Copyright 2019 Biology Online Bio 202 Summer 2019 Week 4 Discussion Clarification Lectures 17-23 1. Cell Communication and Signaling Which of the following is a correct statement? A. Calmodulin catalyzes the formation of IP3. B. Receptor tyrosine kinases consist of two polynucleotides that dimerize when activated by a signal molecule. C. Cyclic AMP binds to calmodulin. *D. PIP2 is broken down to IP3 and DAG. Prof. Citovsky’s Response:Calmodulin binds calcium, falsifying option A. Receptor kinases are proteins, not nucleic acids, falsifying option B. Calmodulin binds calcium, not cAMP, falsifying option C. Membrane-anchored PIP2 is indeed cleaved by enzymes, such as phospholipase C, into DAG which remains tethered to the cell membrane, and IP3 which is released into the cell and acts as a second messenger. 2. Redox ReactionThe molecule that functions as the reducing agent in an oxidation-reduction (redox) reaction is the electron donor. This means the molecule that functions as the oxidizing agent, ______ electrons and ______ energy. *A. gains electrons and gains energy. B. loses electrons and loses energy. C. gains electrons and loses energy. D. loses electrons and gains energy. Prof. Citovsky’s Response:In a redox reaction one molecule acts as electron donor and the other as electron acceptor. The donor is oxidized and acts as reducing agent. The acceptor is reduced and acts as oxidizing agent. Also, electrons carry energy and gaining an electron results in gain of energy. Based on this explanation, only answer A is correct whereas answers B-D are wrong. 3. High RatesWhat do cells require to sustain high rates of glycolysis under anaerobic conditions?