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Home >> Dictionary of Bioinformatics, Biochemistry, Biotechnology >> Emission Flame Photometry, Endoplasmic Reticulum (ER)
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Embryonic stem cells Cultured cells derived from the pluripotent inner cell mass of blastocyst-stage embryos. Use of stem cells has a number of promising research applications
Emission flame photometry A type of flame photometry in which molecules in a flame are volatilised to generate free atoms that are excited to higher energy levels. When these atoms return to the ground state, they produce a characteristic emission spectrum.
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EMT See embryo multiplication and transfer.
Emulsifier A detergent that is capable of breaking up a mass of insoluble material into small particles that can form an emulsion.
Emulsion A solution of two immiscible liquids, a colloid of one of the liquids is suspended in the other such as oil and water.
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Encapsulating agents An agent that forms a shell around an enzyme or bacterium. Generally, polysaccharides such as alginate or agar are used as encapsulating agents. These are inert and permit nutrients and oxygen to diffuse into and out of the sphere readily, and can be easily converted from gel (solid) to sol (liquid) or solution form by altering the temperature or the concentration of ions.
Encapsulation A method of enveloping a functional enzyme or bacterium within a capsule. It is a method used for the immobilization of cells in a bioreactor.
Encephalitis Inflammation of the brain.
Encephalopathy Degenerative brain disease
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3’-end The terminal nucleotide at one end of a polynucleotide chain, which contains a free 3’-hydroxyl (-OH) group. The other end is the 5’-end.
5’-end The terminal nucleotide at one end of a polypeptide chain that contains a 5’-phosphate group. The other end is the 3’-end.
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End product The final product in a series of enzymatic reactions of a biochemical pathway.
End-product inhibition The inhibition of enzyme activity by a metabolite. Usually the enzyme is the first enzyme in a biosynthetic pathway and the metabolite is the final product in the pathway. Also called feedback inhibition.
Enamel The hard, white, outermost layer of a tooth.
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Enantiomers Isomers that are mirror images of each others.
Encapsidation The process by which the viral nucleic acid in enclosed in a protein capsid. See capsid; coat protein.
End filling Conversion of a sticky ended DNA to a blunt end by enzymatic synthesis of the complementary strand.
End-labelling Incorporating a radioactive molecule at the end(s) of a polynucleotide, DNA or RNA molecule. This is usually done by using T4 polynucleotide kinase to introduce a 32P atom onto the end of a DNA molecule.
End-replication problem The inability of DNA polymerases to replicate ends of linear eukaryotic chromosomes. During replication in eukaryotes, the lagging strand is synthesised discontinuously as short Okazaki fragments. However, when the replication fork reaches the end of a linear chromosome, synthesis of the RNA primer for the last Okazaki fragment becomes a problem, because there is no template available for the RNA primer to bind. This results in an overhang at the telomere ends of the chromosomes with gradual shortening after each round of replication. About 75 TTAGGG repeat sequences are lost during each mitosis.
Emphysema Abnormal accumulation of air in tissues or organs.
Empirical Relating to or based on practical experience, trial and error, direct observation of observation alone, without benefit of scientific method, knowledge or theory.
Endangered species A plant or animal species that is in immediate danger of extinction because its numbers have declined and reached a critical level or its habitats have been drastically reduced.
Endemic 1. Describing a plant or animal species whose distribution is restricted to selected localities. 2. Describing a disease or a pest that is persistent in an area.
Endergonic reaction A reaction that proceeds with a positive free energy change.
Endocrine glands Tissues specialised for the synthesis and secretion of hormones which are subsequently released into the blood and act at distant sites in the body called targets.
Endocrine hormones Hormones synthesised by endocrine glands and transported to their target cells by circulation.
Endocrinology The branch of science concerned with the study of structure, function and pathology of the endocrine glands.
Endocytic vesicles Membranous particles that transport proteins via endocytosis. Also called clathrin0coated vesicles.
Endocytosis The process by which materials that enter a cell without passing through the cell membrane are enclosed in a saclike vesicle. The vesicle is subsequently pinched off from the cell surface so that it lies within the cell. See Phagocytosis; pinocytosis.
Endoderm The internal layer of cells of the gastrula, which eventually develops into the alimentary canal and digestive glands of the adult.
Endogamy The fusion of reproductive cells from closely related parents, i.e., inbreeding.
Endogenote The part of the bacterial chromosome homologous to a genome fragment (exogenote) that is transferred from the donor to the recipient cell during the formation of a merozygote.
Endogenous Developed or added from within the cell or organism.
Endogenous antigen An antigen synthesised in the ell cytoplasm and presented on class I MHC.
Endogenous virus A virus present in a latent form in a cell that can get activated at a later stage on exposure to physical or chemical agents. Examples include some bacteriophage proviruses and some types of herpes viruses.
Endometrium The inner lining of the uterus.
Endomitosis The duplication of chromosomes that does not involve division of the nucleus. This results in increased chromosome number within a cell. The chromosomes separate, but the cell does not divide.
Endonucleases Enzymes that hbydrolyse internal regions of nucleic acids.
Endopeptidase An enzyme that hydrolyses a polypeptide chain at an internal peptide linkage.
Endoplasm The inner part of the cytoplasm that is closest to the nucleus.
Endoplasmic reticulum (ER) A system of double membranes in the cytoplasm involved in the synthesis of transported proteins. While rough endoplasmic reticulum contains ribosomes on its surface, the smooth endoplasmic reticulum is devoid of ribosomes.
Endopolyploidy The result of nuclear division without subsequent cytoplasmic division. The polyploids formed in this manner are called endopolyploids. See polyploidy.
Endoprotease An enzyme that cleaves peptide bonds at one or more specific sites in a protein.
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