Click on a lesson name to select. Chapter 6 Chemistry in Biology Section 1: Atoms, Elements, and Compounds Section 2: Chemical Reactions Section 3: Water and Solutions Section 4: The Building Blocks of Life
6.1 Atoms, Elements, and Compounds Chapter 6 Chemistry in Biology See into chem for 6.1
Reactants and Products A chemical reaction is the process by which atoms or groups of atoms in substances are reorganized into different substances. 6.2 Chemical Reactions Clues that a chemical reaction has taken place include the production of heat or light, and formation of a gas, liquid, or solid. Chemistry in Biology Chemical reaction Physical reaction Chapter 6
Chemical Equations Chemistry in Biology Chemical formulas describe the substances in the reaction and arrows indicate the process of change. Reactants are the starting substances, on the left side of the arrow. Products are the substances formed during the reaction, on the right side of the arrow. 6.2 Chemical Reactions Chapter 6
Q Label the reactants and products as you write out the equation for the complete combustion of glucose (C6H12O6). Label reactants and Products.
Glucose and oxygen react to form carbon dioxide and water. Chemistry in Biology 6.2 Chemical Reactions Chapter 6
Chemistry in Biology Balanced Equations The law of conservation of mass states matter cannot be created or destroyed. The number of atoms of each element on the reactant side must equal the number of atoms of the same element on the product side. 6.2 Chemical Reactions Chapter 6
Chemistry in Biology A catalyst is a substance that lowers the activation energy needed to start a chemical reaction. It does not increase how much product is made and it does not get used up in the reaction. Enzymes 6.2 Chemical Reactions Chapter 6
Q Explain how enzymes speed up reactions (use “activation energy” in answer):
Chemistry in Biology The activation energy is the minimum amount of energy needed for reactants to form products in a chemical reaction. Energy of Reactions 6.2 Chemical Reactions Chapter 6
Enzymes are proteins meant to function best in certain conditions Enzymes have a preferred: Temperature Salt concentration pH If you put them in non ideal situations they will not work. They become “denatured”
In the cell, there is not enough heat energy available to routinely achieve the activation energy needed for these reactions Enzymes are required to get these reactions to proceed
Enzymes speed reactions by lowering E A. –The transition state can then be reached even at moderate temperatures. Enzymes do not change delta G. –It hastens reactions that would occur eventually. –Because enzymes are so selective, they determine which chemical processes will occur at any time.
Q Define Exothermic and give an example of this type of reaction. Show a graph of energy vs time for exothermic reactions.
Chemistry in Biology This reaction is exothermic and released heat energy. The energy of the product is lower than the energy of the reactants. 6.2 Chemical Reactions Chapter 6
Chemical reactions can be classified as either; 1. exergonic or 2. endergonic based on free energy. An exergonic reaction proceeds with a net release of free energy. ex.’s Burning paper, burning glucose Exergonic reactions are spontaneous. Does paper burn spontaneously?
Q Define Endothermic and give an example of this type of reaction. Show a graph of energy vs time for endothermic reactions.
Chemistry in Biology This reaction is endothermic and absorbed heat energy. The energy of the products is higher than the energy of the reactants. 6.2 Chemical Reactions Chapter 6
An endergonic reaction is one that absorbs free energy from its surroundings. –Endergonic reactions store energy, –reaction are nonspontaneous. Ex.; building a protein or DNA molecule, photosynthesis
Chemistry in Biology The reactants that bind to the enzyme are called substrates. The specific location where a substrate binds on an enzyme is called the active site. 6.2 Chemical Reactions Chapter 6
Chemistry in Biology Factors such as pH, temperature, and other substances affect enzyme activity. 6.2 Chemical Reactions Chapter 6 The active site changes shape and forms the enzyme-substrate complex, which helps chemical bonds in the reactants to be broken and new bonds to form.
Does boiling affect Pectinase’s ability to break down cell walls?
Renin Lab Renin is an enzyme which cuts the milk protein Casein in two. A whole Casein prot stays dissolved in milk, but the smaller pieces clump up and fall out of solution. These become cheese curds! Rennin is obtained through scraping the lining of calf stomachs.
