as incomplete DNA synthesis or damaged DNA.​

For more, check out our Biomedical Beat blog post: ​Make Like a Cell and Split: Comparing Mitosis and Meiosis

The brain and spinal cord, which control all the workings of the body.​​

A hollow or pore-containing protein that spans a cell membrane and allows small molecules, such as charged particles (ions), to move from one side of the membrane to the other.​​

A protein that helps other proteins fold or move throughout the cell.​​​

A field that blends chemistry and biology and involves the application of chemical techniques and tools to the study of biological systems.​

A physical force holding atoms together to form a molecule.
  • Covalent bonds form when electrons travel between the atoms' nuclei and are thus “shared.” Molecules can contain single, double, and triple covalent bonds.
  • Peptide bonds are specific covalent bonds formed by joining two amino acids.
  • Ionic bonds are forces that hold together two ions.
  • Metallic bonds are forces that hold atoms together in a metallic substance where electrons continually move from one atom to another and are not associated with any specific pair of atoms.

A collection of chemicals that are stored along with related information, such as the chemical structure, purity, quantity, and other characteristics of the substance.​

The use of computer and information technologies to study problems in chemistry.

A field of study concerned with the composition, properties, and reactions of substances.​

(kee-moh-TAK-sis) The movement of a cell toward or away from a chemical force.

Asymmetric so that the structure and its mirror image are not superimposable (identically matched when laid on top of one another). Organic molecules often have chiral carbons, where four different groups are attached to a single carbon atom​. Molecules can have multiple chiral centers.

A waxy lipid produced by animal cells that is a major component of cell membranes and a building block for some hormones. Cholesterol is also found in foods from animal sources. Good cholesterol carries cholesterol from other parts of your body back to your liver where it can be removed. Bad cholesterol can build up in the arteries, causing them to narrow or become blocked.​

(KROH-muh-tin)The part of the nucleus that consists of DNA and proteins and forms chromosomes.

(KROH-muh-sohm) A cellular structure in the nucleus containing genes. Chromosomes are composed of DNA and proteins, called histones, and they split into two identical strands, called chromatids, during cell division. Humans have 23 pairs of chromosomes, which are present in almost every cell in their bodies. Usually, one chromosome of each pair is from each parent.​

(SIL-ee-uhm) (plural: cilia) A hairlike projection from a cell surface. The rhythmic beating of cilia can move fluid or mucus over a cell or can allow single-celled organisms to move. Cilia are shorter than flagella.​

(sur-KAY-dee-uhn) Pertaining to a period of about 24 hours; applied especially to rhythmic biological repetition like the sleep-wake cycle and the release of some hormones, called circadian rhythms.

For more, check out our circadian rhythms featured topics page.

A scientific study of an intervention in people. The intervention can be a medication, medical device, procedure, or change in behavior. The goal is to find out if the intervention is safe and effective.​

A healthcare professional who provides care for patients.​

In genetics, the process of making many identical copies of a gene or a whole organism. The term also refers to the isolation and manipulation of a gene.

A helper molecule (either inorganic, such as a metal ion, or organic, such as a vitamin) an enzyme needs to work.

The random assembly of various chemical units into chemical libraries of new synthetic compounds.​

(juh-NOH-miks) The study of human genetics by comparisons with other organisms' genetics.​

(kuhm-PEN-suh-tawr-ee hahy-PUR-truh-fee) In humans and some other animals, when part of an organ is removed or destroyed, the remaining portion grows to allow the organ to function as it did before. The liver can regrow to its original size. A kidney, pancreas, thyroid, adrenal gland, or lung can undergo the same process, but in a more limited way. This is one type of regeneration.​

A field of science that uses computers to study complex biological processes that involve many molecular interactions.​

(kon-FOH-kuhl LAY-zur SKAN-ing) A technique for light microscopy that uses a very narrow beam of light (made by the laser) to create images of 3D structures at the cell or tissue level. The narrow beam is forced through a pinhole to keep out-of-focus light from reaching the sample, which increases the resolution without blurriness. Mirrors move to reflect the beam and guide it across the sample (scanning). This technique can visualize structures at different depths in the sample.​​

An immune system in bacteria that recognizes and destroys invading DNA and maybe RNA. It’s been adapted into a gene-editing tool widely used in basic and applied research.​

For more, check out our Biomedical Beat blog post: Q&A With Nobel Laureate and CRISPR Scientist Jennifer Doudna

A process that occurs during meiosis, in which chromosome partners, one inherited from each parent, physically swap sections with one another. This creates hybrid chromosomes that are a patchwork of the original pair. Crossing over occurs in species that reproduce sexually and increases the genetic variety of offspring.

