Chapter 2 The Chemical Basis of Life

2. Chapter 2The Chemical Basis of Life (BIOCHEMISTRY) THE BULK OF PHYSIOLOGY INVOLVES CHEMICAL REACTIONS, BUILDING UP or BREAKING DOWN MOLECULES UTILIZING ENERGY or PRODUCING ENERGY

3. Basic Chemistry: Key terms and concepts ATOMS MOLECULES Elements and compounds Elements in the human body (table 2-1) PROTONS ELECTRONS NEUTRONS Electron shells / energy levels , octet rule, attractions CHEMICAL BONDS: IONIC, COVALENT, weak bonds – hydrogen CHEMICAL REACTIONS: SYNTHESIS, DECOMPOSITION, EXCHANGE: REVERSIBLE

4. MORE KEY TERMS: METABOLISM : CATABOLISM vs. ANABOLISM ENZYMES INORGANIC COMPOUNDS , such as H2O, O2 ELECTROLYTES ; IONS: ANIONS, CATIONS ph ACIDS, BASES, BUFFERS, SALTS ORGANIC COMPOUNDS: CARBOHYDRATES LIPIDS PROTEINS (& Combos) NUCLEIC ACIDS: DNA, RNA, NUCLEOTIDES ADENOSINE TRIPHOSPHATE (ATP)

5. BASIC CHEMISTRY Element — simple form of matter; a substance that cannot be broken down into two or more different substances (PURE) ~118 of them (ref. periodic table) ex . Hydrogen, oxygen, helium, carbon, gold, silver, copper, sodium, molybdenum, nitrogen, calcium, phosphorus

7. Basic Chemistry • There are 26 elements in the human body • THERE ARE 11 “MAJOR ELEMENTS,” 4 OF WHICH ( OXYGEN, CARBON, HYDROGEN, & NITROGEN ) MAKE UP 96% OF THE HUMAN BODY (water, H2O is 60-80% of the body) (the others are: sodium, potassium, chlorine, calcium, phosphorus , sulfur, magnesium) • & There are 15 “trace elements” that make up less than 2% of body weight

8. Table 2-1:Elements in the human body 11 MAJOR elements: Oxygen Carbon Hydrogen Nitrogen Calcium Phosphorus Sodium Chlorine Potassium Sulfur Magnesium

9. Table 2-1‘trace’elements, but significant roles Iron blood (Hemoglobin) Copper many enzymes Iodine thyroid hormone several obscure others

10. **Basic unit of the elements: the ATOM **

11. BASIC CHEMISTRY H O O H H H O O H O O H H H Compound—atoms of two or more elements joined to form chemical combinations -- made up of MOLECULES atoms MOLECULES

12. Basic Chemistry • ATOMIC STRUCTURE— • ATOMS contain subatomic particles; the most important are the following: • PROTONS (+ or p)—positively charged particles found in the nucleus • NEUTRONS (n)— neutral subatomic particles found in the nucleus • ELECTRONS (– or e)—negatively charged subatomic particles found in the electron cloud surrounding, moving about the nucleus

13. Basic Chemistry • Energy levels (cont.) • a model resembling planets revolving around the sun, useful in visualizing the structure of atoms • Exhibits electrons in concentric circles showing relative distances of the electrons from the nucleus • Each ring or shell represents a specific energy level and can hold only a certain number of electrons

14. Basic Chemistry • Energy levels (Figures 2-3 and 2-4) • The total number of electrons in an atom equals the number of protons in the nucleus (in a stable atom) • Thus, it is ‘neutral’ – has no electrical charge • ie.: Carbon: 6 protons, 6 neutrons, 6 electrons • The electrons form a “cloud” around the nucleus

15. Electron energy levels, cont. The NUMBER and arrangement of Electrons determine whether the atom is chemically active. In Chemical reactions, it is the electrons in the outer levels which participate in forming CHEMICAL BONDS If an atom has 8 electrons in the outermost level, it is chemically ‘inert’, or inactive, and ‘unavailable’ . (octet rule)

