Chapter 2 Part 2 Power Point (1) PDF
Document Details
Uploaded by FairShofar
Tags
Summary
This document is a presentation on biochemistry concepts, including water, weak bonds, and the generation of order out of chaos, learning objectives, hydrophobic molecules, pH, and buffer systems.
Full Transcript
Chapter 2 Part 2 Water, Weak Bonds, and the Generation of Order Out of Chaos Learning Objectives Be able to understand the Second Law of Thermodynamics and how it applies to the interaction of hydrophobic molecules. Be able to describe the importance of hydrophobic interacti...
Chapter 2 Part 2 Water, Weak Bonds, and the Generation of Order Out of Chaos Learning Objectives Be able to understand the Second Law of Thermodynamics and how it applies to the interaction of hydrophobic molecules. Be able to describe the importance of hydrophobic interactions in formation of membranes and protein folding. Be able to define what pH is and understand the pH scale. Be able to understand the ion product of water and how it is calculated. Be able to define and identify the conjugate acid-base 2.4 Hydrophobic Molecules Cluster Together Second Law of Thermodynamics The total entropy of a system and its surroundings always increases in a spontaneous process. Entropy – measurement of randomness Hydrophobic molecules are nonpolar or uncharged Don’t interact with water Cluster together when in water (hydrophobic effect) By clustering together, they release water molecules increasing the entropy Hydrophobic interactions Spontaneous No energy required to form 2.4 Hydrophobic Molecules Cluster Together Membrane Formation is Powered by the Hydrophobic Effect Phospholipids are amphipathic Head groups are hydrophilic and interact with water along the exterior of the membrane Fatty acids are hydrophobic and cluster together in the interior of the membrane Stabilized by van der Waals interactions Protein Folding is Powered by the Hydrophobic Effect Hydrophobic amino acids of proteins cluster together to help fold the proteins Other interactions with hydrogen bonds and van der Waals aid in folding 2.5 pH Is an Important Parameter of Biochemical Systems pH – measurement of the hydrogen ion concentration of a solution pH = -log[H+] Scale 0-14 pH < 7 is acidic pH = 7 is neutral pH > 7 is basic or alkaline Change in pH can affect ionic bonds and hydrogen bonds Alter shape and function of biomolecules like proteins 2.5 pH Is an Important Parameter of Biochemical Systems Water Ionizes to a Small Extent H2O H+ + OH- Ion Product of Water – Kw Kw = [H+][OH-] = 1.0 x 10-14 M pH = 5 Kw = [1.0 x 10-5M][OH-] = 1.0 x 10-14 M [OH-] = 1.0 x 10-9 M 2.5 pH Is an Important Parameter of Biochemical Systems An Acid is a Proton Donor, Whereas a Base is a Proton Acceptor Conjugate acid-base pair Acid ionizes to form conjugate base Protonation of base yields conjugate acid CH3COOH H+ + CH3COO- Acetic Acid Acetate 2.5 pH Is an Important Parameter of Biochemical Systems Buffers Resist Changes in pH Conjugate acid-base pairs serve as buffers Weak acids are the best buffers near their pKa pKa is pH at which the acid is half dissociated Acid present to give up hydrogen ions if base is added to maintain pH Base present to bind hydrogen ions if acid is added to maintain pH 2.5 pH Is an Important Parameter of Biochemical Systems Why is it important to understand how buffers work? pH changes can affect the structure and function of many molecules, so it is important to understand how to maintain pH in vitro to study these molecules correctly It is important to understand how a cell maintains pH using buffers in vivo to understand what happens when acids are generated as byproduct of metabolism
