Chemical and Physical Properties of Water Unit 1 PDF

Chemical and Physical Properties of Water Unit 1 1 Water is essential to ALL life on earth! Without water, life as we know it would not exist Water is the most abundant compound in living things. Most organisms are 60-80%water Water is used to transport materials...

Chemical and Physical Properties of Water Unit 1 1 Water is essential to ALL life on earth! Without water, life as we know it would not exist Water is the most abundant compound in living things. Most organisms are 60-80%water Water is used to transport materials (blood, sap), regulate temperature, and to produce cell products like saliva, tears, sweat, stomach acids, etc. 2 Water can also be used to provide support and structure to body parts (jellyfish) and for movement (hydraulic systems such as those found in worms and starfish) 3  Chemistry of Water Water is forms molecules by 2 hydrogen atoms that are bonded to a single oxygen atom: H2O. Molecules are formed when elements are combined by covalent bonds. The oxygen and hydrogen atoms are held together because they “share” electrons 4 5 These “shared electrons” form a covalent bond The water molecule has a shape like a widened “V” with 104.5 degree angle. 6 Because the oxygen atom is much larger than the hydrogen atoms, it tends to “share” the electrons a little more than the hydrogen atoms do The unequal sharing of the electrons causes water to have a slight electrical charge on each end. 7 The oxygen end is negative, and the hydrogen end is positive Polar molecule – has an electrical charge on each end; water is a polar molecule Because water is polar, it can dissolve many substances. It is considered to be the universal solvent. 8 9  Hydrogen Bonds The slight electrical charges on each end of a water molecule helps to attract other molecules, and gives water many of its unique properties. 10 The slight bonds that form between the negative end of one water molecule and the positive end of another water molecule are called hydrogen bonds. 11  Hydrogen Bonding = Negative (Oxygen) pole of a water molecule is attracted to the positive (Hydrogen) pole of another water molecule It is a weak attraction but does give water some cool properties Molecules that are not polar will not experience hydrogen bonding 13 14 15  Some unique properties of water 1)High Boiling Point = 100oC (212oF) 2)Solid form is less dense than liquid form (ice floats in liquid water) 3) Cohesion = water molecules wanting to stay together, keeps water in puddles instead of widespread droplets or molecules 4) Adhesion = water molecules wanting to stay connected to other polar surfaces (glass) Cohesiveness – attraction between water molecules; causes water molecules to stick together Viscosity –due to cohesion between water molecules; property by which water tends to resist objects entering the water (surface tension). 17 Surface tension 18 19 Adhesiveness – causes water to stick to other materials The adhesive properties of water cause capillary action-tendency of water to creep up this tubes. This is how plants rooks take in water, and the meniscus is formed in a glass graduated cylinder. Both cohesiveness and adhesiveness are due to the hydrogen bonds that form between water molecules and between water molecules and other substances ☺ 20 21 Solvent – substance that dissolves other substances. Water is an excellent solvent because of its hydrogen bonds Ions and other polar substances such as sugar are easily dissolved by water ☺ 22  Properties of Water 5. Water organizes nonpolar molecules. - hydrophilic: “water-loving” -hydrophobic: “water-fearing” - Water causes hydrophobic molecules to aggregate or assume specific shapes. 6. Water can form ions. H2O 🡪 OH-1 + H+1 hydroxide ion hydrogen ion 23 Two oppositely charged ions attract each other and form very powerful bonds: ionic bonds Na+ + Cl- Na+Cl- (reactants) (products) Sodium (positive ion) plus chlorine (negative ion) forms sodium chloride (table salt) Na + Cl Ionic Bond NaCl Ionic Bond 24 The bonds formed by these electrical charges are easily broken by the polar water molecules; that is why salt dissolves in water. When salt is dissolved in water it forms a solution because all of the particles are evenly distributed. 