A type of transmission electron microscopy (TEM) where scientists freeze a biological sample so quickly that water molecules don’t have time to form ice crystals. This keeps cellular materials in their normal place. Cold samples are more stable and can be imaged many times.​

​Matter composed of atoms, ions, or molecules packed in a well-organized, repeating grid pattern.​​

(sahy-KLOH-sis) Movement of nutrients and organelles within cells to carry out various cellular functions. The cytoplasm within the cell creates a directional flow that pushes around the content of the cells.

(SAHY-tuh-PLAZ-uhm) The material found between the cell membrane and the nuclear envelope. It includes the cytosol and all organelles except the nucleus.

(SAHY-toh-SKEL-uh-tuhn) A collection of fibers that gives a cell shape and support and allows movement within the cell and, in some cases, by the entire cell. The three main types of cytoskeletal fibers are actin filaments, intermediate filaments, and microtubules.
  • Actin filaments (AK-tin FIL-uh-muhnt) Fibers that contract or lengthen to give cells the flexibility to move and change shape. Together with the protein myosin, actin filaments are responsible for muscle contraction.
  • Intermediate filaments Fibers that provide strength in things like nails, hair, the outer layer of skin, nerves, and certain organs.
  • Microtubules (MY-kroh-TOO-byool) Strong, hollow fibers that act as a structural support for the cell. During cell division, microtubules form the spindle that directs chromosomes to the daughter cells. Microtubules also serve as tracks for transporting vesicles and give structure to flagella and cilia.
For more, check out our Biomedical Beat blog post: Science Snippet: Learn About the Cytoskeleton

(SAHY-tuh-sol) The semi-fluid portion of the cytoplasm, excluding the organelles. The cytosol is a concentrated solution of proteins, salts, and other molecules.​


(dif-uh-ren-shee-AY-shuhn) When an unspecialized cell becomes a specialized cell with a specific function. During development, embryonic stem cells differentiate into the many cell types that make up the human body. Adult stem cells differentiate into the type of tissue in which they are located to replace cells lost to age, disease, or injury.​

(DIP-loyd) A cell or organism that has paired chromosomes, one from each parent.​

Using a network of hundreds or thousands of computers to perform complex calculations that usually can’t be done on a single computer. For example, researchers have used distributed computing to study the dynamics of how proteins fold.​

(dee-AWK-see-RAHY-boh-noo-CLAY-ik) The substance of heredity. A long, usually double-stranded chain of nucleotides that carries the information needed for all cellular functions, including protein production.​

(POL-uh-muh-rays) An enzyme that copies, and sometimes repairs, DNA.​

(SEE-kwuhn-sing) Sometimes called gene or genome sequencing, a lab technique used to find the exact order of the bases in a DNA molecule. The DNA sequence carries information a cell needs to make proteins and RNA molecules.

A chemical or biological molecule that is not found naturally in the body. Medicines are specific types of regulated drugs. The term drug can also refer to drugs of abuse—substances that may or may not be medicines that people use to alter their mental or physical states.​​​

For more, check out our Biomedical Beat blog post: What Is Pharmacology?

The process of giving a drug to a person or animal. Two main components of drug delivery are drug delivery systems and route of administration.
  • Drug delivery systems: Engineered technologies for the targeted delivery and/or controlled release of drugs. Some examples include nanoparticles, liposomes, or other formulations that improve the drug’s ADME properties.
  • Route of administration describes the method used to give the drug to the person or animal. Drugs can be given by mouth (oral); through the skin (topical), mucous membranes (nasal), or lungs (inhaled); or into a vein through a needle (intravenous).


The study of the interrelationship of organisms and their environments, including their habitats, energy sources, nutrients, and other resources.

(ih-DEE-muh) Swelling caused by fluid ​in the body's tissues. It usually occurs in the feet, ankles, and legs, but it can involve the entire body.​

(ih-LEK-truh-lahyt) A mineral in the body that has an electric charge. Electrolytes help balance the amount of water in the body and the pH (acid/base) level; move nutrients into and wastes out of cells and make sure nerves, muscles, the heart, and the brain work the way they should. Electrolytes include sodium, calcium, potassium, chlorine, phosphate, and magnesium.​

(ih-LEK-troh-mag-NET-ik ray-dee-AY-shuhn) Energy produced in the form of a wave. It includes all kinds of radiation, including, in order of increasing energy: radio waves, microwaves, infrared radiation (heat), visible light, ultraviolet radiation (the part of sunlight that causes sunburn), X-rays, and gamma radiation (made by nuclear reactions).

A very small particle that has a negative charge of electricity and travels around the nucleus of an atom​.​​

A technique that uses beams of fast-moving electrons instead of light to magnify samples. Powerful magnets focus the electrons into an image.​​

​A pure substance that can't be chemically separated into simpler substances. Carbon, hydrogen, and oxygen are fundamental elements in biology.​​​​

For more, check out our Biomedical Beat blog posts on elements.

