| beta particle | <physics, radiobiology> An electron or positron emitted from a radioactive nucleus during beta decay. (09 Oct 1997) |
|---|---|
| genes, intracisternal a-particle | A family of retrovirus-like genetic elements coding for virus-like particles found regularly in early rodent embryos (2-cell to blastocyst stage), but which, under certain circumstances such as DNA hypomethylation, are transcribed in a wide variety of neoplasms, including plasmacytomas, neuroblastomas, rhabdomyosarcomas, teratocarcinomas, and colon carcinomas. (12 Dec 1998) |
| particle | <chemistry> A tiny mass of material. Origin: L. Particula, dim. Of pars = part (18 Nov 1997) |
| particle accelerators | Devices which accelerate electrically charged atomic or subatomic particles, such as electrons, protons or ions, to high velocities so they have high kinetic energy. (12 Dec 1998) |
| particle fluence | <chemistry, radiobiology> at a given point in space, the sum of energies, the number of particles or photons incident during a given time interval on a small sphere centreed at that point, divided by the cross-sectional area of that sphere. It is identical with the time integral of the particle flux density. (16 Dec 1997) |
| charged particle | <radiobiology> A particle which carries a positive or negative electrical charge. In plasma physics, this typically means an ionised atom or molecule, or an electron. (09 Oct 1997) |
| core particle | The group of eight histones (protein molecules which act like spools for DNA to wrap around so that it can be compacted to fit within the nucleus) in the middle of a nucleosome (which is the histone core particle plus the small segment of DNA wrapped around it). (09 Oct 1997) |
| proteinaceous infectious particle | A proposed pathogen composedonly of protein with no detectable nucleic acid and which is responsible for Creutzfeldt-Jakob disease and kuru inhumans and scrapie in sheep. (09 Oct 1997) |
| high energy particle generating unit | A machine capable of providing highly energised radiation for the purposes of radiotherapy treatment. (16 Dec 1997) |
| signal recognition particle | A complex between a 7S RNA and six proteins. SRP binds to the nascent polypeptide chain of eukaryotic proteins with a signal sequence and halts further translation until the ribosome becomes associated with the rough endoplasmic reticulum. One of the SRP proteins (srp54) binds GTP and in association with 7SRNA and srp19 has GTPase activity. (18 Nov 1997) |
| signal recognition particle receptor | Receptor for the signal recognition particle (SRP) found in the membrane of the endoplasmic reticulum. Also called docking protein. Heterodimeric, both protomers having GTP binding capacity, though dissimilar binding sites. Not until the complex of SRP, ribosome, message and nascent polypeptide chain binds to the SRP receptor is the block to further chain elongation released and concurrently the SRP is released, leaving the ribosome attached to the endoplasmic reticulum membrane. Cotranslational transport of the polypeptide delivers it into the lumen of the ER. (18 Nov 1997) |
| submitochondrial particle | Formed by sonicating mitochondria. Small vesicles in which the inner mitochondrial membrane is inverted to expose the innermost surface. (18 Nov 1997) |
| dane particle | <virology> 42 nm spherical particle, the complete infective virion of hepatitis B containing a 27 nm core antigen. (27 Sep 1997) |
| defective interfering particle | An incomplete virus that is unable to replicate and interferes with replication of an infectious virus. (05 Mar 2000) |
| D.I. particle | <abbreviation> Defective interfering particle. (05 Mar 2000) |