The lab problem: “How does temperature affect rennin’s ability to make cheese curds?” Temps to use: -Room temp -Refrigerator -Incubator at body temp -Boiling water bath For hypothesis: address how you think rennin will do at each of these temps
Water’s Polarity 6.3 Water and Solutions Chemistry in Biology Molecules that have an unequal distribution of charges are called polar molecules. Polarity is the property of having two opposite poles. A hydrogen bond is a weak interaction involving a hydrogen atom and a fluorine, oxygen, or nitrogen atom. Chapter 6
Q Draw a diagram of two water molecules and indicate: a.The polar covalent bonds b.The hydrogen bond
Q Describe 3 of water’s “weird” properties: What causes these weird properties?
Water has a variety of unusual properties because of attractions between water molecules. –Oxygen takes on a slightly negative charge –Hydrogen takes on a slightly positive charge –Slightly positive regions of one molecule are attracted to the slightly negative regions of nearby molecules, forming a hydrogen bond.
Hydrogen bonds hold water molecules together, a phenomenon called cohesion. (water to water) Cohesion among water molecules plays a key role in the transport of water against gravity in plants
Adhesion is clinging of water molecules to molecules of another substance Water sticking to glass Capillary action is due to adhesion
Surface tension, (a measure of the force necessary to stretch or break the surface of a liquid), is related to cohesion. –Water has a greater surface tension than most other liquids because hydrogen bonds among surface water molecules resist stretching or breaking the surface. Water behaves as if covered by an invisible film. Some animals can walk on water’s surface
Water stabilizes air temperatures by absorbing heat from warmer air and releasing heat to cooler air. Water can absorb or release relatively large amounts of heat with only a slight change in its own temperature. Water moderates temperatures on Earth
Water stabilizes temperature because it has a high specific heat. The specific heat of a substance is the amount of heat that must be absorbed or lost for 1g of that substance to change its temperature by 1 o C. –By definition, the specific heat of water is 1 cal per gram per degree Celcius or 1 cal/g/ o C. Water has a high specific heat compared to other substances. –For example, ethyl alcohol has a specific heat of 0.6 cal/g/ o C. –The specific heat of iron is 1/10th that of water.
Water resists changes in temperature because it takes a lot of energy to speed up its molecules. Water’s high specific heat is due to hydrogen bonding (Things get hotter when their molecules vibrate faster- Water resists vibrating faster because the molecules are connected to one another –takes a lot of heat to get all water molecules vibrating faster) Water = little vib = cool Non-Polar “stuff” = hot
The transformation of a molecule from a liquid to a gas is called vaporization or evaporation. –This occurs when the molecule moves fast enough that it can overcome the attraction of other molecules in the liquid. Heating a liquid increases the average kinetic energy and increases the rate of evaporation. Yippe! Free at last!
Heat of vaporization is the quantity of heat that a liquid must absorb for 1 g of it to be converted from the liquid to the gaseous state. –Water has a relatively high heat of vaporization (high boiling point), requiring about 580 cal of heat is to evaporate 1g of water at room temperature. –This is because hydrogen bonds must be broken before a water molecule can evaporate from the liquid. Water’s high heat of vaporization moderates climate by absorbing heat in the tropics via evaporation and releasing it at higher latitudes as rain.
As a liquid evaporates, the surface of the liquid that remains behind cools - evaporative cooling. –This occurs because the most energetic molecules are the most likely to evaporate, leaving the lower kinetic energy molecules behind. Evaporative cooling moderates temperature in lakes and ponds and prevents terrestrial organisms from overheating. Evaporation of water from the leaves of plants or the skin of humans removes excess heat. Mike Tyson would be much less effective at biting ears off people if not for the cooling effect of sweat
Q When is water at its maximum density? Name a consequence of this that is important to Biology
Water is unusual because it is less dense as a solid than as a liquid. –Most materials contract as they solidify, but water expands. –At temperatures above 4 o C, water behaves like other liquids, expanding when it warms and contracting when it cools. –Water begins to freeze when its molecules are no longer moving vigorously enough to break their hydrogen bonds. Oceans and lakes don’t freeze solid because ice floats ***Max density of water is at 4 o C***
–When water reaches 0 o C, water becomes locked into a crystalline lattice with each molecule bonded to to the maximum of four partners. –Ice is about 10% less dense than water at 4 o C.
Therefore, ice floats on the cool water below. This oddity has important consequences for life. –If ice sank, eventually all ponds, lakes, and even the ocean would freeze solid. –During the summer, only the upper few inches of the ocean would thaw. –Instead, the surface layer of ice insulates liquid water below, preventing it from freezing and allowing life to exist under the frozen surface.
