BIOCHEM-Module-4_1st-SY-2023-2024_V01.pdf

8/23/24 Learning Objectives MODULE 4: At the end of this module, you should be able to: Wate...

8/23/24 Learning Objectives MODULE 4: At the end of this module, you should be able to: Water and Its Properties 1. 2. Illustrate and explain the chemical structure of water. Explain the different properties of water and give examples. of Biological Importance 3. Appreciate the importance of water biologically and physiologically. C-NMC2LEC First Semester, AY 2024-2025 University of the Assumption University of the Assumption 1 2 Water The Chemical Structure of Water "fundamental molecule for life” Polar molecule: unequal distribution of charge within medium for biological the molecule results in a reactions partial positive charge on the hydrogen atoms and a approx. 60% of the human partial negative charge on body is water the oxygen atom University of the Assumption University of the Assumption 3 4 The Chemical Structure of Water Covalent bond: an intramolecular force within the molecule Hydrogen bond: an intermolecular force between two water molecules University of the Assumption University of the Assumption 5 6 1  8/23/24 Properties of Water 1. High Heat Capacity 1. High heat capacity High heat capacity: refers to the ability of water to absorb and store a 2. High heat of vaporization significant amount of heat energy without experiencing a large increase 3. Cohesion and adhesion in temperature; a result of its molecular structure and the presence of 4. Universal solvent hydrogen bonds between molecules responsible for: § cooling effect: sweating and evaporative cooling § temperature regulation: helps regulate internal body temperature, allowing organisms to adapt to changing environmental conditions University of the Assumption University of the Assumption 7 8 Hydrogen bonds This increased molecular movement, H-bonds are relatively weak also known as kinetic energy, results attractions compared to covalent in a rise in temperature. However, due bonds, which hold the atoms within to the hydrogen bonds constantly each water molecule together. forming and breaking, the temperature However, they are strong enough to increase is more gradual compared to play a crucial role in water's heat substances with weaker or no capacity. When heat is added to hydrogen bonding, like many other water, the extra energy disrupts liquids. Essentially, the heat energy is some of the hydrogen bonds, used to break the hydrogen bonds causing the molecules to move more before the water molecules can gain freely while still remaining in liquid enough kinetic energy to significantly form. raise the temperature. University of the Assumption University of the Assumption 9 10 2. High Heat of Vaporization Conversely, when water loses heat energy, the High heat of vaporization: refers to the significant amount of heat energy that is required to convert a given amount of liquid water into hydrogen bonds form again, releasing energy as the water vapor (steam) at its boiling point, while keeping the temperature molecules slow down. This means that water can constant; a result of the unique molecular structure and hydrogen bonding in water absorb a substantial amount of heat energy without undergoing rapid temperature changes, making it an responsible for: effective heat reservoir. § colling effect § temperature regulation University of the Assumption University of the Assumption 11 12 2  8/23/24 As water transitions from liquid to When water is heated and reaches its boiling vapor during boiling, a substantial point, the molecules gain enough kinetic energy to amount of heat energy is needed to break these hydrogen bonds overcome the attractive forces holding them completely. This energy goes into together in the liquid phase. In the liquid state, disrupting the forces that hold the water molecules are constantly forming and liquid water molecules together and breaking hydrogen bonds with neighboring converting the water into vapor. molecules. These hydrogen bonds are relatively Once these bonds are broken, the strong intermolecular forces. water molecules are free to move more independently in the gas phase. University of the Assumption University of the Assumption 13 14 The high heat of vaporization of water is Cohesion and Adhesion primarily attributed to the strength of hydrogen Cohesion: refers to the attraction between molecules of the same substance; a result of the hydrogen bonds that form between bonds and the high number of these bonds in a neighboring water molecules given volume of liquid water. Compared to leads to several important phenomena: substances with weaker or fewer intermolecular § Surface tension: property of the surface of a liquid that allows it to forces, like most other liquids, water's hydrogen resist an external force, due to the cohesive nature of its molecules bonding network requires a much larger input of § Capillary action: water move against gravity in narrow spaces, such as capillary tubes heat energy to break the bonds and convert it into § Formation of droplets: water form spherical droplets, as the vapor. molecules at the surface of the droplet are attracted to each other, minimizing their surface area University of the Assumption University of the Assumption 15 16 Cohesion Adhesion Adhesion: refers to the attraction between molecules of different substances, results of water’s polar nature and ability to form hydrogen bonds that make it adhere to other polar or charged surfaces leads to several important phenomena: § Capillary action: adhesion, along with cohesion, allows water to "wet" surfaces and climb against gravity in narrow spaces § Meniscus formation: when water is placed in a narrow tube, the curvature of the liquid's surface, “meniscus”, is a result of the Surface Tension: a paper clip Capillary action: without capillary Formation of Droplet: appears balance between cohesive and adhesive forces. made of steel can float on the action, the water level in all tubes would when a water molecule is water surface. The high be the same. Smaller diameter tubes surrounded on all sides by other § Spreading of surfaces: water spreads on surfaces that have a surface tension helps the have more relative surface area inside water molecules, which creates a paper clip (with much higher the tube, allowing capillary action to pull sphere or ball (perfectly round if it degree of polarity, such as glass or paper. density) float on the water. water up higher than in the larger was in outer space) Credits: USGS diameter tubes. Credits: USGS University of the Assumption University of the Assumption 17 18 3  8/23/24 Cohesion and Adhesion Cohesion and Adhesion Meniscus formation: Water molecules are attracted to the molecules in the wall of the glass. And since water molecules like to stick together, when the molecules touching the glass cling to it, other water molecules cling to the molecules touching the glass, forming the meniscus. Credits: USGS University of the Assumption University of the Assumption 19 20 Universal solvent Universal solvent: exceptional ability to dissolve a wide variety of substances; due to its polar nature and hydrogen bonding Water can dissolve a wide range of substances, including salts, sugars, acids, bases, and many organic compounds. When water interacts with ionic compounds, it surrounds individual ions, separating them from each other and allowing them to move freely in solution. For covalent compounds, water's polarity and hydrogen bonding can break apart the molecules and disperse them in the solution. University of the Assumption University of the Assumption 21 22 Universal solvent Universal solvent Biological importance: Biological importance: § Cellular processes: medium for biochemical reactions § Cell structure and function: the fluidity of cell membranes, which § Nutrient transport: water in the bloodstream carries nutrients, are composed of lipids, is influenced by the interactions between minerals, and gases to different parts of the body lipids and water; water also plays a role in maintaining the shape § Waste removal: waste substances are dissolved in water-based and structure of cells bodily fluids and are eventually excreted from the body § Hydration of biomolecules: water molecules surround and interact § Temperature regulation: water's high heat capacity and thermal with biomolecules stabilizing their structures and enabling their conductivity enable it to absorb and distribute heat within the body proper functioning § Metabolic reactions: many biochemical reactions, such as enzyme-catalyzed reactions, occur in water-based environments University of the Assumption University of the Assumption 23 24 4  8/23/24 ------------------------------------------ End of Module 4 ------------------------------------------------------------ Readings and References: Stoker, H. Stephen. Biochemistry. Cengage Learning Asia Pte Ltd, 2016 Hart, Harold, et al. Organic Chemistry: A Brief Course. Cengage Learning Asia Pte Ltd, 2012 Stoker, H. Stephen Exploring General, Organic and Biochemistry. Cengage Learning Asia Pte Ltd, 2013 University of the Assumption 25 5