(en-doh-sahy-TOH-sis) A process cells use to absorb nutrients, fluids, proteins, and other molecules. The cell membrane curves inward, encircling the material, then pinches off, producing a vesicle inside the cell.​​

(en-DAH-jeh-nuhs) Produced inside an organism or cell. The opposite is external (exogenous) production.​

For more, check out our Biomedical Beat blog post: How Do Medicines Work?

(EN-doh-plaz-mik reh-TIK-yuh-luhm) An organelle made up of interconnected tubes and flattened sacs. There are two kinds of ER: rough (because it is dotted with ribosomes) ER, which processes newly made proteins​, and smooth ER, which helps make lipids and neutralize toxins.​

(EN-zahym) A biological catalyst that is almost always a protein and speeds up the rate of a specific chemical reaction in the cell by reducing the amount of energy needed for the reaction to proceed​.

For more, check out our Biomedical Beat blog post: ​Dairy Deconstructor: How an Enzyme Enables Milk Digestion

(ep-ih-juh-NET-iks) The study of changes in gene expression or phenotypes that are not the result of changes in DNA sequence.

(yoo-KAYR-ee-ah-tik) A cell with a membrane-bound nucleus and other organelles not found in prokaryotic cells. Eukaryotic cells make up animals, plants, fungi, and some single-celled organisms.

The process by which an organism's genome changes and gives rise to a beneficial trait that allows it to be better adapted to its surroundings. The best-adapted individuals in a population will have the fittest offspring. Over many generations, members of the species with the beneficial trait may take on new roles and may evolve into a new species.​

(ek-soh-sahy-TOH-sis) A process cells use to dump wastes outside of the cell via vesicles.

(ek-struh-SEL-yuh-ler MEY-triks) The material around, within, and between the body's organs, tissues, and cells. In some tissues, it's a thin layer separating cells. In others, it's the major component. The extracellular matrix is most prevalent in connective tissue, the material that forms our skeletons, cushions our internal organs, and winds between blood vessels and around nerves.​


(fluh-JEL-uhm) (plural: flagella) A long, tail-like structure extending from a cell. Sperm and many microorganisms move using flagella.

(floh-RES-uhns) Giving off light at one wavelength (emission) after absorbing light of a different wavelength (excitation). Researchers use fluorescent dyes to take images of cells.​

(plural: fungi) A plantlike, eukaryotic organism that does not make chlorophyll. Examples include mushrooms, yeasts​, and molds. Fungi live throughout the environment and in the human body. Some types of fungi can cause disease.


A protein located inside the cell membrane that helps transmit signals from hormones into cells.​

A unit of heredity; a segment of DNA that contains the code for making a specific protein or RNA molecule.​

When the information in a gene directs the building of a protein. The cell reads the gene in groups of three nucleotides. Each of these groups corresponds to one of 20 different amino acids used to build the protein.​

For more, check out our Biomedical Beat blog post: In Other Words: How Cells Express Themselves

The instructions in a gene that tell the cell how to make a specific protein.

​The manipulation of an organism's genes—introducing, eliminating, or changing them—using modern molecular biology techniques.

The scientific study of genes and heredity—of how certain qualities or traits are passed from parents to offspring as a result of changes in DNA sequence.

(JEE-nohm) All of an organism's genetic material.

(jee-NOHM-iks) The study of all of an organism's genetic material.​

(JEE-nuh-tahyp): An individual’s collection of genes. Genotypes are expressed when its genetic code is used to make protein and RNAmolecules. This​ expression contributes to the individual’s observable traits, called the ​pheno​type​.​

(glahy-koh-LIP-id) A lipid bound to a sugar.​

(glahy-koh-PROH-teen) A protein bound to a sugar.

(glahy-koh-SAHY-uhns) A branch of chemistry dedicated to the study of the many types of carbohydrate molecules.​

(glahy-kah-sih-LAY-shun) The process of adding specialized chains of sugar molecules to proteins or lipids; occurs in the endoplasmic reticulum and Golgi.​

(GAWL-jee) Also called the Golgi apparatus or Golgi complex; an organelle composed of membranous sacs in which many newly made proteins mature and become functional.


(HAP-loid) A cell with one copy of each chromosome, as in a sperm or egg.​

(HIS-tohn) A type of protein found in chromosomes; DNA wraps around histones.

A chemical messenger that affects processes in the body such as growth and development, turning food into energy, sexual function and reproduction, and mood. Hormones are made in one part of the body and travel through the bloodstream to tissues and organs. Examples include insulin, estrogen, and testosterone.​

An organic molecule consisting of hydrogen and carbon atoms only.​


When immune cells, also known as white blood cells, find antigens and prompt the body to make antibodies to fight the infection.​

​​​A network of cells, tissues, and organs that work together to protect the body from infection.​

For more, check out our Biomedical Beat blog post: What Is the Immune System?