16. Basic Chemistry • Energy levels (cont.) • Octet rule — atoms with fewer (or more) than eight electrons in the outer energy level will attempt to lose, gain, or share electrons with other atoms to achieve stability. {just like lonely MALE or FEMALE COLLEGE STUDENTS !!!! }

17. Basic Chemistry • THESE Attractions between atoms result in chemical bonds– (key concept in Chemistry) • CHEMICAL REACTION — interaction between two or more atoms that occurs as a result of activity between electrons in their outermost energy levels • The result: Formation of: MOLECULES and COMPOUNDS

18. BASIC CHEMISTRY H O O H H H O O O H O H H H Compound—atoms of two or more elements joined to form chemical combinations -- made up of MOLECULES atoms Slide 18

19. BASIC CHEMISTRY MOLECULES , (COMPOUNDS) can be SIMPLE: such as; O2 H2O CO2 COMPLEX C40H62N10O12 & in between C6H12O6

21. Basic Chemistry • Chemical bonds — unite atoms into molecules two major types of chemical bonds: • IONIC BOND: formed by transfer of electrons; strong electrostatic force that binds positively and negatively charged ions together • COVALENT BOND:formed by sharing of electron pairs between atoms

22. Ionic bond: donated electron

23. Hydrogen molecule H2Hh2 Covalent bonds, shared electrons Carbon dioxide CO2

24. Other types of bonds H + H H o- + + o O- H H + + H + + Etc etc • HYDROGEN BOND • Much weaker than ionic or covalent bonds • Results from unequally shared electrons, and thus unequal charge distribution on molecules, it makes molecules ‘polar’ • water is a good example: ( also DNA - has many H bonds)

25. Chemical reactions • CHEMICAL REACTIONS Involve the formation or breaking of chemical bonds • There are three basic types of chemical reactions involved in physiology: • SYNTHESIS REACTION— combining of two or more substances to form a more complex substance; formation of new chemical bonds: A + B → AB • DECOMPOSITION REACTION— breaking down of a substance into two or more simpler substances; breaking of chemical bonds: AB → A + B • EXCHANGE REACTION— decomposition of two substances and, in exchange, synthesis of two new compounds from them: AB + CD → AD + CB • (so it’s a combo. of the other two Rxn)

26. REVERSIBLE REACTIONS— occur in both directions • Most of the metabolic, physiologic chemical reactions of the body can and do take place in either direction, • So, in essence, a synthesis reaction, when reversed, becomes a decomposition reaction

27. Metabolism Metabolism — the sum total of all of the chemical reactions that occur in body cells Catabolism = decomposition Anabolism = synthesis

28. CATABOLISM • Chemical reactions that break down complex compounds into simpler ones and release energy; • HYDROLYSIS is the most common catabolic reaction,,,,,,,, WATER is added to a substance, resulting in its breakdown into smaller compounds • Ultimately, the end products of catabolism are carbon dioxide, water, and other waste products • More than half the energy released is transferred to ATP, which is then used to do cellular work

29. Metabolism • Anabolism • Chemical reactions that join simple molecules together to form more complex molecules • The Chemical reaction most commonly responsible for anabolism is DEHYDRATION SYNTHESIS

32. MORE KEY TERMS METABOLISM : CATABOLISM ANABOLISM INORGANIC COMPOUNDS , such as H2O, O2 ELECTROLYTES IONS, ANIONS, CATIONS pH: ACIDS, BASES, BUFFERS, SALTS ORGANIC COMPOUNDS table 2-4 CARBOHYDRATES LIPIDS PROTEINS (& Combos) ENZYMES NUCLEIC ACIDS DNA RNA NUCLEOTIDES ADENOSINE TRIPHOSPHATE (ATP)

33. Organic and Inorganic Compounds • ORGANIC MOLECULES • Have at least one carbon atom and at least one C–C or C–H bond in each molecule (they are complex molecules) Can have a bunch of atoms • Often have functional groups attached to the carbon- containing core of the molecule (ex: of functional groups): • hydroxyl carbonyl carboxl amino phosphate -OH -C=O -COOH -C=NH2 -O-P=O(OH)2 ATP: adenisine triphosphate

