Chemistry and biological molecules

1. Chemistry and biological molecules

2. Matter is anything that occupies space and has mass. Energy is the capacity to do work. Potential (stored) energy Kinetic energy (energy of motion)

3. Elements are substances which cannot be split into simpler substances by ordinary chemical reactions. Each element has a one or two letter chemical symbol.

4. O Oxygen 65 % of total body weight C Carbon 18.6 H Hydrogen 9.7 N Nitrogen 3.2 Ca Calcium 1.8 P Phosphorus 1.0 K Potassium 0.4 Na Sodium (Natrium) 0.2 Cl Chlorine 0.2 Mg Magnesium 0.06 S Sulfur 0.04 Fe Iron (Ferrum) 0.007 I Iodine 0.0002

5. O, C, H, N = 96 % of body weight Add Ca and P = 98.5 % of body weight Add K, S, Cl, Na and Mg = 99.9.% of body weight “Bulk Elements”

7. Atoms are the smallest unit of an element that still has the chemical properties of that element. Atoms: Have a central nucleus Protons (+) Neutrons (0) Orbitals on the outside that hold Electrons (-)

11. The number of electrons in the outermost shell determines how each atom interacts with other atoms. Atomic number = the number of protons in the atom. Atomic weight (or Mass number) = the total number of protons and neutrons Expressed in daltons or atomic mass units

12. Isotopes are atoms of an element that all have the same number of protons, but have different numbers of neutrons. Radioisotopes – radioactive decay The time it takes for half of a radioactive substance to decay is called its half-life.

14. When two or more atoms combine in a chemical reaction, a molecule is formed. When a molecule contains two or more atoms of different elements, it is called a compound. CO2 H2O NaCl C12H22O11

15. Atoms are held together by forces of attraction called chemical bonds, which are forms of potential energy. Ionic bonds Covalent bonds Hydrogen bonds

16. In an ionic bond electrons are transferred from one atom to another. Opposing charges hold the atoms together. An ion is a charged particle (atom or molecule). Na+ Ca++ positive charge - cations Cl- HCO3- negative charge – anions Substances that breaks into positively and negatively charged ions in solution are called electrolytes.

18. An ion or molecule that that contains unpaired electrons in its outermost energy level is called a free radical. Nitric Oxide is a free radical neurotransmitterblood clotting and vessel dilationdefense against pathogen Cumulative damage = aging process

19. Covalent bonds are formed when atoms share electrons. These are the strongest bonds. C - C Double covalent bonds C=C Triple covalent bonds N≡N

22. When one end of molecule has a positive charge (δ+) and the other has a negative charge(δ-), the molecule is polar. (polar covalent bonds) When molecules have a more uniform distribution of charges they are called nonpolar molecules. (nonpolar covalent bonds)

23. Polar molecules are hydrophilic . “water loving” Nonpolar molecules are hydrophobic. “water fearing” Surface tension slows rate of evaporation lung function tear film

25. Hydrogen bonds are weak but important bonds. They do not bind atoms into molecules, but are important in giving large molecules their shape.Involve interaction between δ+ of a hydrogen and δ- of oxygen, nitrogen or fluorine

26. Chemical reactions involve making and breaking bonds. Making bonds requires the input of energy. Energy is stored in molecules in the chemical bonds. Breaking bonds usually releases energy.

27. Synthesis reactions - Anabolism A + B → AB Reactants Products Decomposition reactions – catabolism AB → A + B

28. Exchange reactions involve the replacement of one atom or atoms by another atom or atoms. AB + CD → AD + BC

29. In Reversible reactions end products can revert to the original combining molecules. AB ↔ A + B CO2 + H2O ↔H2CO3↔ H+ + HCO3- carbonic bicarbonate acid ion

30. Catalysts are molecules that influence the rates of chemical reactions, but are not consumed (used up) in the reaction. Enzymes are biological catalysts (proteins). -ase Activation energy Exergonic or exothermic Endogonic or endothermic

31. Inorganic CompoundsCO2, O2, H2O and acids, bases and salts Inorganic acids, bases and salts dissociate into ions in water. Acids - one or more hydrogen ions (H+) and one or more anions. Bases - hydroxide ion (OH-) and one or more cations.

32. A salt ionizes into anions and cations, neither H+ nor OH-

33. pH The pH is the negative log of the hydrogen ion concentration. The more hydrogen ion a solution has, the lower its pH is.

36. Why is pH critical to body functioning?

37. Water Water is the most abundant substance in the body. It is an excellent solvent. Water participates in chemical reactions: dehydration synthesis - combines atoms with the removal of water hydrolysis – breaks apart molecules with the addition of water.

39. Water has a high heat capacity – good for cooling. Good for lubrication (pleura, etc.) Good suspending medium - blood Inorganic substances usually lack carbon and are small molecules; many contain ionic bonds and are electrolytes.

40. Inorganic ions are important to body functions Na+, K+, Ca++, HCO3-

41. Organic molecules Organic compounds always contain carbon. Other common elements are hydrogen, oxygen and nitrogen. Carbon compounds are held together by covalent bonds, tend to decompose easily, and are a good source of energy.

42. Macromolecules – large organic molecules Formed by linking smaller repeating units called monomers together. (subunits) Many monomers linked together make a large molecule called a polymer.

43. Classes of organic molecules • Carbohydrates (sugars) • Lipids • Proteins • Nucleic Acids

44. Carbohydrates • Supply energy and build some cell structures • Include sugars, starches, glycogen and cellulose • Always Cx(H2O)y • can have same formula (glucose and fructose) but differ in shape (isomers) • Monosaccharides are the monomers

45. Simple sugars

46. 3-7 carbons • Names end in –ose • Mono and disaccharides dissolve in water and are rapidly distributed • Polysaccharides formed by dehydration synthesis • Chains can be straight or highly branched • Glycogen in liver and muscle • Polysaccharides do not dissolve in water and are not “sweet”

48. Lipids • Contain C, H, O • C:H nearly 1:2 • Tend to be hydrophobic (nonpolar) • Tend to be insoluble in water (blood) • Diverse group : fats, oils, waxes • Fatty acids, triglycerides, phospholipids, glycolipids, steroids and eicosanoids

49. Lipids • Concentrated chemical energy • Good storage form • Cell membranes • Protect • Insulate

50. Fatty acids • One end has a carboxyl group – COOH • Hydrocarbon tail • The longer the tail the lower the solubility • Fatty acids bind to glycerol to form neutral fats or triglycerides