The branch of biology and medicine dealing with the immune system.​

For more, check out our Biomedical Beat blog post: What Is the Immune System?

(im-yoo-noh-MAH-juh-LAY-tur) A substance that stimulates or suppresses the immune system and may help the body fight cancer, infection, or other diseases.​

(im-yoo-noh-THAYR-uh-pee) A medical treatment to stimulate or suppress a patient's immune system to help the body fight disease. Health care providers can use immunotherapy to treat patients with cancer or after an organ transplant, among other uses.​

When a gene may be expressed differently in an offspring depending on the sex of the parent who passed on the gene.

The body's response to infection or injury, causing redness, swelling, heat, and pain.​

A molecule that "inhibits," or blocks, the biological action of another molecule.

Referring to a substance not derived from a living organism and/or not composed of carbon and hydrogen. Opposite of organic.

​An injury to the body or a body part, or something that causes or could potentially ​cause such injury.​​

For more, check out our Biomedical Beat blog post: In Other Words: Insult—A "Sick Burn" or a Burn That Makes You Sick?

​The group of animals that don’t have a backbone. Examples include flies, worms, jellyfish, spiders, clams, and snails.​

An electrically charged atom.​

(AHY-suh-tohp) A form of a chemical element that contains the same number of protons but a different number of neutrons than other forms of the element. Researchers often use isotopes to trace atoms or molecules in a metabolic pathway.


Any of a diverse group of organic compounds that don't dissolve in water. Lipids include fats and oils, phospholipids (large components of cellmembranes), waxes, and steroids (including cholesterol, a precursor to many hormones).

For more, check out our Biomedica​l Beat blog post: Science Snippet: Lipids In the Limelight

A substance containing both proteins and lipids. Insoluble ones are found in cell membranes. Soluble ones are found in blood and transport hydrophobic lipids, such as cholesterol​, through the body.​

(LAHY-puh-sohm) An oily, microscopic capsule designed to package and deliver biological cargo, such as drugs, to cells in the body.

For more, check out our Biomedica​l Beat blog post: Science Snippet: Lipids In the Limelight

(LAHY-suh-sohm) A bubblelike organelle that contains powerful enzymes that break apart biological materials into nutrients and building blocks. Lysosomes also break apart waste and transport the waste to the outside of the cell.​


An approach to artificial intelligence in which a computer algorithm (a set of rules and procedures) is developed to analyze and make predictions from data that is fed into the system. Machine learning-based technologies are routinely used every day, such as personalized news feeds and traffic prediction maps.​​​

(spek-TROM-ih-tree) An analytical technique used to determine the composition and abundance of the atoms in a molecular substance. Typical applications include dating of geologic samples; analysis of inorganic and organic chemicals, especially for small amounts of impurities; and determining the structural formula of complex organic substances.​

An area of study involved with designing and making medicines for use in humans and animals.​

A type of drug—a chemical or biological molecule—that is regulated by the Food and Drug Administration (FDA) to diagnose, treat, or prevent specific health issues.​

For more, check out our Biomedical Beat blog post: What Is Pharmacology?

(mahy-OH-sis) The type of cell division that makes egg and sperm cells. Meiosis generates cells that are genetically different from one another and contain half the total number of chromosomes in the parent cell. The other type of cell division is mitosis.​

For more, check out our Biomedical Beat blog post: ​Make Like a Cell and Split: Comparing Mitosis and Meiosis

A semi-fluid layer of lipids and proteins. Membranes enclose cells and organelles and control passage of materials into and out of them.​

For more, check out our Biomedical Beat blog post: Science Snippet: The Marvels of Membranes

(met-uh-BOL-ik) A linked series of chemical reactions occurring within a cell that build up or break down organic molecules, releasing or using energy in the process, called metabolism.​

The chemical changes that occur in a cell or an organism to break down a molecule, whether food, medicines, or biological substances, by enzymes. Metabolism produces energy and materials needed for growth and also gets rid of toxic substances. The product of a metabolic reaction is called a metabolite.

For more, check out our Biomedical Beat blog post: What Happens to Medicine in Your Body?

(muh-TAB-uh-lahyt) A substance made or used when the body breaks down food, drugs, or chemicals through metabolism​. ​

A technology used to study the expression of many genes at once. A scientist places thousands of gene sequences in known locations on a glass slide called a gene chip. A sample containing DNA or RNA is placed in contact with the gene chip. Light is produced to show genes expressed in the sample.

A general term describing microscopic agents that can cause diseases and infect hosts or can be in beneficial symbiotic relationships with hosts. The term includes viruses and microorganisms like bacteria and fungi.

The branch of biology dealing with the study of microorganisms.

