Glossary of cellular and molecular biology (M–Z)

mitochondria; also formerly chondriosome.Also M phase.Also somatic crossing over.Also phosphorodiamidate Morpholino oligomer.Also polylinker.

Also negative regulation.Sometimes used interchangeably with nucleobase or simply base.Also non-standard amino acid.Also point-nonsense mutation.Also nonsynonymous substitution or replacement mutation.Also amine terminus and amino terminus.Also nuclear localization sequence.Sometimes used interchangeably with nitrogenous base or simply base.Also prokaryon.Also karyoplasm.Also karyolymph or nuclear hyaloplasm.Also nucleoside monophosphate (NMP).pl.

nuclei Also abbreviated oligo.Also one gene–one protein or one gene–one enzyme.Also umber.Also replication origin or simply origin.Also osmotic stress.

Also synthesis phase or synthetic phase.Also selfish DNA or parasitic DNA.Denoted in shorthand with the symbol p.Also vegetal cell or soma.Also intergenic spacer (IGS) or non-transcribed spacer (NTS).Also hairpin or hairpin loop.Also termination codon.Also sumoylation.Also symplasm; pl.

Also Goldberg-Hogness box.Also antisense strand, negative (-) sense strand, and noncoding strand.Also deoxythymidine.Also 5-methyluracil.Also transcription initiation site.Formerly referred to as soluble RNA (sRNA).Also transporter.Also transposon.Also triacylglycerol and triacylglyceride.Also tropic movement.Also turgidity.

The structure of a typical mature protein-coding messenger RNA or mRNA , drawn approximately to scale. The coding sequence (green) is bounded by untranslated regions at both the 5'-end (yellow) and the 3'-end (pink). Prior to export from the nucleus, a 5' cap (red) and a 3' poly(A) tail (black) are added to help stabilize the mRNA and prevent its degradation by ribonucleases.
An outline of how molecular cloning works
The nucleobases (blue) are the five specific nitrogenous bases canonically used in DNA and RNA. A nucleobase bonded to a pentose sugar (either ribose or deoxyribose ; yellow) is known as a nucleoside (yellow + blue). A nucleoside bonded to a single phosphate group (red) is known as a nucleoside monophosphate (NMP) or a nucleotide (red + yellow + blue). When not incorporated into a nucleic acid chain, free nucleosides can bind multiple phosphate groups: two phosphates yields a nucleoside diphosphate (NDP), and three yields a nucleoside triphosphate (NTP).
A defining element of nucleic acid structure is the linear chain of alternating sugars (orange) and phosphates (yellow) known as the phosphate backbone , which acts as a scaffold to which nucleobases are attached. The phosphorus atom of each phosphate group forms two ester bonds to specific carbon atoms within the pentose sugars— ribose in RNA and deoxyribose in DNA—of two adjacent nucleosides.
A cell's ploidy level is defined by the number of copies it has of each specific chromosome: if the cell has two copies of each of three distinct chromosomes, it is said to be diploid (2N).
A reciprocal translocation between chromosome 4 and chromosome 20
A double-stranded DNA molecule containing the sequence GAATTC and its palindromic complement CTTAAG , a restriction site for the bacterial enzyme EcoRI , is recognized and cut or "digested" in the manner shown here, with the enzyme breaking phosphodiester bonds in the backbones of both strands and leaving behind "sticky" overhangs at the ends of each of the now separate molecules.
An outline of the Sanger sequencing method
Three different modes of DNA replication . In semiconservative replication , each of the two daughter molecules is built from one of the original parental strands and one newly synthesized strand. In conservative replication , the original parent molecule remains intact while the replicated molecule is composed of two newly synthesized strands. In dispersive replication , each of the daughter molecules is an uneven mix of old and new, with some segments consisting of the two parental strands and others consisting of two newly synthesized strands. Only semiconservative replication occurs naturally.
A sequence logo depicts the statistical frequency with which each nucleobase (or amino acid) occurs within a given sequence . Each position in the sequence is represented by a vertical stack of letters; the total height of the stack indicates the degree of consensus at that position between all of the aligned sequences, and the height of each individual letter in the stack indicates the proportion of the aligned sequences having that nucleobase at that position. A single very large letter filling most of the stack indicates that most or all of the aligned sequences have that particular nucleobase at that position.
The standard genetic code specifies a set of 20 different amino acids from triplet arrangements of the four different RNA nucleobases ( A , G , C , and U ). To read this chart, choose one of the four letters in the innermost ring and then move outward, adding two more letters to complete a codon triplet: a total of 64 unique codons can be made this way, 61 of which signal the addition of one of the 20 amino acids (identified by single-letter abbreviation as well as by full name and chemical structure) to a nascent peptide chain, while the remaining three codons are stop codons signalling the termination of translation. Also indicated are some of the chemical properties of the amino acids and the various ways in which they can be modified.
A simplified diagram of transcription . RNA polymerase (RNAP) synthesizes an RNA transcript (blue) in the 5'-to-3' direction, using one of the DNA strands as a template , while a complex of multiple transcription factors binds to a promoter upstream of the gene.