25 Gases such as oxygen, carbon dioxide, and nitrogen are also easily dissolved into water Oxygen is essential for most organisms, and the amount of carbon dioxide dissolved in the water affects the pH of the water Soft drinks Global Warming Makes Ocean Acidic 26  Physical Properties of Water On earth, water exists in 3 physical states 1. Solid – ice – below 32°F, 0°C 2. Liquid – water – between 32°F - 212°F 0°C - 100°C 3. Gas – vapor – above 212°F, 100°C ☺ 27 Ice, water, vapor 28 Ice, water, vapor 29  Properties of Water 1. Water has a high specific heat. - A large amount of energy is required to change the temperature of water. 2. Water has a high heat of vaporization. - The evaporation of water from a surface causes cooling of that surface. 30  Properties of Water 3. Solid water is less dense than liquid water. - Bodies of water freeze from the top down. 4. Water is a good solvent. - Water dissolves polar molecules and ions. 31 Temperature is a measure of the amount of kinetic energy in a substance Kinetic energy refers to how much the atoms in a substance are “bouncing around” A Thermometer is a molecular speedometer. ☺ 32 As the kinetic energy increases, the distance between the molecules increases and the temperature goes up (expands) As the kinetic energy decreases, the distance between molecules decreases and the temperature goes down (shrinks) ☺ 33 Density – describes the distance between molecules in a substance Often expressed as Mass/Volume 34 Generally, the lower the temperature, the greater the density Water is unique because its density-temperature relationship does not follow normal rules at low temperatures Water breaks away from “normal” behavior at about 4°C (36°F) ☺ 35 At that temperature and lower, water actually becomes slightly less dense This is due to the way that water molecules “line up” as the water molecules begin to repel each other as they come very close together This is the reason that ice floats; it is actually less dense than liquid water ☺ 36 If water behaved like “normal” substances, lakes and oceans would freeze from the bottom up (because the denser cold water would sink) Life as we know it would not exist, as most of the earth’s water would remain frozen most of the year ☺ 37 Solid 38 Liquid 39 Gas 40 In the winter time, the bottom of a frozen lake will have a layer of water that is around 36°F. Since water is most dense at this temperature, this prevents all but the most shallow of lakes and ponds from freezing solid ☺ 41  Temperature & Density in Solutions Since the distance between molecules increases as the temperature increases, warmer water can hold more dissolved substances than colder water Example: hot water can dissolve more salt than cold water ☺ 42 Oxygen molecules near the surface “bounce out” into the atmosphere The water molecules don’t “bounce out” as quickly as the oxygen molecules because of cohesion ☺ 43 Oxygen molecules diffuse from deeper water to replace those that escape near the surface, where they also heat up and “bounce out” This causes the entire water mass to lose oxygen when the temperature rises ☺ 44 The role of pH in Agriculture and Food Gellie B. Lam-an Introduction of pH in Agriculture and Food What is pH? - pH measures the acidity or alkalinity of a solution, soil, or food product. - It influences nutrient availability in soils, plant health, and food preservation. Importance of pH: - In agriculture, pH affects crop growth, soil microbiology, and nutrient absorption - In food, pH influences taste, safety, texture, and shelf life. pH in Agriculture: Soil Health Soil pH: Neutral pH (6.5-7.5): Optimal for most crops. Acidic Soils (pH < 6.5): Common in high rainfall areas, may lead to nutrient deficiencies and metal toxicity. Alkaline Soils (pH > 7.5): Often found in arid regions, can limit nutrient availability (e.g., phosphorus and iron). pH in Agriculture: Soil Health Impact on Nutrients: pH affects the solubility of soil nutrients like nitrogen, phosphorus, potassium, and trace elements. pH and Crop Growth Optimal pH for Different Crops: Acidic Soil Lovers: Blueberries, cranberries, potatoes (pH 4.5-6.0). Neutral pH Crops: Corn, soybeans, most vegetables (pH 6.0-7.0). Alkaline-Tolerant Crops: Asparagus, beets, cabbage (pH 7.0-8.0). pH and Crop Growth Impact of Incorrect pH: Too Acidic: Reduces calcium, magnesium, and phosphorus availability. Too Alkaline: Limits iron, manganese, and phosphorus uptake. Managing Soil pH in Agriculture Acidic Soils: Solution: Apply lime (calcium carbonate) to neutralize acidity and raise pH. Alkaline Soils: Solution: Add sulfur or sulfuric acid to reduce pH and correct nutrient deficiencies. Soil Testing: Regular pH testing helps farmers optimize soil conditions for crop growth. pH in Irrigation Water Water pH: Affects soil pH over time. Acidic Water (pH < 6.0): Can lead to long-term soil acidification. Alkaline