(mahy-kroh-BAHY-ohm) All the microbes—including bacteria, viruses​, and fungi—that live on or in an environment, such as the skin or digestive system. Scientists study the human microbiome to learn more about its role in human health. Some people use the terms microbiome and microbiota interchangeably, but others distinguish the term microbiome as referring to only the genomes of these microbes.

An organism that can be seen only with the aid of a microscope and is usually just a single cell.​

A short piece of RNA that binds to messenger RNA, blocking its ability to make proteins.​

A technique used to visualize objects with a microscope. The microscope creates a magnified image by directing a beam of light at the object and through one or a series of lenses. The image is in color and can be observed with the eye directly or recorded as a photo or video.​

(mahy-tuh-KON-dree-uhn) (plural: mitochondria) The cell's power plant; the organelle that converts food and oxygen into energy to fuel the cell. Mitochondria contain their own small genomes and appear to have descended from free-living bacteria.​

For more, check out our Biomedical Beat blog post: The Maternal Magic of Mitochondria

(mahy-TOH-sis) The type of cell division that eukaryotic cells use to make new body cells. Mitosis results in two daughter cells that are genetically identical to the parent cell. The other type of cell division is meiosis.​​​

For more, check out our Biomedical Beat blog post: ​Make Like a Cell and Split: Comparing Mitosis and Meiosis

A small group of research organisms that help us understand the biology of humans. Examples include yeast, fruit flies, worms, zebrafish, and mice.

​Molecular describes things related to, consisting of, or produced by molecules.​​​

The study of molecular structures, their chemical and physical characteristics, and their behaviors in different environments using theoretical and computational techniques.​

The molecule researchers design a drug to bind to, producing therapeutic effects. Often, these molecules are receptors, and the drug can be an agonist that activates the receptor or an antagonist that blocks the receptor.​

The smallest unit of matter that retains all of the physical and chemical properties of that substance. It consists of one or more identical atoms or a group of different atoms bonded together. For example, a water molecule contains two hydrogen atoms and one oxygen atom.​

A variant, or DNA change, in an organism. In humans, usually refers to a ​disease-causing change.​

(MAHY-uh-lin) A fatty covering that protects nerve fibers and makes nerve signals move quickly through the nervous system.​


A particle that is less than 100 nanometers (one-billionth of a meter) in all dimensions. They can be used as drug delivery systems for the targeted delivery and/or controlled release of drugs, such as antibodies, imaging agents, and cancer treatments, throughout the body. Also called nanomaterials. ​

For more, check out our Biomedical Beat blog post: Science Snippet: Z​ooming In on Nanoparticles.

(NAN-uh-tek-nol-uh-jee) Study of the control of matter on an atomic and molecular scale. A nanometer is one-billionth of a meter, or about the circumference of a marble in comparison to that of the Earth. Researchers can use nanotechnology across many fields of science, such as chemistry, biology, physics, and materials science.

A molecule produced by a living organism—a plant, marine organism, or mic​roorganism—that often has a medicinal us​​e.

(neh-KROH-sis) Cell death caused by trauma or infection. One other type of cell death is called apoptosis.​

For more, check out our Biomedical Beat blog post: Why Do Cells Die?

A type of stem cell. Neoblasts are found throughout the planarian worm anatomy and are responsible for regeneration.​​

A cell in the nervous system that carries information through elec​trical impulses and chemical messengers. Also called a neuron.​

For more, check out our Biomedical Beat blog post: Science Snippet: Get to Know Your Nerve Cells!

(nyoor-oh-TRANS-mit-ur) A chemical messenger that passes signals between nerve cells or between a nerve cell and another type of cell.​

Non-steroidal anti-inflammatory drug, such as aspirin or ibuprofen, that reduces pain and inflammation.​

(NOO-klee-ur) A barrier that encloses the nucleus of a cell and controls the passage of molecules between the nucleus and cytoplasm. For example, RNA molecules made in the nucleus need to be passed into the cytoplasm for protein synthesis.​

(NOO-klee-ur mag-NET-ik REZ-uh-nuhns spek-TROS-kuh-pee) A technique used to determine the detailed, three-dimensional structure of molecules and, more broadly, to study the physical, chemical, and biological properties of matter. It uses a strong magnet that interacts with the natural magnetic properties in atomicnuclei.​​

​(noo-KLAY-ik): Large biomolecules that are essential in cells and viruses to store and express genomic information. Deoxyribonucleic acid (DNA) encodes the information cells need to make proteins. Ribonucleic acid (RNA) comes in different forms that play multiple cellular roles, including protein synthesis.​

(NOO-klee-uh-tahyd) A building block of DNA or RNA. It includes one base, one phosphate molecule, and one sugar molecule (deoxyribose in DNA, ribose in RNA). Thousands of nucleotides bind together to form a molecule of DNA or RNA.

(NOO-klee-uhs) (plural: nuclei) Biology: The membrane-bound structure within a eukaryotic cell that contains most of the cell's genetic material. Chemistry: The positively charged core of an atom, consisting of protons and neutrons.