**Summary of Water’s Unique Properties** Cohesion === surface tension Adhesion === transpiration (water up in trees) High specific heat === moderates temp changes High boiling point === liquid form on earth surface High Heat of evap. ====good evaporative coolant Solid less dense than liquid===fish happy Good solvent==cells are bags of water with solutes in
Any substance that has an affinity for water is hydrophilic. –These substances are dominated by ionic or polar covalent bonds.
Substances that have no affinity for water are hydrophobic. –These substances are dominated by non-ionic and nonpolar covalent bonds. –Because there are no consistent regions with partial or full charges, water molecules cannot form hydrogen bonds with these molecules. –Hydrophobic molecules are major ingredients of cell membranes. (How does water get across then?) Think hydrocarbons like oil, gas, fats
MacGyver pH lab The scenario: terrorists have captured a group of daycare children. They are threatening to harm the children unless you tell them the pH of their solution. Upset that you forgot to put your litmus paper in your pocket this AM as you usually do, you begin to form a plan…
Q Matching: match these Kool- Aid related terms (order mixed up for test: water, what you drink, the powder) ___Solution ___solvent ___solute
A liquid that is a completely homogeneous mixture of two or more substances is called a solution. –A sugar cube in a glass of water will eventually dissolve to form a uniform mixture of sugar and water. The dissolving agent is the solvent and the substance that is dissolved is the solute. –In our example, water is the solvent and sugar the solute. In an aqueous solution, water is the solvent. Water is not a universal solvent, but it is very versatile because of the polarity of water molecules. Water is the solvent of life
Chemistry in Biology Solution = Homogenous Mixture of a solvent and a solute A solvent is a substance in which another substance is dissolved. A solute is the substance that is dissolved in the solvent. Food coloring dissolved in water forms a homogenous mixture. 6.3 Water and Solutions Chapter 6
Chemistry in Biology Heterogeneous Mixtures In a heterogeneous mixture, the components remain distinct. A salad is a heterogeneous mixture. 6.3 Water and Solutions Chapter 6
Q What is the definition of an acid? Of a base?
Chemistry in Biology Substances that release hydrogen ions (H + ) when dissolved in water are called acids. Substances that absorb H+ ions are called bases. Acids and Bases 6.3 Water and Solutions Chapter 6
Q What is pH a measure of? As the concentration of H+ increases, what happens to the pH value?
Chemistry in Biology The measure of concentration of H + in a solution is called pH. Acidic solutions have pH values lower than 7. Basic solutions have pH values higher than 7. pH and Buffers 6.3 Water and Solutions Chapter 6
Q What is a good approximation for the pH’s of these things: a.Water: b.Hydrochloric acid (HCl – strong acid): c.Sodium Hydroxide (NaOH –strong base):
Q In what specific way do buffers help you to maintain pH homeostasis?
Chemistry in Biology Buffers are mixtures that can react with acids or bases to keep the pH within a particular range. 6.3 Water and Solutions Chapter 6
Chemical processes in the cell can be disrupted by changes to the H + and OH - concentrations away from their normal values near pH 7. To maintain cellular pH values at a constant level, biological fluids have buffers. Buffers resist changes to the pH of a solution when H + or OH - is added to the solution.
How buffers work: Add H+ === H+ soaked up by H+ acceptor and pH doesn’t change Take away H+ === H+ donor pulled apart to add more H+
Problem: Is “MacGyver juice” an accurate indicator of pH? Design PHEOC exp to test with all sections labelled. Work in lab groups.
See sep macromol notes for 6.4 6.4 The Building Blocks of Life Chemistry in Biology Chapter 6
Carbon has four electrons in its outermost energy level. One carbon atom can form four covalent bonds with other atoms. Chemistry in Biology Carbon compounds can be in the shape of straight chains, branched chains, and rings. 6.4 The Building Blocks of Life Chapter 6
Macromolecules Chemistry in Biology Carbon atoms can be joined to form carbon molecules. Macromolecules are large molecules formed by joining smaller organic molecules together. Polymers are molecules made from repeating units of identical or nearly identical compounds linked together by a series of covalent bonds. 6.4 The Building Blocks of Life Chapter 6
Chemistry in Biology Carbohydrates Compounds composed of carbon, hydrogen, and oxygen in a ratio of one oxygen and two hydrogen atoms for each carbon atom—(CH 2 O) n 6.4 The Building Blocks of Life Chapter 6
Chemistry in Biology Two monosaccharides joined together form a disaccharide. Longer carbohydrate molecules are called polysaccharides. 6.4 The Building Blocks of Life Chapter 6 Values of n ranging from three to seven are called simple sugars, or monosaccharides.
