Biochemistry for Medlab Sciences - CHEM 20 - Water PDF

MT T E R M BIOCHEMISTRY FOR MEDLAB SCIENCES CHEM 20 – [LEC] \ YRAD, FLORA...

MT T E R M BIOCHEMISTRY FOR MEDLAB SCIENCES CHEM 20 – [LEC] \ YRAD, FLORA ‘24 ‘25 01 TOPIC 3: WATER A = ball and stick model B = space-filling model OUTLINE C = broken lines represent the Hydrogen bond I Water Introduction A. Polarity D = detailed representation of C; shows electron a. Bond Type cloud b. Molecular Shape E = charges are written in place of atoms (+ for B. Illustrations of Water hydrogen and - for oxygen) II Hydrogen Bonding A. Hydrogen Bonding in Biomolecules III Water as a Solvent HYDROGEN BONDING A. Salt Dissolution water forms hydrogen bonding with each other IV Amphipathic Molecules 1 molecule of water can form 4 hydrogen bonds A. Micelle Formation V Water is Amphoteric ○ 2 = each Hydrogen can be a H-bond donor ○ 2 = while the Oxygen can be a H-bond acceptor in LIQUID WATER WATER ○ hydrogen bonds constantly break and re-form the solvent of biochemical reactions ○ bonds are closer together principle component of most cells in ICE 104.5o = bond angle of water ○ hydrogen bonds are stable ○ water molecules arrange into crystal lattice POLARITY OF WATER structure = more stable ○ they become less dense (less packed) therefore they float in liquid water HYDROGEN BONDING IN BIOMOLECULES Left picture = Proteins ○ hydrogen bonds exist between strands of proteins (ribbon-model) made up of strings of amino acids can dictate how they fold BOND TYPE ○ there is a Hydrogen donor + Hydrogen acceptor the bond between O and H is a polar covalent bond between the protein strands it is because of the differences in electronegativity ○ β-pleated sheets between oxygen and hydrogen occurs between several strands ○ O is more electronegative than H called interstrand hydrogen bonding this results to Hydrogen having a partial positive ○ α-helix charge and Oxygen having a partial negative charge occurs within a single strand called intrastrand hydrogen bonding Right Picture = DNA ○ hydrogen bonding between polymeric strands of nucleotides MOLECULAR SHAPE water has 2 bonding pairs and 2 non-bonding pairs ○ aka electron domains ○ this results to a bent shape thereby making the molecule polar ILLUSTRATIONS OF WATER WATER AS A SOLVENT water is a polar molecule thus it usually dissolves ionic compounds ○ polar dissolves polar = like dissolves like ion-dipole interactions ○ occurs between water (dipole) and the ions (cations and anions) dipole-dipole interactions ○ occurs between water (dipole) and polar organic molecules (i.e. alcohols, ketones) BAQRUILLA | BSMT II 1  TOPIC 3: WATER SALT DISSOLUTION NaCl is an ionic compound and water is a polar molecule = ions are dissociated ○ the Na+ is attracted to the partially negative side of water and the Cl- is attracted to the partially positive side of the water ○ ions then become dislodged from the crystals and are now solvated (when the water surrounds the ion molecules AMPHIPATHIC MOLECULES molecules with both polar and nonpolar portions ○ polar = hydrophilic ○ nonpolar = hydrophobic MICELLE FORMATION when amphipathic molecules are placed in water, they aggregate to form micelles hydrophobic tails are inside the micelle hydrophilic heads are outside the micelle and interact with the external environment application is usually involved with drug delivery ○ nonpolar tails interact with the drug while the polar heads interact with the external environment ○ the drug is essentially coated with an ampipathic molecule WATER IS AMPHOTERIC water is able to act as both a base and an acid it can donate a proton = acid ○ results to OH– it can accept a proton = base ○ results to H3O+ REFERENCES Notes from the discussion/learningmats by: FLORA YRAD Silliman University PowerPoint presentation: Recorded Lecture on WATER TRANSES ARE EXCLUSIVE TO ICLS STUDENTS ONLY. CONTENTS TRANSCRIBED HERE ARE WITHIN THE INTELLECTUAL PROPERTY OF THE UNIVERSITY. SHARING OF TRANSES OUTSIDE THE INSTITUTION IS CONSIDERED AS A BREACH OF ACADEMIC INTEGRITY AND IS SUBJECT TO LEGAL ACTION. PLEASE BE GUIDED. BARQUILLA | BSMT II 2