Biochemistry Terms
Biochemistry is the chemistry of life: the molecules cells are built from and the reactions that run them. These terms cover enzymes and how fast they work, how cells release energy from food, and the structure of proteins, lipids, carbohydrates and nucleic acids.
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A
- Active siteBiochemistryThe active site is the pocket or groove on an enzyme where the substrate binds and the chemical reaction is catalyzed.
- Allosteric regulationBiochemistryAllosteric regulation is control of an enzyme's activity by a molecule that binds somewhere other than the active site and changes the enzyme's shape.
- Amino acidBiochemistryAn amino acid is a small organic molecule with an amino group, a carboxyl group and a side chain; amino acids link together to form proteins.
- AntioxidantFood NutritionAn antioxidant is a substance that prevents or slows oxidation, especially damage to cells from free radicals and other reactive oxygen species.
- ATPBiochemistryATP (adenosine triphosphate) is the molecule cells use as their main short-term energy carrier, releasing energy when a phosphate group is removed.
B
- Beta oxidationBiochemistryBeta oxidation is the pathway, mainly in mitochondria, that breaks fatty acids down two carbons at a time into acetyl CoA, yielding NADH and FADH2.
- BioluminescenceMarine BiologyBioluminescence is the production of light by a living organism through a chemical reaction, as seen in fireflies and in many deep-sea animals.
C
- CalorieFood NutritionA calorie is a unit of energy, the heat needed to warm one gram of water by one degree Celsius; food energy is given in kilocalories, often written Calories.
- CarbohydrateBiochemistryA carbohydrate is a sugar or a chain of sugars, such as starch or cellulose, built from carbon, hydrogen and oxygen and used for energy and structure.
- Cell membraneCell BiologyThe cell membrane is the thin, flexible boundary of lipids and proteins that encloses every cell and controls what enters and leaves it.
- Cellular respirationCell BiologyCellular respiration is the set of pathways by which cells break down fuel molecules such as glucose and capture the released energy as ATP.
- CelluloseBotanyCellulose is a strong, unbranched polysaccharide of glucose units joined by beta 1-4 bonds and the main structural material of plant cell walls.
- ChitinEntomologyChitin is a tough, nitrogen-containing polysaccharide built from N-acetylglucosamine units that forms arthropod exoskeletons and fungal cell walls.
- ChlorophyllBotanyChlorophyll is the green pigment in plants, algae and cyanobacteria that absorbs light energy to drive photosynthesis.
- CholesterolBiochemistryCholesterol is a waxy steroid lipid found in animal cell membranes and used to make steroid hormones, vitamin D and the bile salts that digest fat.
- Citric acid cycleBiochemistryThe citric acid cycle is a loop of reactions in mitochondria that breaks down acetyl groups to carbon dioxide, capturing energy as NADH and FADH2.
- CoenzymeBiochemistryA coenzyme is a small organic molecule, often made from a vitamin, that an enzyme needs to catalyze its reaction, usually by carrying electrons or atoms.
- Competitive inhibitionBiochemistryCompetitive inhibition is enzyme inhibition in which a molecule resembling the substrate occupies the active site and keeps the substrate out.
- Complement systemImmunologyThe complement system is a set of blood proteins that switch each other on in a cascade to tag microbes, drive inflammation and punch holes in them.
- CortisolPhysiologyCortisol is a steroid hormone made by the adrenal cortex that helps the body cope with stress, raises blood glucose and dampens inflammation.
- Cytochrome P450PharmacologyCytochrome P450 is a large family of heme-containing enzymes that oxidize drugs, toxins and the body's own molecules, working mainly in the liver.
D
- DenaturationBiochemistryIn biochemistry, denaturation is the unfolding of a protein or nucleic acid by heat, acid or chemicals, which ruins its shape but not its sequence.
- DigestionPhysiologyDigestion is the process by which the body breaks food down, by chewing, churning and enzymes, into molecules small enough to absorb into the blood.