Chemistry in Biology Lipids Molecules made mostly of carbon and hydrogen A triglyceride is a fat if it is solid at room temperature and an oil if it is liquid at room temperature. 6.4 The Building Blocks of Life Chapter 6
Chemistry in Biology Lipids that have tail chains with only single bonds between the carbon atoms are called saturated fats. Lipids that have at least one double bond between carbon atoms in the tail chain are called unsaturated fats. Fats with more than one double bond in the tail are called polyunsaturated fats. 6.4 The Building Blocks of Life Chapter 6
Chemistry in Biology Proteins A compound made of small carbon compounds called amino acids Amino acids are small compounds that are made of carbon, nitrogen, oxygen, hydrogen, and sometimes sulfur. 6.4 The Building Blocks of Life Chapter 6
Chemistry in Biology Amino acids have a central carbon atom. One of the four carbon bonds is with hydrogen. The other three bonds are with an amino group (–NH 2 ), a carboxyl group (–COOH), and a variable group (–R). 6.4 The Building Blocks of Life Chapter 6
Chemistry in Biology The number and the order in which the amino acids are joined define the protein’s primary structure. After an amino acid chain is formed, it folds into a unique three-dimensional shape, which is the protein’s secondary structure, such as a helix or a pleat. 6.4 The Building Blocks of Life Chapter 6
Chemistry in Biology Nucleic acids are complex macromolecules that store and transmit genetic information. Nucleic acids are made of smaller repeating subunits called nucleotides, composed of carbon, nitrogen, oxygen, phosphorus, and hydrogen atoms. 6.4 The Building Blocks of Life Chapter 6
Tusken Raider Mentorship Program Learn to raid, pillage, abduct, and attack like the pros. * *(Students must supply their own gaderffii club and arrange their own bantha transportation)
Chemistry in Biology Chapter Resource Menu Chapter Diagnostic Questions Formative Test Questions Chapter Assessment Questions Standardized Test Practice biologygmh.com Glencoe Biology Transparencies Image Bank Vocabulary Animation Chapter 6 Click on a hyperlink to view the corresponding lesson.
A. electron B. isotope C. neutron D. proton Which of the following particles is negatively charged? Chemistry in Biology Chapter Diagnostic Questions Chapter 6
A. electrons B. neutrons C. protons D. ions Isotopes are created by a change in the number of what particle of an atom? Chemistry in Biology Chapter Diagnostic Questions Chapter 6
A. substrates B. enzymes C. ions D. reactants Identify the proteins that speed up the rate of chemical reactions. Chemistry in Biology Chapter Diagnostic Questions Chapter 6
A. neutrons and electrons B. protons and electrons C. protons and neutrons What particles are in an atom’s nucleus? Chemistry in Biology 6.1 Formative Questions Chapter 6
A. an equal number of protons and neutrons B. an equal number of protons and electrons C. an equal number of neutrons and electrons What causes the overall charge of an atom to be zero? Chemistry in Biology 6.1 Formative Questions Chapter 6
A. a compound B. an element C. an isotope D. a mixture What type of substance is water? Chemistry in Biology 6.1 Formative Questions Chapter 6
A. chemical bonds B. ionic compounds C. radioactive isotopes D. van der Waals forces What provides the energy for all living processes? Chemistry in Biology 6.1 Formative Questions Chapter 6
A. a match burning B. salt dissolving C. water boiling D. gasoline evaporating Which is a chemical reaction? Chemistry in Biology 6.2 Formative Questions Chapter 6
Which chemical reaction is endothermic? Chemistry in Biology A. B. 6.2 Formative Questions Chapter 6
A. It acts as a reactant. B. It reduces the amount of heat produced. C. It increases the amount of product. D. It lowers the activation energy. How does an enzyme increase the rate of a chemical reaction? Chemistry in Biology 6.2 Formative Questions Chapter 6
What occurs at the active site in the enzyme substrate complex? Chemistry in Biology 6.2 Formative Questions Chapter 6
Chemistry in Biology 6.2 Formative Questions Chapter 6 A. An exothermic chemical reaction takes place. B. Chemical bonds are broken and new bonds are formed. C. The enzyme gets used up in the reaction. D. The substrates provide energy for the enzyme.