Water (pH > 8.0): Can cause salt buildup and decrease soil fertility. Adjusting Water pH: Farmers may adjust water pH by adding acidifiers or alkaline agents to ensure soil health. pH in Food Production Importance of pH in Food: pH affects food flavor, texture, safety, and shelf life. Acidic Foods: pH < 4.6 helps preserve food by inhibiting microbial growth (e.g., pickles, yogurt). Examples: Vinegar (pH ~2.5), Lemon juice (pH ~2), Tomatoes (pH ~4.2). pH in Food Production Alkaline Foods: pH > 7, less common but can be found in some fermented foods (e.g., natto, alkaline noodles). pH and Food Safety pH in Food Preservation: Low pH inhibits the growth of harmful bacteria like Clostridium botulinum. Fermentation: Naturally lowers pH, as in yogurt, sauerkraut, and kefir, extending shelf life. pH and Food Safety pH in Meat and Dairy: Proper pH levels ensure safe processing and storage. Milk: pH 6.5-6.7 when fresh, becomes more acidic as it spoils. pH and Flavor in Food Taste and Acidity: pH influences the taste profile of foods. Acidic: Foods like citrus, vinegar, and fermented products are tangy due to their low pH. Alkaline: Some foods, such as baking soda, neutralize acids, affecting both flavor and texture. pH and Flavor in Food pH and Cooking: Adjusting pH can change how ingredients interact, such as in baking, where acidic ingredients activate baking soda. pH in Fermentation Fermented Foods: ○ Bacteria and yeast convert sugars into acids, reducing pH. ○ Common fermented foods like kimchi, yogurt, and sauerkraut depend on maintaining low pH for flavor and preservation. Fermentation Process: ○ Starts with a neutral or slightly acidic pH, but as fermentation progresses, pH drops significantly (e.g., yogurt pH ~4.0). Buffer Systems in Food Buffering Capacity: Some foods, like dairy products, have a natural buffer system, resisting pH changes during processing. Importance of Buffers in Processed Foods: Buffers help stabilize the pH of food products, ensuring consistency in flavor and texture. pH and Food Quality Quality Indicators: pH is a key parameter for determining the freshness and quality of certain foods. Examples: Cheese (pH changes during aging), Wine (pH affects fermentation and taste), Canned foods (pH influences safety). pH Monitoring in Food Production: Used in quality control to maintain consistent product standards. Conclusion Agriculture: ○ pH affects soil health, nutrient availability, crop growth, and irrigation management. ○ Regular pH testing and adjustments are vital for sustainable farming. Food: ○ pH plays a crucial role in food safety, flavor, texture, and preservation. ○ Monitoring and controlling pH ensures quality and extends the shelf life of food products. Introduction to Biochemistry in Agriculture and Food Biochemistry - is concerned with chemical and physicochemical processes that present inside the living organism. Agricultural biochemistry - crucial for sustainable farming and global food security. By understanding biochemical processes in plants, animals and microorganisms. It can optimize crop production, reduce environmental impacts, and enhance food quality. The role of biochemical processes in Agriculture Plant Metabolism, nutrient uptake, photosynthesis - can develop innovative strategies to optimize growth conditions, improve resistance, and enhance overall plant health. Biofuel Production - by optimizing these pathways through genetic engineering and metabolic engineering techniques, researchers aim to develop energy crops and microbial systems that can efficiently convert biomass into renewable fuels. Genetic engineering - By introducing foreign genes or silencing existing ones, researchers can enhance crop resistance to pests, diseases, and environmental stresses. It also enables the production of crops with enhanced nutritional content. Biochemical approaches for sustainable agriculture Biofertilizers and Biostimulants - optimizing nutrient management through the application of biofertilizers and biostimulants. It can also assists in the development of natural pesticides derived from plant metabolites, minimizing the ecological impact on beneficial organisms and reducing chemical residues in harvested produce. Post-harvest - Biochemistry provides tools to address this issue by studying the mechanisms underlying crop deterioration and spoilage. By understanding the biochemical processes involved in ripening, senescence, and microbial decay, scientists can develop techniques to extend the shelf life of harvested produce Carbohydrates Carbohydrates are essential organic molecules involved in numerous biological processes, particularly related to energy storage, cell structure, and molecular signaling. Their roles are essential in maintaining life functions, and they interact with other biomolecules like proteins, lipids, and nucleic acids. Classification of Carbohydrates in Biochemistry: 1. Monosaccharides: These are the simplest form of carbohydrates, consisting of a single sugar unit. - Examples include glucose, fructose, and galactose. Glucose, in particular, is a central energy molecule in metabolism. 