Molecular Biology Terms
Molecular biology explains life at the level of DNA, RNA and proteins. These terms cover how genetic information is copied, transcribed and translated, how genes are switched on and off, and the lab techniques used to study and edit them.
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B
- BacteriophageVirologyA bacteriophage, or phage, is a virus that infects bacteria, injecting its genome and using the host cell's machinery to make new phages.
- BioBrickSynthetic BiologyA BioBrick is a standardized piece of DNA, such as a promoter or gene, flanked by fixed sequences so it can be joined to other parts in a repeatable way.
- BioinformaticsBioinformaticsBioinformatics is the science of using computers to gather, store, analyze and share biological data, especially DNA, RNA and protein sequences.
- BiotechnologyBiotechnologyBiotechnology is the use of living organisms, cells or their molecules to make products or carry out processes that are useful to people.
- BLASTBioinformaticsBLAST is a widely used program that searches databases for DNA or protein sequences similar to a query and ranks the matches by statistical significance.
C
- CapsidVirologyA capsid is the protein shell of a virus that surrounds and protects its genome, built from many repeating protein subunits called capsomeres.
- Central dogmaMolecular BiologyThe central dogma is the principle that genetic information flows from DNA into RNA and then into protein, and never back from protein into nucleic acid.
- ChromatinCell BiologyChromatin is the complex of DNA and proteins, mainly histones, that packs a eukaryotic cell's genome into its nucleus and makes up its chromosomes.
- ChromosomeGeneticsA chromosome is a thread-like structure of DNA and protein that carries an organism's genes; most human cells hold 46 of them in 23 pairs.
- CodonMolecular BiologyA codon is a sequence of three nucleotides in DNA or messenger RNA that stands for one amino acid or tells the ribosome to stop.
- Complementary DNAMolecular BiologyComplementary DNA is DNA built from an RNA template, usually messenger RNA, by the enzyme reverse transcriptase, giving a DNA copy of an expressed gene.
- CRISPRBiotechnologyCRISPR is a genome-editing technology, adapted from a bacterial defense system, that uses a guide RNA to direct an enzyme such as Cas9 to cut DNA.
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.
- 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 ligaseMolecular BiologyDNA ligase is an enzyme that links two pieces of DNA end to end, making a phosphodiester bond that seals a break in the sugar-phosphate backbone.
- DNA methylationMolecular BiologyDNA methylation is the addition of a small methyl group to DNA, usually on cytosine, which can switch a gene off without changing its sequence.
- 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.
- DNA repairMolecular BiologyDNA repair is the set of processes by which cells detect and correct damage and copying errors in their DNA, protecting the genome from mutation.
- DNA replicationMolecular BiologyDNA replication is how a cell copies all of its DNA before it divides, so that each daughter cell receives a complete genome.
E
- EnzymeBiochemistryAn enzyme is a biological catalyst, usually a protein, that speeds up a specific chemical reaction without being used up in the process.
- EpigeneticsMolecular BiologyEpigenetics is the study of chemical marks on DNA and its packaging proteins that switch genes on or off without changing the DNA sequence.
- Escherichia coliMicrobiologyEscherichia coli is a rod-shaped, gram-negative gut bacterium that is mostly harmless but includes strains that cause diarrhea and urinary infections.
- ExonMolecular BiologyAn exon is a section of a gene that stays in the final RNA after splicing removes the introns, and most exons carry code for protein.
F
- FASTA formatBioinformaticsFASTA format is a plain-text format for DNA, RNA or protein sequences in which each record starts with a header line beginning with > followed by the sequence.
- Frameshift mutationGeneticsA frameshift mutation is an insertion or deletion of DNA bases, in a number not divisible by three, that shifts how the rest of a gene's codons are read.
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.
- GeneGeneticsA gene is a stretch of DNA that carries the instructions for making a protein or a working RNA molecule, and is the basic unit of heredity.
- Gene expressionMolecular BiologyGene expression is the use of a gene's information to make a working product, usually a protein or a functional RNA molecule.
- Genetic circuitSynthetic BiologyA genetic circuit is a designed set of genes and regulatory DNA that lets a cell sense inputs and respond in a programmed way, like an electronic circuit.
- Genetic engineeringBiotechnologyGenetic engineering is the direct change of an organism's DNA using laboratory techniques, to add, remove or alter genes and give it new traits.
H
- HelicaseMolecular BiologyA helicase is an enzyme that uses energy from ATP to unwind a nucleic acid double helix, separating the two strands so they can be copied or repaired.
- HistoneMolecular BiologyA histone is a small, positively charged protein that DNA winds around to form nucleosomes, packing DNA in the nucleus and helping control gene activity.
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M
- Messenger RNAMolecular BiologyMessenger RNA is the RNA copy of a gene that carries protein-building instructions from DNA to the ribosomes, where it is read in three-base codons.
- MicroRNAMolecular BiologyA microRNA is a short RNA, about 22 nucleotides long, that does not code for protein but silences genes by pairing with their messenger RNAs.
- Molecular cloningBiotechnologyMolecular cloning is a set of laboratory methods for inserting a specific DNA fragment into a vector and copying it many times inside host cells.