A. It acts as a catalyst. B. Its pH is neutral. C. It is a polar molecule. D. It is an ionic compound. Why is water able to dissolve a wide variety of solutes? Chemistry in Biology 6.3 Formative Questions Chapter 6
A. covalent bonds B. double bonds C. hydrogen bonds D. ionic bonds What type of bonds attracts water molecules to each other and to other substances? Chemistry in Biology 6.3 Formative Questions Chapter 6
A. Cl – B. OH – C. H + D. Na + Which ion, when released in water, causes a solution to be basic? Chemistry in Biology 6.3 Formative Questions Chapter 6
A. alkali B. antacid C. buffer D. neutralizer What is the name for a substance that keeps the pH in cells within the 6.5 to 7.5 pH range? Chemistry in Biology 6.3 Formative Questions Chapter 6
A. carbon B. nitrogen C. phosphorus D. sodium Which element do almost all biological molecules contain? Chemistry in Biology 6.4 Formative Questions Chapter 6
A. 1 B. 2 C. 4 D. 8 How many covalent bonds can carbon form with other atoms? Chemistry in Biology 6.4 Formative Questions Chapter 6
A. hormone B. nucleic acid C. protein D. steroid What type of biological molecule is an enzyme? Chemistry in Biology 6.4 Formative Questions Chapter 6
A. lipids B. nucleotides C. polypeptides D. sugars What are fats, oils, and waxes composed of? Chemistry in Biology 6.4 Formative Questions Chapter 6
A. amino acids B. fatty acids C. glycerols D. nucleotides What are the monomers that make up proteins? Chemistry in Biology 6.4 Formative Questions Chapter 6
A. carbohydrate B. lipid C. nucleic acid D. protein Which biological molecule transports substances between cells? Chemistry in Biology 6.4 Formative Questions Chapter 6
A. activation energy B. reactants C. products D. enzymes Look at the following figure. Determine what the upward curve represents. Chemistry in Biology Chapter Assessment Questions Chapter 6 ?
A. 2 B. 4 C. 6 D. 8 Look at the energy levels in the atom. What is the maximum number of electrons energy level two can hold? Chemistry in Biology Chapter Assessment Questions Chapter 6
Explain why chemical equations must be balanced. Chemistry in Biology Answer: Chemical reactions require balance of mass. Therefore, the number of atoms of each element on the reactant side must equal the number of atoms of the same element on the product side. Chapter Assessment Questions Chapter 6
A. atoms sharing electrons B. table salt dissolving in water C. ionic compounds forming crystals D. water molecules forming droplets Which is a result of van der Waals forces? Chemistry in Biology Standardized Test Practice Chapter 6
What is true of this chemical reaction? Chemistry in Biology Standardized Test Practice Chapter 6
A. Energy is not needed to start the chemical reaction. Chemistry in Biology Standardized Test Practice Chapter 6 B. Heat and/or light energy are released in this reaction. C. The activation energy is greater than the energy released. D. The energy of the products and the reactants is the same.
A. tomatoes B. bananas Which fruit contains a higher concentration of hydrogen ions? Chemistry in Biology Standardized Test Practice Chapter 6
A. They are energy-storing polymers. B. They are found in the cells of animals. C. They are structural polysaccharides. What do cellulose and chitin have in common? Chemistry in Biology Standardized Test Practice Chapter 6 D. They are composed of repeating sucrose units.
A. gluten B. glycogen C. starch D. sucrolose Which polysaccharide stores energy in muscle and liver tissue? Chemistry in Biology Standardized Test Practice Chapter 6
What is the function of this biological macromolecule? Chemistry in Biology Standardized Test Practice Chapter 6
A. communicate signals between cells B. produce vitamins and hormones C. provide support and protection D. store and transmit genetic information Chemistry in Biology Standardized Test Practice Chapter 6
Which is a characteristic of all lipids? Chemistry in Biology Standardized Test Practice Chapter 6 A. They are saturated triglycerides. B. They do not dissolve in water. C. They are liquid at room temperature. D. They store less energy than carbohydrates.
Chemistry in Biology Glencoe Biology Transparencies Chapter 6