For those wanting to know what the new Snapchat emoji symbols mean, there is several different things that they repersent and these emojis have replaced the âBest Friendsâ feature with Friend Emojis smilies.
(plural tetrads) 1  A group of four things. ( 2 chemistry) A tetravalent atom or radical. ( biology) Two pairs of sister chromatids (a dyad pair) aligned in a certain way and often on the equatorial plane during the meiosis process.
Tetracyclines (tetracycline, doxycycline, minocycline, oxtetracycline, ...) are antibiotics which inhibit the bacterial growth by stopping protein synthesis.They have been widely used for the past forty years as therapeutic agent in human and veterinary medicine but also as growth promotor in animal husbandry.everal tetracycline resistance determinants are currently used in molecular biology. The most encountered are the tetA genes of classes A (RP1, RP4 or Tn1721 derivatives), B (Tn10 derivatives) and C (pSC101 or pBR322 derivatives) encoding a tetracycline efflux system.