- DNAMolecular BiologyDNA is the double-stranded molecule that carries the genetic instructions of nearly all living things, written in a code of four bases: A, T, C and G.
- DNA polymeraseMolecular BiologyDNA polymerase is an enzyme that builds new DNA by adding nucleotides one at a time to a growing strand, using an existing strand as a template.
E
- Electron transport chainBiochemistryThe electron transport chain is a series of membrane proteins that pass electrons to oxygen and use the energy released to pump protons.
- ELISAImmunologyELISA is a lab test that uses enzyme-linked antibodies to detect and measure a specific antigen or antibody in a sample through a color change.
- EnzymeBiochemistryAn enzyme is a biological catalyst, usually a protein, that speeds up a specific chemical reaction without being used up in the process.
F
- Fatty acidBiochemistryA fatty acid is a long chain of carbon and hydrogen atoms with a carboxyl group at one end, and is the building block of fats, oils and phospholipids.
- FermentationBiochemistryFermentation is a way cells get energy from sugar without oxygen, passing electrons to an organic molecule so that glycolysis can keep going.
G
- Gel electrophoresisMolecular BiologyGel electrophoresis is a lab technique that uses an electric field to pull DNA, RNA or proteins through a gel, separating them by size.
- GlucagonPhysiologyGlucagon is a peptide hormone made by alpha cells of the pancreas that raises blood glucose, mainly by making the liver release glucose.
- GluconeogenesisBiochemistryGluconeogenesis is the metabolic pathway that makes new glucose from non-carbohydrate sources such as lactate, glycerol and certain amino acids.
- GlucoseBiochemistryGlucose is a six-carbon simple sugar, C6H12O6, that serves as the main fuel for most cells and is the sugar carried in human blood.
- GlycogenBiochemistryGlycogen is a large, highly branched polymer of glucose that animals and fungi use to store carbohydrate, mainly in the liver and skeletal muscle.
- GlycolysisBiochemistryGlycolysis is the ten-step metabolic pathway that splits one glucose molecule into two pyruvate molecules, giving a net gain of two ATP.
H
- HemoglobinPhysiologyHemoglobin is the iron-containing protein in red blood cells that picks up oxygen in the lungs and releases it to the body's tissues.
- HormonePhysiologyA hormone is a chemical messenger released into the blood by a gland or cell that changes the activity of distant target cells with matching receptors.
- Hydrogen bondBiochemistryA hydrogen bond is a weak attraction between a slightly positive hydrogen atom, bonded to oxygen or nitrogen, and a nearby electronegative atom.
I
- InsulinPhysiologyInsulin is a peptide hormone made by beta cells in the pancreas that lowers blood glucose by helping body cells take up and store sugar.
- Isoelectric focusingProteomicsIsoelectric focusing is a technique that separates proteins by their isoelectric point, the pH at which a protein carries no net electric charge.
K
L
- Lineweaver–Burk plotBiochemistryA Lineweaver–Burk plot is a straight-line graph of an enzyme's 1/rate against 1/substrate concentration, used to find Km and Vmax.
- LipidBiochemistryA lipid is one of a varied group of biological molecules, including fats, oils, phospholipids, waxes and steroids, that do not dissolve in water.
- LiverHuman AnatomyThe liver is the largest gland and internal organ, lying in the upper right abdomen, where it makes bile, processes nutrients and clears toxins.
M
- MacronutrientFood NutritionA macronutrient is a nutrient needed in large amounts, namely carbohydrate, protein or fat, which together supply energy and the raw materials for growth.
- Mass spectrometryProteomicsMass spectrometry is an analytical technique that turns molecules into charged ions and sorts them by mass-to-charge ratio to identify and measure them.
- MetabolismBiochemistryMetabolism is the full set of chemical reactions in a cell or organism, both those that break molecules down for energy and those that build them up.
- Michaelis constantBiochemistryThe Michaelis constant (Km) is the substrate concentration at which an enzyme-catalyzed reaction runs at half its maximum rate.