34. INORGANIC COMPOUNDS such as :H2O O2CO2electro-lytes: Na+ K+ Cl- Ca++ othersin contrast to organic molecules:inorganic Do not generally have carbon atoms if so, there are NO C–C or C–H bond,(they are much more simple molecules)60%-80% of your body is water

35. INORGANIC COMPOUNDS WaterThe body’s most abundant and important compound: where is water found in the body?: Intracellular fluid (inside the body) Extracellular fluid (outside the body), to include blood (intravascular) HOW IS WATER UTILIZED? a Solvent, ( thus a carrier) , for important substances involved in a vital way in most chemical reactions

37. WATER • Important Properties of water (Table 2-2) • Polarity — allows water to act as an effective solvent; ionizes substances in solution (Figure 2-8) • Ionized: to go from a solution to being dissolved • The solvent allows transportation of essential materials throughout the body (Figure 2-12) • High specific heat — water can lose and gain large amounts of heat with little change in its own temperature; ENABLES THE BODY TO MAINTAIN A RELATIVELY CONSTANT TEMPERATURE • High heat of vaporization—water requires absorption of significant amounts of heat to change from a liquid to a gas, ALLOWING THE BODY TO DISSIPATE EXCESS HEAT

38. Inorganic Compounds • Oxygen and carbon dioxide—closely related to cellular metabolism: Oxygen — • REQUIRED to complete decomposition reactions necessary for the release of energy in the body Carbon dioxide — • produced as a waste product of decompensationreactions • also helps maintain the appropriate ACID-BASE balance in the body

39. Inorganic Compounds • Electrolytes • Large group of inorganic compounds, which includes acids, bases, and salts • Substances that dissociate in solution to form IONS (these are NOT ‘Saturn’ cars, LOL) • Positively charged ions are cations; • negatively charged ions are anions • The major electrolytes are: • Sodium (NA+) Potassium (K+) Chloride(CL-) Carbon Dioxide (CO2) Calcium (Ca++) many others

40. Inorganic Compounds • Electrolytes (cont.) • Acids and bases—common and important chemical substances that are chemical opposites • ACIDS • Any substance that RELEASES A HYDROGEN ION (H+) when in solution; • Described as “proton donors” • Level of “acidity” depends on the number of hydrogen ions a particular acid will release (low pH) pH: 6.9 and below is acidic impt. ex.: HCL hydrochloric acid in the stomach lactic acid builds up in tired muscles

41. BASES • Electrolytes that dissociate to YIELD HYDROXIDE IONS (OH–) or other electrolytes that combine with hydrogen ions (H+) • Described as “proton acceptors” • pH: 8.0 and above are basic (high pH) examples: NaOH, NaHCO3 , CaHCO3, Ammonia

42. pH scale—measuring acidity and alkalinity • pH indicates the degree of acidity or alkalinity of a solution pH of 7 indicates NEUTRALITY (equal amts of H+ and OH–); a pH of less than 7 indicates ACIDITY; • a pH of more than 7 indicates ALKALINITY ***** ‘normal’ pH of the blood (body) is 7.4 ****** ****** this is important !!!!!!!

44. Inorganic Compounds • Buffers • Maintain the constancy of the pH • Minimize changes in the concentrations of H+ and OH– ions • Act as a “reservoir” for hydrogen ions • most important buffer for maintaining acid-base balance in the blood is the • carbonic-acid-bicarbonate buffer. • H+ + -HCO3 >< H2CO3>< H2O + CO2 • Gives up hydrogen ions

45. Inorganic Compounds • Salts (Table 2-3) • Compounds that result from chemical interaction of an acid and a base • Reaction between an acid and a base to form a salt and water is called a neutralization reaction • NaOH + HCL >> NaCl + H2O • base acid salt water

46. Organic Molecules (Figure 2-14; Table 2-4) “Organic” describes compounds that contain C–C or C–H bonds. (complex) in the Human Body, the key ORGANIC COMPOUNDS are: CARBOHYDRATES LIPIDS, INCLUDING STEROIDS PROTEINS NUCLEOTIDES, NUCLEIC ACIDS, ATP

50. 2 East Texas farmers: • #1: MR DUCKS • #2: MR KNOT • #1: OSAR, • CM WANGS • #2 : LIB, • MR DUCKS