The Chemical Level of Organization

1. The Chemical Level of Organization Chapter 2

2. Atoms and Molecules • Atoms are the smallest units of matter, they consist of protons, neutrons, and electrons

3. Structure of an Atom • An element consists entirely of atoms with the same number of protons. • Within an atom, an elecron cloud surround the nucleus.

5. The atomic mass of an atom is equal to the total number of protons and neutron in its nucleus. • Isotopes are atoms of the same element whose nuclei contain different number of neutrons. • The atomic weight of an element takes into account the abundance of its various isotopes.

6. Electrons occupy a series of electron shells around the nucleus. • The number of electrons in the outer shell determine an atom’s chemical properties.

8. Chemical bonds and chemical compounds • An ionic bond results from the attraction between ions: atoms that have gained or lost electrons. • Cations are positively charged • Anions are negatively charged.

10. Atoms can combine to form a molecule • Combinations of atoms of different elements form a compound • Some atoms share electrons to form a molecule held together by covalent bonds.

11. Sharing one pair of electron creates a single covalent bond • Sharing two pairs forms a double covalent bond • Unequal sharing of electrons creates a polar covalent bond.

13. A hydrogen bond is the attraction between a hydrogen atom with slight positive charge and a negatively charged atom in another molecule or within the same molecule • Hydrogen bond can affect the shaes and properties of molecules

15. Chemical Notation • Chemical notation allows us to describe reactions between reactant tha generate one or more products.

16. Chemical Reactions • Metabolisms refers to all the chemical reaction in the body. Our cells capture, store and use energy to maintain homeostasis and support essential functions.

17. Basic energy concepts • Work involves movement of an object or a change in its physical structure. • Energy is the capacity to perform work. • There are two major types of energy: knetic and potential.

18. Kinetic energy is the energy of motion. • Potential energy is stored energy that results from the position or structre of an object. • Conversions from potential to kinetic energy are not 100% efficient. • Every energy exchange produces heat.

19. Types of Reactions • A chemical reaction may be classified as • Decomposition • Synthesis • Exchange

20. Exergonic reaction release heat • Endergonic reactions absorb heat • Cells gain energy to power their functions by catabolism: the breakdown of complex molecules • Much of this energy supports anabolism, the synthesis of new organic molecules

21. Reversible Reactions • Reversible reactions consist of simultaneous synthesis and decomposition reactions. • At equilibrium the rates of these two opposing reactions are in balance.

22. Acids and Bases • A acid releases hydrogen ions • A base removes hydrogen ions from a solution

23. pH • The pH of a solution indicates the concentration of hydrogen ions it contains. • Solutions can be classified as neutral (pH of 7)acidic (pH < 7) or basic (alkaline) (pH > 7) on the basis of pH

25. Buffers maintain pH within normal limits (7.35-7.45 in most body fluids) by releasing or absorbing hydrogen ions.

26. Inorganic Compounds • Nutrients and metabolites can be broadly classified as organic or inorganic compounds • Living cells in the body generate carbon dioxide and consume oxygen.

27. Water and it Properties • Water is the most important inorganic component of the body • Water is an excellent solvent, has a high heat capacity, and participates in the metabolic reactions of the body. • Many inorganic compounds will undergo ionization, or dissociation in water to form ions.

29. Inorganic Acids and Bases • Inorganic acids found in the body include hydrochloric acid carbonic acid, sulfuric acid and phosphoric acid. • Sodium hydroxide is an inorganic base that may form within the body.

30. Salts • A salt is an ionic compound whose cation is not H+ and whose anion is not OH- • Salts are electrolytes, compounds that dissociate in water and conduct an electrical current.

31. Organic Compounds • Organic compounds contain carbon and hydrogen, and usually oxygen as well. • Large and complex organic molecules include carbohydrates, lipids proteins and nucleic acids.

32. Carbohydrates • Carbohydrates are most important as an energy source for metabolic process. • The three major types are monosaccharides (simple sugars), dissacharides and polysaccharides.

33. A. the straight -chain formula for glucose • B. The ring form that is most common in nature. • An abbreviated diagram fo the ring form.

34. Lipids • Lipids are water-insoluble molecules that include fats, oils, and waxes. • There are four important classes of lipids: fatty acids, fats, steroids, and phospholipids.

35. Triglycerides (fats) consists of three fatty acid molecules attached to a molecule of glycerol • Cholesterol is a precursor of steroid hormones and is a component of cell membranes

37. Phospholipids are the most abundant components of cell membranes.

38. Proteins • Proteins perform a great variety of function in the body. • Important types of protein include structural proteins, contractile proteins, transport proteins, enzymes, hormones and antibodies.

39. Proteins are chains of amino acids linked by peptide bonds. • The sequence of amino acids and the interactions of their R groups influence the final shape of the protein molecules.

41. The shape of the protein determines its function. • Each protein works best at an optimal combination of temperature and pH.

42. Activation energy is the amount of energy required to start a reaction. Proteins called enzymes control many chemical reaction within our bodies. Enzymes are catalysts--substances that accelerate chemical reaction without themselves being permanently changed.

44. The reactants in an enzymatic reaction, called substrates, interact to form a product by bonding to the enzyme at the active site.

46. Nucleic Acids • Nucleic acids store and process information at the molecular level. • There are two kinds of nucleic acids: DNA and RNA • Nucleic acids are chains of nucleotides. • Each nucleotide contains a sugar, a phosphate group and a nitrogen base.

47. The sugar is always ribose or deoxyribose. • The nitrogenous bases found in DNA are adenine, guanine, cytosine, and thymine. In RNA uracil replaces thymine.

49. High-Energy Compounds • Cells store energy in high-energy compounds. • The most important high-energy compound is ATP • When energy is available, cells make ATP by adding a phosphate group to ADP • When energy is needed ATP is broken down to ADP and phosphate.