- MitochondrionCell BiologyA mitochondrion is a double-membraned organelle that makes most of a eukaryotic cell's ATP by breaking down fuel molecules with oxygen.
N
- NeurotransmitterNeuroscienceA neurotransmitter is a chemical messenger that a neuron releases at a synapse to excite or inhibit a target neuron, muscle cell or gland cell.
- NucleotideBiochemistryA nucleotide is a single unit of DNA or RNA, made of a nitrogen-containing base, a five-carbon sugar and one or more phosphate groups.
O
- Okazaki fragmentMolecular BiologyAn Okazaki fragment is one of the short pieces of DNA made on the lagging strand during DNA replication and later joined into one continuous strand.
- Omega-3 fatty acidFood NutritionAn omega-3 fatty acid is a polyunsaturated fatty acid whose first double bond is three carbons from the methyl end of its chain, as in ALA, EPA and DHA.
- Oxidative phosphorylationBiochemistryOxidative phosphorylation is how cells make most of their ATP, using a proton gradient built by the electron transport chain to drive ATP synthase.
P
- Peptide bondBiochemistryA peptide bond is the covalent link that joins the carboxyl group of one amino acid to the amino group of the next, releasing a water molecule.
- PeptidoglycanMicrobiologyPeptidoglycan is the mesh-like polymer of sugars and short peptides that forms the bacterial cell wall and gives bacteria their shape and strength.
- pHBiochemistrypH is a number, usually on a scale of 0 to 14, that shows how acidic or basic a water-based solution is from its concentration of hydrogen ions.
- PhospholipidBiochemistryA phospholipid is a lipid with two fatty acid tails and a head containing phosphate, and it is the main building block of all cell membranes.
- PhosphorylationBiochemistryPhosphorylation is the attachment of a phosphate group to a protein, sugar or other molecule, a key way cells make ATP and switch proteins on or off.
- PhotosynthesisBotanyPhotosynthesis is the process in which plants, algae and cyanobacteria capture light energy and store it in sugar built from carbon dioxide and water.
- Post-translational modificationMolecular BiologyA post-translational modification is a chemical change made to a protein after it is built on the ribosome, often altering its activity or location.
- ProteinBiochemistryA protein is a large molecule made of one or more chains of amino acids, folded into a specific shape that determines its job in the body.
- Protein foldingBiochemistryProtein folding is the process by which a newly made chain of amino acids coils and folds into the specific three-dimensional shape it needs to work.
- ProteomicsProteomicsProteomics is the large-scale study of the proteome, the full set of proteins in a cell, tissue or organism, including their amounts, changes and interactions.
Q
R
S
- SDS-PAGEProteomicsSDS-PAGE is a lab technique that separates proteins by size, coating them in a charged detergent and pulling them through a gel with an electric field.
- Signal transductionCell BiologySignal transduction is the chain of molecular events by which a cell turns a signal received at a receptor into a specific response inside the cell.
T
- TranscriptionMolecular BiologyTranscription is the process in which a cell copies the DNA sequence of a gene into a matching strand of RNA.
- Transfer RNAMolecular BiologyTransfer RNA is a short adaptor RNA that brings a specific amino acid to the ribosome and pairs with the matching mRNA codon through its anticodon.
- TranslationMolecular BiologyTranslation is the process in which a ribosome reads the codons of a messenger RNA and links amino acids in that order to build a protein.
- TriglycerideBiochemistryA triglyceride is a fat molecule made of one glycerol joined to three fatty acids, and it is the main form in which the body stores energy.
U
- UbiquitinCell BiologyUbiquitin is a small, highly conserved protein that cells attach to other proteins as a tag, most often to mark them for destruction.
- UracilMolecular BiologyUracil is one of the four nitrogen-containing bases in RNA, where it pairs with adenine and stands in for the thymine found in DNA.
- Urea cycleBiochemistryThe urea cycle is a loop of reactions, mainly in liver cells, that turns toxic ammonia from protein breakdown into urea for excretion in urine.
V
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