Lab Techniques: Mcat Study Guide Graded A+

UV-Vis Spectroscopy {Ans: as # conjugated pi bonds increase, energy gap b/w the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) decreases Therefore: light of lower energy is absorbed, producing light with a longer wavelength to be emitted ex: if molecule absorbs green light, will see red!}gram staining {Ans: Purpose: Used to differentiate bacteria into two groups, gram-positive or gram-negative, based on the content of their cell wall sample of bacteria = heat fixed to slide, cystal dye added iodine also added --> binds crystal violet dye, traps it in bacterial cell bacteria washed with alcohol (removes any dye not taken up by bacteria) safranin added as counterstain (bacteria that did not stain w/ crystal violet dye will be visualized)}Northern blotting (RNA) {Ans: Purpose: detection of RNA sequence in sample 1) RNA undergoes gel electrophoresis to separate by size (smaller @ bottom, larger @ top) 4) RNA from gel transferred to nitrocellulose paper --> exposed to radiolabeled RNA probe complementary to strand of interest 5) autoradiography used to ID strand on nitrocellulose paper}chemical shifts in 1H-NMR {Ans: (occurs on the x axis) represents the amount of deshielding of electrons that is caused by