amino acidA small molecule with an amino end and an acid end. Twenty standard amino acids are spelled out by the genetic code. Nine of them must come from the human diet, because the body cannot make them.
anticodonThe triplet on a tRNA that matches a codon. Written letter for letter, the anticodon UAC pairs with the codon AUG.
codonA trio of bases that is read as a single unit. Four bases taken three at a time make 64 codons: 61 stand for amino acids and 3 are stop signals.
genetic codeThe rules that turn each codon into an amino acid. The code is very nearly the same in all organisms. With 61 codons for 20 amino acids, most amino acids have more than one codon.
messenger RNAThe working copy of a gene, sent out to be read. It is usually written mRNA. It is read three bases at a time, from the start codon to a stop codon.
nucleotideA single unit of RNA or DNA, carrying one base. The nucleotides of RNA carry the sugar ribose and the bases A, U, C and G. Strung together they make a strand of RNA.
Show all 36 terms (30 more)
From gene to protein, continued
proteinA folded working molecule that a gene codes for. It may be a single chain of amino acids or several chains together. The order of the amino acids decides how the chain folds, and the folded shape decides what the protein does.
ribosomeThe two-part particle on which proteins are made. It is made of RNA and protein, in a large and a small subunit. Ribosomes that make proteins for export attach to the endoplasmic reticulum.
RNA polymeraseThe enzyme that carries out transcription. It binds to a stretch of DNA called a promoter, opens the double helix and adds RNA nucleotides one by one.
transcriptionBuilding RNA on a pattern of DNA. The RNA is made from a DNA template. In eukaryotes it happens inside the nucleus.
transfer RNAA small RNA that brings the ribosome its amino acids. A tRNA is typically 76 to 90 nucleotides long. Each kind carries one particular amino acid.
translationTurning a run of codons into a run of amino acids. It takes place in the cytoplasm, on ribosomes. Its three steps are initiation, elongation and termination.
In the cell 12
base pairingThe matching of A with U and of G with C. In DNA, A pairs with T in place of U. The bases of a pair are held to each other by hydrogen bonds.
eukaryoteAn organism built of cells that each hold a nucleus. Animals, plants and fungi are eukaryotes. Their messenger RNA is made in the nucleus and translated outside it, in the cytoplasm.
exocytosisThe release of a vesicle's contents outside the cell. The vesicle docks at the cell membrane and fuses with it. It is how a cell sends out proteins.
nuclear envelopeThe double membrane wrapped around the nucleus. It keeps the DNA apart from the cytoplasm. Messenger RNA leaves through its pores.
nucleolusThe ribosome factory, a dense spot in the nucleus. It is also where the genes for ribosomal RNA are transcribed. Once assembled, the ribosomes are sent out to the cytoplasm.
prokaryoteA simple cell whose DNA lies loose, not in a nucleus. The bacteria and the archaea are the two groups of prokaryotes. Prokaryotes have ribosomes too, smaller than those in the cytoplasm of a eukaryote.
proteasomeA protein complex that breaks down unneeded proteins. A protein to be destroyed is first tagged with a small protein called ubiquitin. The pieces can be broken down further and used to make new proteins.
RNA processingThe trimming and finishing of new RNA before use. Eukaryotic messenger RNA gets a cap on one end and a tail of adenine nucleotides on the other, and its introns are spliced out.
rough endoplasmic reticulumFolded membranes studded with ribosomes. The ribosomes give it a bumpy look under the microscope. Proteins made here move on to the Golgi apparatus.
start codonAUG, the triplet that opens a message. AUG also stands for the amino acid methionine, so in eukaryotes a new chain begins with methionine.
stop codonUAA, UAG or UGA: the signal that a chain is finished. It stands for no amino acid. Proteins called release factors bind to it, and the finished chain is let go.
vesicleA tiny membrane sac that ferries proteins and more. Proteins that leave the endoplasmic reticulum go on to the Golgi apparatus, and secretory vesicles carry them from there to the cell membrane.
