BIOCHEMISTRY: THE BASIC INGREDIENTS OF LIFE

Chapter 3 Biochemistry: The basic ingredients of life Learning Outcomes Differentiate between atoms, elements, and ions. Define acids, bases, and pH, and their roles in the body. Describe molecular bonding. Discuss the biological importance of water. Describe the properties of a solution. Distinguish among the types of biological molecules. Explain metabolism. Explain the role of enzymes in physiology. Explain cellular respiration. Lecture Outline I. Biochemistry A. Atoms, Elements, and Ions 1. Element a. Smallest unit of matter b. Retains chemical properties; cannot be broken into smaller pieces by chemical techniques. c. Abbreviated using first two letters of technical name d. Trace elements: elements the body needs in small amounts 2. Molecule a. Two or more elements joined together b. Form compounds when two or more molecules are joined together. 3. Atoms a. Smallest particles of elements that still maintain the element's characteristics b. Nucleus contains: i.. Protons: positively charged particles ii.. Neutrons: neutral or noncharged particles c.. Electrons: negatively charged particles that circle nucleus 4. Ions a. Atoms that gain or lose electrons b. Polar: charged c. Gain electron, negative charge. d. Lose electron, positive charge. e. Electrolytes: charged ions found within the body that are physiologically important. Examples include sodium, calcium, magnesium, hydrogen phosphate, and bicarbonate. B. Acids and Bases 1. Acid: a chemical substance that can release hydrogen ions 2. Base: a chemical substance that can accept hydrogen ions 3. pH: based on concentration of hydrogen ions 4. Measures relative strength of acids and bases. 5. pH < 7 is acid; pH = 0 is neutral; pH > 7 is basic (alkaline). 6. Strong acids and bases are harmful to living tissue. 7. Acid/base balance is carefully regulated primarily by the renal and respiratory systems. C. Molecular Bonding 1. Elements bound together to form molecules 2. Three types of bonds: a. Ionic bond: One atom gains electrons, the other loses them. Molecule is polar. b. Covalent bond: Atoms share electrons equally. Nonpolar. c. Polar covalent bond: Atoms share electrons unequally. Polar. D. Water 1. Chief liquid in biological systems 2. Polar covalent—unique characteristics a. Molecules classified based on relationship to water i. Hydrophilic: Will mix with water; literally “water loving.” ii. Hydrophobic: Will not mix with water; literally “water fearing.” b. Hydrogen bond i. Weak bond between hydrogen on one molecule and oxygen on another ii. Increased heat capacity; water heats up and cools off more slowly than air. E. Solutions 1. One substance dissolved in another is called a solution. 2. Solute: what’s dissolved 3. Solvent: the dissolver 4. Concentration: amount of solute in solution 5. Some solutions, such as normal saline, act as diluents (fillers, thinners). F. Biological Molecules 1. Molecules found in living systems 2. Contain mainly carbon, hydrogen, and smaller amounts of oxygen, nitrogen, phosphorous; four classes include carbohydrates, lipids, proteins, and nucleic acids. 3. Carbohydrates a. Two hydrogens and one oxygen for each carbon (CH2O) b. Used mainly for energy storage (sugars and starches) c. Hydrophilic d. Classification i. Monosaccharides: simple sugars, 5–6 carbons; example: glucose ii. Disaccharides: two monosaccharides bound together; example: sucrose iii. Polysaccharides: chain of monosaccharides; starches; glycogen stored in the liver for energy 2. Lipids a. Two hydrogens for every carbon, very little oxygen b. Hydrophobic c. Used for energy storage, communication, protection d. Classification i. Fats and oils: glycerol and three fatty acid chains; familiar ii. Waxes: fatty acid chains and alcohol; most hydrophobic substance in body iii. Phospholipid: phosphate “head” hydrophilic; fatty acid “tails” hydrophobic; in cell membrane iv. Steroids: carbon atoms that are arranged in rings; used for communication between cells 3. Proteins a. Long chains of amino acids b. Always recognizable by the nitrogen atoms in the backbone of the molecule; peptide bond ties amino acids together. c. Very versatile in function d. Structure determined by amino acid order e. Denaturation: the process by which proteins lose their structure by application of an external stress or compound; this loss of structural integrity disrupts the ability of the proteins to perform their intended function. 