2. Oligosaccharides: Consist of 2-10 monosaccharide units. Disaccharides (like sucrose, lactose, and maltose) are the simplest oligosaccharides. 3. Polysaccharides: These are long chains of monosaccharides linked by glycosidic bonds. Common examples include starch (plant energy storage), glycogen (animal energy storage), and cellulose (structural component in plant cell walls). Carbohydrate Synthesis in Plants primarily occurs through the process of photosynthesis, where plants convert light energy into chemical energy stored in the form of glucose (a carbohydrate). This process takes place in the chloroplasts of plant cells and involves two main stages: 1. Light-dependent reactions 2. Calvin Cycle. Here's a detailed look at the stages: 1. Light-Dependent Reactions: Location: Occur in the thylakoid membranes of the chloroplasts. Process: ○ Chlorophyll, the green pigment in plants, absorbs sunlight. ○ This energy is used to split water molecules (H₂O) into oxygen (O₂), protons (H⁺), and electrons. ○ The released oxygen is expelled as a byproduct. ○ Energy from the light is used to produce ATP (adenosine triphosphate) and NADPH (nicotinamide adenine dinucleotide phosphate), both of which are high-energy molecules that will be used in the next stage. 2. Calvin Cycle (Light-Independent Reactions):  Location: Occurs in the stroma of the chloroplasts. Process: ○ Carbon dioxide (CO₂) from the atmosphere is taken up by the plant. ○ Using the energy stored in ATP and NADPH from the light-dependent reactions, CO₂ is fixed into organic molecules in a series of reactions. ○ These reactions result in the production of glucose (C₆H₁₂O₆), a simple sugar that serves as a carbohydrate. 3. Glucose Storage: Starch Formation: The glucose produced can be stored in the form of starch, a polysaccharide. Starch serves as a long-term energy reserve for the plant and can be stored in roots, stems, seeds, or leaves. Cellulose: Some of the glucose is used to form cellulose, which provides structural support in the plant's cell walls. Summary of the Photosynthesis Process: Input: Light energy, water (H₂O), and carbon dioxide (CO₂). Output: Oxygen (O₂) and glucose (C₆H₁₂O₆). Function: The glucose synthesized through photosynthesis is either stored as starch for energy or used immediately to fuel cellular activities. The process of carbohydrate synthesis is fundamental for plant growth and development, as it forms the basis for energy production in plants and, subsequently, in the organisms that consume them​ Carbohydrate metabolism in animals involves a series of biochemical processes by which carbohydrates, primarily glucose, are broken down to produce energy. This energy is used to power cellular functions and maintain bodily activities. The major pathways: 1. Glycolysis 2. Krebs cycle (also called the citric acid cycle) 3. Electron transport chain. Here's a detailed look at the stages: 1. Glycolysis:  Location: Cytoplasm of the cell. Process: ○ Glycolysis is the first step in glucose metabolism. It involves the breakdown of one glucose molecule (C₆H₁₂O₆) into two molecules of pyruvate. ○ This process generates a small amount of energy in the form of ATP (2 molecules per glucose) and also produces NADH (2 molecules), a carrier of electrons for later stages. ○ Glycolysis does not require oxygen, making it an anaerobic process. Products: 2 ATP, 2 NADH, and 2 pyruvate molecules. 2. Krebs Cycle (Citric Acid Cycle): Location: Mitochondria. Process: ○ If oxygen is present, pyruvate enters the mitochondria, where it is converted into acetyl-CoA, which then enters the Krebs cycle. ○ The Krebs cycle is a series of enzyme-driven reactions that further break down acetyl-CoA, producing ATP, NADH, FADH₂ (another electron carrier), and CO₂ as a waste product. ○ This cycle generates high-energy molecules needed for the next stage of energy production. Products: 2 ATP, 6 NADH, 2 FADH₂, and CO₂ (per glucose molecule). 