Hydrogen Bond Lab Report

Name: RETUERMA, Jemmari R. Date: July 10, 2015

Section: BSED 2A Title: Assignment no. 2

I. How can HYDROGEN BOND leads to the 5 properties of water?

A hydrogen bond is an attraction between a pair of electronegative atoms involving a hydrogen atom located between them. Hydrogen bonds are responsible for the life-giving properties of water. Water is one of the most unique molecules known to man and also one of the most important in biological system. Water is the universal solvent. The two characteristic of water are Cohesion the molecules tend to stick each other in a regular pattern and Surface

The prestin molecule way patented by its discoveries in 2003. Prestin is the motor protein of cochlear outer hair cells. The outer and inner hair cells of the mammalian cochlea perform different functions. In response to changes in membrane potential, the cylindrical outer hair cell rapidly alters its length and stiffness. These mechanical changes, driven by putative molecular motors, are assumed to produce amplification of vibrations in the cochlea that are transduced by inner hair cells. Here we have identified an abundant complementary DNA from a gene, designated Prestin, which is specifically expressed in outer hair cells. Regions of the encoded protein show moderate sequence similarity to pendrin and related sulphate/anion transport proteins. Voltage-induced shape changes can be elicited in cultured human kidney cells that express prestin. The mechanical response of outer hair cells to voltage change is accompanied by a 'gating current', which is manifested as nonlinear capacitance. We also demonstrate this nonlinear capacitance in transfected kidney cells. We conclude that prestin is the motor protein of the cochlear outer hair cell. Intrinsic voltage sensing In this model of intrinsic voltage-sensing, the movement of ions generates a nonlinear capacitance (NLC). Based upon the generated voltage and the depolarized or hyperpolarized state of the cell, prestin will transition through two distinct steps, representing the three-state model of prestin modulation. Experiments show that with increasing depolarizing stimuli, prestin transitions from an elongated state to an intermediate state to a contracted state, increasing its NLC. Under hyperpolarizing conditions, NLC decreases and prestin transitions back to its elongated state. Of significance, increased membrane tension as characterized by prestin elongation decreases the chloride