Mutations and gene control 12
dehydration synthesisJoining two molecules by removing a water molecule. Every peptide bond is made this way, between the acid group of one amino acid and the amino group of the next.
deletionA mutation that removes one or more bases. Losing three bases in a row keeps the reading frame. Losing one or two shifts it, so every codon after that point is read differently.
gene regulationThe turning of genes on and off in a cell. It is how a brain cell comes to look and act differently from a cell of the liver or of a muscle.
insertionA mutation that adds one or more bases to DNA. The added piece may be one nucleotide or a whole stretch of a chromosome.
operonA cluster of genes run by a single promoter. Its genes are switched on or off together and are transcribed onto one strand of messenger RNA. Operons are found mostly in prokaryotes.
proteomeThe full set of proteins a cell or organism makes. It differs from one type of cell to another and from one time to another. The word was first used in 1994.
repressorA protein that binds DNA and turns a gene off. It attaches to the gene's promoter region, which stops messenger RNA from being made.
reverse transcriptionThe copying of RNA back into DNA. The enzyme that does it, reverse transcriptase, was discovered in virus particles. Retroviruses use it to copy their RNA into DNA.
ribozymeAn RNA molecule that works as an enzyme. Inside the ribosome it is a ribozyme, part of the ribosomal RNA of the large subunit, that links the amino acids together.
substitutionA mutation that swaps one base for another. The word is also used for the swap of one amino acid for another in a protein.
TATA boxA promoter sequence rich in T and A bases. It lies in the core promoter of some genes of eukaryotes and archaea, though most promoters do not have one. Transcription factors bind to it.
traitAny feature that can be observed, such as height. Eye color is a trait of kind and height a trait of amount. A trait can be set by genes, by the environment or by both together.
How this list was compiled: Term list chosen for this site on 2026-10-12. Each meaning is written in our own words and was checked that day against the article on the term in the English Wikipedia (https://en.wikipedia.org/), whose text is under the Creative Commons Attribution-ShareAlike license: Protein biosynthesis, Transcription (biology), Translation (biology), Genetic code, Transfer RNA, Messenger RNA, Ribosome, RNA polymerase, Protein, Proteinogenic amino acid, Essential amino acid, Nucleotide, Start codon, Stop codon, Base pair, Post-transcriptional modification, Nuclear envelope, Nucleolus, Endoplasmic reticulum, Vesicle (biology and chemistry), Golgi apparatus, Eukaryote, Prokaryote, Exocytosis, Proteasome, Point mutation, Insertion (genetics), Deletion (genetics), Frameshift mutation, Phenotypic trait, Regulation of gene expression, Operon, Repressor, TATA box, Reverse transcriptase, Ribozyme, Dehydration reaction, Peptide bond, Proteome and Central dogma of molecular biology. Transcription, translation, codon, anticodon, ribosome, amino acids, messenger RNA, transfer RNA, protein, genetic code, stop codon, nucleotide, nucleolus, nuclear membrane, rough endoplasmic reticulum, Golgi body, substitution, insertion, deletion, trait, gene regulation, repressor and central dogma were checked a second time against the Talking Glossary of Genomic and Genetic Terms of the National Human Genome Research Institute (https://www.genome.gov/genetics-glossary), and gene regulation also against MedlinePlus Genetics of the National Library of Medicine (https://medlineplus.gov/genetics/understanding/howgeneswork/geneonoff/, Can genes be turned on and off in cells?). The fact after each meaning is from the same pages. Licence: own work
How it works
This protein synthesis vocabulary worksheet lists transcription, translation, codon, anticodon, ribosome, amino acid, messenger RNA, transfer RNA and four more terms beside their meanings in another order. The answer key is the last page, and two more sets follow.
Read the full guide
In the cell
Set opens on From gene to protein. The second set has start codon, stop codon, base pairing, RNA processing, nuclear envelope, nucleolus, rough endoplasmic reticulum, vesicle, eukaryote, prokaryote, exocytosis and proteasome.
Mutations and gene control
The third set has substitution, insertion, deletion, trait, gene regulation, operon, repressor, TATA box, reverse transcription, ribozyme, dehydration synthesis and proteome.
Double helix, replication and the four bases of DNA by name are on the DNA vocabulary worksheets.
Questions and answers
What is the central dogma of molecular biology?
It is the rule for the direction in which genetic information flows: from DNA to RNA to protein. It is often put in one line: DNA makes RNA, and RNA makes protein.
What happens to a protein after translation?
The new chain folds into its shape and is often chemically modified. A protein bound for export is made on the rough endoplasmic reticulum, passes through the Golgi apparatus and leaves the cell in a vesicle.
How does a mutation change a protein?
A substitution changes one codon. The new codon may stand for the same amino acid, for a different one, or for stop, which ends the chain early. An insertion or a deletion can change every codon that follows it.