(OH-uh-sahyt) The developing female reproductive cell; an immature egg.

A group of cells and tissues that perform a specific job, including the heart, brain, kidneys, liver, and lung.

(Ohr-guh-NEL) A specialized structure that has a defined function in the cell. Organelles include the nucleus, mitochondria, Golgi, endoplasmic reticulum (ER), and lysosomes.​

For more, check out our Biomedical Beat blog post: Take a Tour of Your Cells' Organelles!

Referring to carbon-containing compounds that are the basis for all living organisms. Opposite of inorganic.​

For more, check out our Biomedical Beat blog post: In Other Words: What's It Mean to Be Organic?

An individual animal, plant, or single-celled life form.​

The production and development of the organs of an animal or plant.​​

(OHR-guh-noyd): A 3D, mini-organ-like structure made by growing stem cells in the laboratory. They contain many types of cells and closely mimic the structure, organization, and some of the functions of human tissues and organs. They’re used to study how tissues form and respond to certain conditions or drugs.​

Referring to a substance containing a metal atom bonded to an organic atom or atoms (usually carbon).

A system containing human cells or tissues grown inside a microfluidic chip. They mimic the structure and function of different organs and can be used for drug development, disease modeling, and personalized medicine. Also called tissue chips.​


A bacterium, virus, or other microorganism that can cause disease.

A series of actions among molecules in a cell that leads to a certain product or change within that cell, such as spurring cell movement, assembling new molecules, or turning genes on and off.​​​

For more, check out our Biomedical Beat blog post: In Other Words: The Pathways Inside Our Bodies

(PEP-tahyd) A molecule consisting of a chain of amino acids; a small protein fragment.

(puh-RIF-ur-uhl) The part of the nervous system outside of the central nervous system—the bra​in and spine.​​​​

(fahr-muh-koh-dahy-NAM-iks) A branch of pharmacology studying how drugs act on their molecular targets and on the organs and tissues in the body.

For more, check out our Biomedical Beat blog post: How Do Medicines Work?

(fahr-muh-koh-juh-NET-iks) The study of how people's genes affect their bodies’ responses to medicines, often one gene at a time.

For more, check out our Biomedical Beat blog post: What Is Pharmacology?

(fahr-muh-koh-jee-NOHM-iks) The study of how people's genes affect their bodies’ responses to medicines, often encompassing the entire genome.​

For more, check out our Biomedical Beat blog post: What Is Pharmacology?

(fahr-muh-koh-kih-NET-iks) A branch of pharmacology studying the level of a drug and its breakdown products in the blood over time.

For more, check out our Biomedical Beat blog post: What Happens to Medicine in Your Body?

(fahr-muh-KOL-uh-jee) The study of how molecules from outside the body interact with organ systems, for example in cell signaling and communications.​​

For more, check out our Biomedical Beat blog post: What Is Pharmacology?

(FEE-nuh-tahyp): An individual’s observable traits, such as eye color, height, and blood type. Some phenotypic traits are largely determined by environmental factors, but others are largely determined by the individual’s genes. The genetic contribution to the phenotype is called the genotype.

(fos-foh-LIP-id) A type of lipid molecule made up of two fatty acids, a phosphate group (phosphorous and oxygen), and glycerol (a type of alcohol). Fatty acids are long chains containing mostly hydrogen and carbon. The phosphate “head” of a phospholipid attracts water while the fatty acid chains repel water, so the molecules line up in a double layer with phosphate groups on the outside and fatty acids on the inside to form membranes.​

A natural process where green plants, algae, and some bacteria use the sun's energy to make carbohydrates from carbon dioxide and water. The carbohydrates are then broken down to produce energy, allowing the plant to grow.​

A serious injury to the body, such as the following:

  • Blunt-force trauma: When an object or force strikes the body, often causing concussions, deep cuts, or broken bones
  • Penetrating trauma: When an object pierces the skin or body, usually creating an open wound

Surgery can also cause physical trauma, sometimes called a controlled injury.

For more, check out our Biomedical Beat blog post: In Other Words: Insult—A "Sick Burn" or a Burn That Makes You Sick?

(fiz-ee-OL-uh-jee) The study of how living organisms function.

A double layer of phospholipids with embedded proteins that separates the conten​ts of a cell from its outside environment.​​

For more, check out our Biomedical Beat blog post: Science Snippet: The Marvels of Membranes

(POL-uh-mur) A large molecule formed by combining small molecules in a simple repeating pattern.

(PAH-lee-SAK-uh-rahyd) A larg​e ​​carbohydrate​​molecule; also called glycan. Polysaccharides are made up of many small sugar molecules that are joined chemically.​

An emerging approach for disease prevention and treatment that takes into account individual differences in lifestyle, environment, and biology.