- MorphogenDevelopmental BiologyA morphogen is a signaling molecule that spreads through developing tissue as a gradient, so cells adopt different fates depending on how much they receive.
- MutationGeneticsA mutation is a lasting change in an organism's DNA sequence, ranging from a single altered base to large rearrangements of chromosomes.
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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.
- OncogeneOncologyAn oncogene is a mutated or overactive form of a normal growth-promoting gene that pushes cells to divide uncontrollably and can cause cancer.
- OperonMolecular BiologyAn operon is a cluster of genes in bacteria that share one promoter, are switched on and off together and are copied into a single messenger RNA.
P
- PlasmidMolecular BiologyA plasmid is a small, usually circular DNA molecule that copies itself independently of the main chromosome, found mostly in bacteria.
- Polymerase chain reactionMolecular BiologyThe polymerase chain reaction (PCR) is a lab technique that copies one chosen stretch of DNA over and over until there are billions of copies.
- 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.
- PromoterMolecular BiologyIn molecular biology, a promoter is a stretch of DNA, usually just upstream of a gene, where RNA polymerase binds so that transcription can begin.
- 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.
- ProteomeProteomicsA proteome is the complete collection of proteins made by a cell, tissue or organism at a given time, including all their modified forms.
- 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
- Quantitative PCRMolecular BiologyQuantitative PCR (qPCR) is a form of PCR that tracks DNA copying by fluorescence after every cycle to measure how much of a target sequence is present.
- Quaternary structureBiochemistryQuaternary structure is the way two or more folded polypeptide chains, called subunits, fit together to form a single working protein.
- Quorum sensingMicrobiologyQuorum sensing is a system of chemical signals that lets bacteria sense how crowded their population is and switch genes on or off together.
R
- Recombinant DNABiotechnologyRecombinant DNA is DNA made in the laboratory by joining pieces of DNA from different sources, often different species, into one molecule.
- Reporter geneMolecular BiologyA reporter gene is a gene whose product is easy to see or measure, joined to DNA of interest so that its activity or location can be tracked.
- Restriction enzymeMolecular BiologyA restriction enzyme is a bacterial protein that cuts DNA at a specific short sequence, making it a basic tool for cutting and joining DNA.
- RetrovirusVirologyA retrovirus is an RNA virus that copies its genome into DNA with reverse transcriptase and inserts that DNA into the host cell's chromosomes.
- Reverse transcriptaseVirologyReverse transcriptase is an enzyme that builds DNA from an RNA template, letting retroviruses such as HIV turn their RNA genome into DNA.
- RibosomeCell BiologyA ribosome is a molecular machine of RNA and protein that reads messenger RNA and joins amino acids in the order it specifies to build a protein.
- Ribosome binding siteMolecular BiologyA ribosome binding site is a short stretch of messenger RNA just before the start codon where a ribosome attaches to begin translating a bacterial gene.
- RNAMolecular BiologyRNA is a usually single-stranded nucleic acid, built with the sugar ribose and the base uracil, that carries and uses genetic information to make proteins.
- RNA interferenceMolecular BiologyRNA interference is a natural process in which small RNA molecules guide the destruction or blocking of matching messenger RNAs, silencing specific genes.
- RNA sequencingGenomicsRNA sequencing (RNA-seq) is a method that uses high-throughput sequencing to identify and count the RNA molecules in a sample.
- RNA splicingMolecular BiologyRNA splicing is the step in which introns are cut out of a newly made RNA and its exons are joined, producing a mature RNA ready for use.
S
- Sanger sequencingGenomicsSanger sequencing is a method for reading the order of bases in DNA that uses chain-terminating nucleotides, developed by Frederick Sanger in the 1970s.
- Sequence alignmentBioinformaticsSequence alignment is a way of lining up two or more DNA, RNA or protein sequences so that matching positions share a column, showing how similar they are.
- Southern blotMolecular BiologyA Southern blot is a laboratory method that finds a specific DNA sequence by separating DNA fragments on a gel, moving them to a membrane and probing them.
- Synthetic biologySynthetic BiologySynthetic biology applies engineering design to living systems, building new genetic parts, circuits and genomes so that organisms can do useful jobs.
- Systems biologyBioinformaticsSystems biology studies how genes, proteins, metabolites and cells work together as networks, using big datasets and computer models to explain the whole.
T
- TranscriptionMolecular BiologyTranscription is the process in which a cell copies the DNA sequence of a gene into a matching strand of RNA.
- Transcription factorMolecular BiologyA transcription factor is a protein that binds specific DNA sequences and controls whether, when and how strongly a nearby gene is transcribed into RNA.
- TranscriptomeGenomicsThe transcriptome is the full set of RNA molecules made in a cell, tissue or organism at a given time, showing which genes are active.
- 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.
- TransposonGeneticsA transposon is a DNA sequence that can move from one place in a genome to another, in some cases leaving a copy behind as it goes.
- Tumor suppressor geneOncologyA tumor suppressor gene makes a protein that restrains cell division or repairs damage, so losing both working copies can help a cell turn cancerous.
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.
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