4. Nucleic acids a. RNA and DNA b. Long chains of nucleotides c. Genetic molecules G. Metabolism 1. All the chemical reactions that take place in cells. 1. Anabolism: making large molecules from small ones; dehydration synthesis reactions occurs when water is removed and biological molecules join to form larger molecules. 2. Catabolism: breaking down large molecules into small; hydrolysis reactions occur when water is added to break apart large molecules. H. Enzymes: Making Reactions Happen 1. Most chemical reactions too slow to sustain cells 2. Enzymes speed up (catalyze) reactions. a. Protein molecules b. Not used up in reaction c. Molecules bind to enzyme and are carried through reaction. d. Characteristics i. Specificity: Only certain molecules can be carried by certain enzymes. ii. Competition: Molecules can compete for binding sites. iii. Inhibition: Enzyme can be blocked or prevented from working. iv. Saturation: Binding sites are full and molecules must wait for an empty enzyme before going through the reaction. I. Cellular Respiration and Adenosine Triphosphate (ATP): The Energy Molecule 1. Cellular respiration a. Uses glucose and oxygen. b. Makes carbon dioxide and water as waste. c. Makes lots of adenosine triphosphate (ATP). 2. ATP a. Made of a base, a sugar, and (adenine) and three phosphates b. Remove one phosphate, release energy to use to run metabolism, and becomes ADP (adenosine diphosphate), which can pick up another phosphate to form ATP again. Classroom Activities 1. Assign students to the roles of enzymes and substrates. Have them act out enzyme activity. Demonstrate specificity, competition, inhibition, and saturation. 2. Provide students with descriptions of a number of molecules. Using the characteristics of biological molecules, ask students to classify the molecules. Teaching Strategy 1. Many biological molecules and their characteristics are familiar to students. Use as many familiar examples as possible to illustrate the characteristics of different classes of biological molecules. Factoid 1. Fat has nearly twice as many calories as carbohydrates or proteins. 2. Fat in the human body is characterized as white fat and brown fat. White fat stores extra calories, while brown fat burns calories. Researchers are investigating ways to genetically reprogram white fat cells into brown fat cells, which one day might help in the treatment of such conditions as obesity and diabetes. Ethical Dilemma 1. Fat is needed by the body for many vital functions, such as a properly functioning immune system. However, it gets a very bad rap because of our diet-conscious society and a negative association with the word fat. This can cause some people to engage in unhealthy diets because they do not understand the need for fat intake and the various types of fats. Do you think a campaign should be launched to better explain this? Answers To Test Your Knowledge Test Your Knowledge 3–1 Answers, p. 42 1. atom 2. ions 3. electrolytes 4. solute; solvent 5. acid, decrease 6. diluents 7. 1% Test Your Knowledge 3–2 Answers, p. 45 1. Biological 2. amino acids 3. lipids 4. a. hydrophilic b. hydrophobic c. hydrophobic 5. energy Test Your Knowledge 3–3 Answers, p. 48 1. b 2. a 3. c 4. removed 5. ATP Answers to the Case Study, p. 49 A. Diuretics have side effects, including depletion of the electrolyte potassium. The chief side effect of low potassium is heart palpitations. B. Divya needs a potassium supplement and counseling concerning the dangerous practice of using diuretics to lose weight. C. Diuretics help rid the body of excess water and are therapeutic in a number of conditions, but are not to be used for weight loss, as this is not a true weight loss, and this practice has potentially dangerous side effects. Students who have researched diuretic use may describe hyperkalemia, or excess potassium, if using a potassium-sparing diuretic or hypokalemia (too little potassium) if using a thiazide diuretic. Some other side effects include dizziness, headache, muscle cramps, hyponatremia (low blood sodium), increased cholesterol, and rash. Answers to Review Questions, pP. 49–50 Multiple Choice 1. d, 2. b, 3. c, 4. c, 5. d Fill in the Blank 1. ions 2. polar covalent 3. electrolytes 4. water 5. metabolism 6. ATP Short Answer 1. Element: smallest unit that retains chemical characteristics; Atoms: smallest unit of element; Molecule: two or more elements bound together; Ion: atoms that gain or lose electrons 2. Ionic bond: One atom loses electrons while other gains them; polar. Covalent bond: Atoms share electrons equally; nonpolar. Polar covalent: Atoms share electrons unequally; polar. 