BOT 331 Exam 4 Questions With Correct Answers

True/false, if false explain why A protein that binds ATP and transfers a phosphate onto a substrate is called a Protein Phosphatase. - Answer False, a Protein Phosphatase removes phosphates from its substrate; a Protein Kinase transfers phosphates onto its substrate. True/false, if false explain why Indole-3-acetic acid is chemically derived from a nitrogenous base. - Answer False, indole-3-acetic acid, also called auxin, is chemically derived from tryptophan, which is an amino aicd not a nitrogenous base (cytokinin is derived from adenine, which is a nitrogenous base). True/false, if false explain why After absorbing red light, phytochrome changes shape and moves into the nucleus. - Answer True After absorbing red light, phytochrome changes to the Pfr form, which has its nuclear localization sequence on its surface where a protein can bind to it and help move Pfr into the nucleus. Name three different photoreceptors. - Answer Phytochrome, Phototropin and Cryptochrome (there are several other less known photoreceptors) Oscillations in the concentration of cytosolic Ca2+ are a common signaling event in response to a hormone or other input signal. How does a cell generate a Ca2+ oscillation? - Answer In response to signaling, Ca2+ ion channels open that let Ca2+ rush into the cytosol, increasing the concentration of Ca2+ in the cytosol. Ca2+-ATPase pumps move Ca2+ out of the cytosol, either out of the cell or into the lumen of the endoplasmic reticulum, which returns cytosolic Ca2+ to its original concentration. Ion channels open again, and Ca2+ rushes back into the cytosol, and then the Ca2+ is pumped back out, and so on resulting in an oscillation.