(proh-KAYR-ee-oh-tik) A cell that lacks a nucleus, such as a bacterium.

(PRO-tee-uh-zohm) A cellular machine that breaks down proteins that are no longer needed and recycles or removes the resulting molecules.

A large, biological molecule composed of amino acids. Proteins are essential for all life processes. They are arranged in a specific order determined by the genetic code and folded into a specific three-dimensional shape with well-defined structures. Protein structures include alpha helixes, short, spiral-shaped sections, and beta sheets, pleated sections.​

For more, check out our Biomedical Beat blog post: Science Snippet: The Power of Proteins

​The process the body uses to create proteins from amino acids in the cell’s ribosomes.

  • Trans​cription: The first step, in which the information coded in DNA is copied (transcribed) into mRNA
  • Translation: The second step, in which the information encoded in mRNA is us​ed to build the right sequence of amino acids
For more, check out our Biomedical Beat blog post: In Other Words: Translation Isn't Only for Languages

(PROH-tee-ohm) The complete set of proteins made by an organism​. Studying the proteome may lead to a better understanding of which proteins are involved in specific diseases or how medicines could be developed to target proteins and treat disease.

(proh-tee-OM-iks) The systematic, large-scale study of all proteins in an organism.


Descriptive; based on interpretation and observations. Qualitative data helps researchers understand the why and how behind certain behaviors, but it is subjective and unique—unlike quantitative​ data.​

Numbers-based, countable, or measurable. Quantitative data tells researchers how many, how much, or how often through calculations and nu​mbers. It is fixed and universal, unlike ​qualitative data.


Energy that comes from a source at the speed of light in the form of waves with an electric field and a magnetic field. Also called electromagnetic waves.​

Giving off radiation, often through the spontaneous release of energy from an unstabl​e atom to get to a more stable state.​

A substance that reacts with another in a chemical reaction. It can be used to test for the presence of another substance by causing a chemical reaction with it.​​

A protein found on the cell surface to which a signal molecule attaches. This leads to a cascade of reactions involving several other molecules inside the cell. Specific signal molecules bind to specific receptors, fitting together like a key in a lock. Many medicines target receptor proteins, either triggering a response (agonist) or preventing a response (antagonist).​

For more, check out our Biomedical Beat​ blog post: How Do Medicines Work?

(ree-KOM-buh-nuhnt) Hybrid DNA produced in the lab by joining pieces of DNA from different sources.

Regeneration is the natural process of replacing or restoring damaged or missing cells, tissues, organs, and even entire body parts to full function in plants and animals.​

For more, check out our regeneration featured topics page.

(rep-li-KAY-shuhn) The process by which a DNA molecule is copied to make two identical DNA molecules. This process is essential for cell division so that each of the two daughter cells receives the exact same genetic information as the ​original parent cell.​

Any creature that scientists use to study life. Examples range from single-celled organisms such as bacteria to more complex ones such as mice.​

For more, check out our Biomedical Beat blog posts on research organisms.

(RAHY-buh-sohm) A molecular complex in which proteins are made. It’s composed of proteins and ribosomal RNA.​

(RAHY-buh-noo-clay-ik) A long, usually single-stranded chain of nucleotides. There are three major types of RNA, which are all involved in protein synthesis:
  • Messenger RNA (mRNA) is complementary to one of the DNA strands of a gene and carries genetic information to the ribosome for protein synthesis.
  • Transfer RNA (tRNA) works with mRNA to make sure the right amino acids are inserted into the protein being made.
  • Ribosomal RNA (rRNA) (RAHY-buh-sohm-uhl), together with proteins, makes up ribosomes and functions to recognize the mRNA and tRNA that are presented to the ribosomal complex.

Certain viruses contain RNA, instead of DNA, as their genetic material.

For more, check out our Biomedical Beat blog post: Science Snippet: RNA's Remarkable Roles

(POL-uh-muh-rays) An enzyme that makes RNA using DNA as a template in a process called transcription.

When noncoding pieces of RNA, called introns, are removed and coding pieces of RNA, called exons, are joined together to produce an mRNA molecule.

A naturally occurring process in which small pieces of double-stranded RNA are used to prevent translation of messenger RNA. The process occurs in many organisms to silence genes when their protein products are no longer needed. When RNAi doesn’t work as it should, it may lead to certain diseases. RNAi has an important role in basic research allowing scientists to directly observe the effects of the loss of function of specific genes.


A person’s overwhelming or impaired whole-body immune response to an insult—an infection or an injury to the body, or something else that provokes such a response. Most sepsis is caused by bacterial infections, but it can also be caused by viral infections, such as COVID-19 or influenza; fungal infections; or noninfectious insults, such as traumatic injury.​​

For more, check out our sepsis featured topics page.

The effect of a drug, other than the desired effect, sometimes in an organ other than the target organ.