3. Carbohydrates: Have two hydrogens and one oxygen for each carbon; used for energy storage; hydrophilic. Lipids: two or three hydrogens for every carbon, very little oxygen; used for energy storage and protection; hydrophobic. Proteins: long chain of amino acids, have nitrogen in molecule, very versatile. Nucleic acids: chains of nucleotides, genetic molecules. 4. Water is a polar covalent molecule with hydrogen bonding between molecules. It carries a charge. Its heat capacity is very high, causing water to heat up and cool down much more slowly than air. Polar molecules can mix with water, whereas nonpolar molecules cannot. Water is important to biological systems because it is the chief solvent in cells and tissues. 5. Enzymes are protein molecules that speed up biological reactions. The molecules bind to a site on the enzyme and are carried through the reaction. The enzyme is not used up during the reaction. Enzymes are very specific, speeding up only certain reactions. They can also be saturated (filled up), they can be inhibited (blocked), and molecules can compete for individual enzymes. 6. For cells to carry out metabolism, they must have energy in the form of ATP, which is made via a complex series of reactions called cellular respiration. During cellular respiration, glucose combines with oxygen and is transformed in the mitochondria into adenosine triphosphate (ATP). The phosphate groups in ATP are held together by high-energy bonds. When a bond is broken, a high level of energy is released and can be used by the cells. When a bond is used, ATP becomes ADP (adenosine diphosphate), which has only two phosphate groups. The ADP is now able to pick up another phosphate and form a high-energy bond so energy is stored and the process can begin again. Name __________________ Chapter 3—Worksheet Multiple Choice 1) Which of the following is a characteristic of enzymes? A) Saturation B) Lipid C) Used up during reaction D) Nonspecific 2) Proteins are made of long chains of: A) nucleic acids. B) amino acids. C) lewis acids. D) citric acids. 3) This type of bond is nonpolar: A) Hydrogen B) Polar-covalent C) Ionic D) Covalent 4) _____ surround the atomic nucleus. A) Electrons B) Protons C) Neutrons D) Plutons 5) The point of cellular respiration is to make: A) water. B) glucose. C) ATP. D) metabolism. 6) Molecules that have one oxygen for each carbon are called: A) proteins. B) carbohydrates. C) lipids. D) nucleic acids. 7) IV drugs are often mixed with __________ such as sterile water if they will be delivered to a patient over a long period of time. A) solutes B) lipids C) diluents D) bases Worksheet—p. 1 of 2 Fill in the Blank 8) _____ occurs when a protein loses its structure and cannot perform its intended functions. 9) The measure of the acidity of solutions is _____. 10) Hydrophobic molecules will not _____ with water. 11) Glycogen, an energy storage molecule, is this type of molecule: _____. (Be specific.) 12) _____ molecules are important in the function of cell membranes. 13) _____ reactions are the chief reactions of catabolism. 14) The prevention of a substrate from binding to an enzyme binding site is called _____. 15) This class of biological molecule is always hydrophobic: _____ Matching 16. _____ Element 17. _____ Ion 18. _____ Monosaccharide 19. _____ Wax 20. _____ Electrolyte 21. _____ Trace element 22. _____ Molecule 23. _____ Polysaccharide 24. _____ Solute 25. _____ Solution A. Fatty acid with alcohol B. Biologically important ion C. What is dissolved in solution D. Smallest unit that retains chemical characteristics E. Solute dissolved in solvent F. Sugar with 5–6 carbons G. Biologically important element H. Charged atom or molecule I. Many sugars linked together J. Two or more elements bound together Worksheet—p. 2 of 2 Answer Key Chapter 3—Worksheet 1) A 2) B 3) D 4) A 5) C 6) B 7) C 8) Denaturation 9) pH 10) mix, dissolve 11) polysaccharide 12) Phospholipid 13) Hydrolysis 14) inhibition 15) lipids 16) D 17) H 18) F 19) A 20) B 21) G 22) J 23) I 24) C 25) E 12 StudyForce.com 12 StudyForce.com 12 StudyForce.com