3. Electron Transport Chain (ETC): Location: Inner membrane of the mitochondria. Process: ○ NADH and FADH₂ produced during glycolysis and the Krebs cycle donate electrons to the electron transport chain. ○ These electrons are passed along a series of protein complexes, releasing energy to pump protons (H⁺) across the inner mitochondrial membrane, creating a proton gradient. ○ The flow of protons back across the membrane drives the production of a large amount of ATP through a process called oxidative phosphorylation.  ○ At the end of the electron transport chain, oxygen serves as the final electron acceptor, combining with protons to form water. Products: Approximately 32-34 ATP molecules (per glucose), and water. Overall ATP Yield: From one molecule of glucose, about 36-38 molecules of ATP are produced through the combined processes of glycolysis, the Krebs cycle, and the electron transport chain. This energy is essential for various cellular activities, such as muscle contraction, maintaining body temperature, and driving biochemical reactions. Roles of Carbohydrates in Plant Physiology 1. Energy Storage: Starch: The main form of carbohydrate storage in plants is starch, a polysaccharide made up of long chains of glucose molecules. Starch is stored in various plant tissues, such as roots, seeds, and leaves, and serves as a readily available source of energy for growth and metabolism when needed. Carbohydrates act as signaling molecules that regulate various aspects of plant growth, development, and differentiation. Sucrose, in particular, functions as both an energy source and a signal that regulates the expression of genes involved in growth. 2. Structural Support: Cellulose: One of the most important carbohydrates for structural integrity in plants is cellulose, a polysaccharide composed of glucose units linked by β-1,4-glycosidic bonds. Cellulose forms the main component of the plant cell wall, providing rigidity and strength. ○ Function: Cellulose enables plant cells to maintain their shape and withstand internal turgor pressure, which is essential for plant stability and growth. 3. Signaling Carbohydrates like chitin oligosaccharides or β-glucans derived from pathogens (such as fungi) can be recognized by plant receptors, triggering a defense response. Carbohydrates can be involved in plant defense mechanisms and responses to environmental stress. Certain carbohydrates, such as oligosaccharides, act as signaling molecules that trigger defense responses against pathogens. Roles of Carbohydrate in Animal Physiology 1. Energy Source: Glucose, a simple sugar, is the most important carbohydrate for energy production in animals. It is used in cellular respiration to produce ATP (adenosine triphosphate), the energy currency of cells. Glycolysis, the Krebs cycle, and the electron transport chain are metabolic pathways that convert glucose into ATP. Energy Use: ○ Muscle cells rely heavily on glucose during physical activity. ○ The brain is almost entirely dependent on glucose for energy, as neurons cannot efficiently use fats for fuel. ○ Red blood cells also rely on glucose because they lack mitochondria and thus cannot metabolize fats or proteins. 2. Structural Components: Certain carbohydrates serve structural functions in animals. Glycosaminoglycans (GAGs), such as hyaluronic acid, chondroitin sulfate, and heparin, are long polysaccharides that play key roles in the structure and function of connective tissues. Role in Connective Tissue: ○ GAGs are essential components of cartilage, skin, and extracellular matrix, providing structural support, lubrication, and shock absorption. ○ For example, hyaluronic acid helps maintain the viscosity and elasticity of synovial fluid in joints. 3. Cell Recognition and Communication: Glycoproteins and glycolipids, which are carbohydrates attached to proteins and lipids, are key components of cell membranes. They play crucial roles in cell-cell recognition, signaling, and immune responses. Cell Recognition: Carbohydrate molecules on the cell surface act as markers that enable cells to identify each other. This is vital for immune function, as it helps the body distinguish between its own cells and foreign invaders. Immune Response: Carbohydrates on the surfaces of pathogens can be recognized by the immune system, triggering a defense response. 4. Brain Function: The brain is highly dependent on glucose as its primary energy source because it cannot efficiently metabolize fats for energy.  Glucose Deprivation: When blood glucose levels fall too low (hypoglycemia), cognitive functions are impaired, leading to symptoms like confusion, dizziness, and in severe cases, loss of consciousness.