For more, check out our Biomedical Beat​ blog post: How Do Medicines Work?

(tranz-DUHK-shuhn) When chemical, electrical, or biological signals are transmitted into and within a cell.

A cell that can develop into many different cell types in the body. When stem cells divide, they can form more stem cells or other specialized cells.

  • Adult stem cells: Cells found throughout the body that replace tissue damaged by disease, injury, or age
  • Embryonic stem cell (em-bree-ON-ik): A cell found in early embryos that can become any kind of cell in the body
  • Induced pluripotent stem cells (iPSC) (ploor-uh-POHT-nt): Specialized tissue or organ cells that have been reprogrammed in a lab into a stem cell-like state and can become just about any cell type

The study of how biological molecules are built. Imaging techniques allow scientists to view molecules in three dimensions to see how they are put together, how they function, and how they interact.

A molecule that binds to an enzyme and undergoes a chemical change during the ensuing reaction.

A relationship between members of any two unrelated species. Symbiotic relationships are defined by how the members benefit from the relationship.
  • Mutualistic: Both organisms benefit from their interaction.
  • Commensal: One organism benefits from the interaction while the other is not helped nor harmed.
  • Parasitic:​ One organism benefits from the interaction while the other is harmed.

(SING-kruh-tron) A large machine that accelerates electrically charged particles to nearly the speed of light and maintains them in circular orbits. Originally designed for use by high-energy physicists, synchrotrons are now heavily used by structural biologists as a source of very intense X-rays.

Made by chemical synthesis, often to imitate a natural product or to form more complex chemical molecules from simpler building blocks.

A field focused on the study of relationships and interactions between various parts of a biological system (metabolic pathways, organelles, cells, and organisms) and that integrates this information to understand how biological systems function.


(tuh-LOM-uh-rays) An enzyme that adds a repetitive segment of DNA, or telomere, to the ends of chromosomes, so the chromosomes don’t shrink during each cell division.

A group of cells that act together to carry out a specific function in the body. Examples include muscle tissue, nervous system tissue (including the brain, spinal cord, and nerves), and connective tissue (including ligaments, tendons, bones, and fat). Organs are made up of tissues.

For more, check out our Biomedical Beat blog post: In Other Words: Not All Tissues Are For Runny Noses

A field of study that combines cells, engineering, and materials methods, with the goal of improving or replacing biological functions.

(tran-SKRIP-shun): The process of making an RNA copy of a piece of DNA. This copy, called messenger RNA (mRNA), carries th​e genetic information needed to make proteins in a cell. It leaves the cell nucleus and enters the cytoplasm, where it directs protein synthesis.

The process of making proteins based on genetic information encoded in messenger RNA. Translation occurs in ribosomes.​

For more, check out our Biomedical Beat blog post: In Other Words: Translation Isn't Only for Languages

The most powerful type of electron microscopy (EM), which uses electrons to create an image of a sample. TEM can magnify objects more than 10 million times, making the outline and some details of cells, viruses, and even some large molecules visible.


(yoo-BIH-kweh-tin) A small protein that attaches to and marks other proteins for the proteasome to destroy.


A permanent change in a DNA sequence that makes up a gene. Variants in genes can cause disease, affect fetal development, or result in differences in how people’s bodies look or work; but they may not cause disease or have any effect at all. Exposure to some types of radiation, chemicals, or viral infections can produce variants; or they can be generated during cell division or DNA replication. Variants in egg or sperm cells can be passed on to offspring, while those in body cells aren't passed on. The term mutation has often been used to describe a disease-causing variant. Related to genetic variation.​

DNA sequence differences among individuals or populations. Some variants influence biological function, while others have no biological effects.​

​The group of animals that have a spine/backbone inside their body. Examples include mammals, fish, reptiles, an​d birds.​​

(VES-ih-kuhl) A small, membrane-bounded sac that transports substances between organelles as well as to and from the cell membrane.​

An infectious agent composed of proteins and genetic material (either DNA or RNA) that requires being in a host cell, such as a plant, animal, or bacterium, in order to reproduce. A virus is neither a cell nor a living organism because it can't reproduce on its own.​


(kris-tl-OG-ruh-fee) A technique used to determine the detailed, three-dimensional structure of molecules. It’s based on the scattering of X-rays through a crystal of the molecule under study.​

A tool that uses beams of fast-moving electrons to determine the 3D structures of molecules. Unlike conventional electron lasers, it uses unbound, or “free,” electrons accelerated to produce X-ray radiation. It can capture chemical processes while they’re taking place.​


A type of microorganism commonly used to make fermented foods (bread, cheese, alcoholic drinks, etc.) that is also often used as a research organism because of its ease of manipulation during experiments, its similarity to human cells, and its rapid growth rate.


(ZAHY-goht) A cell resulting from fusing an egg and a sperm.