1. C HAPTER 2 T HE C HEMISTRY OF L IFE

2. Section 2-1 Atom: Smallest unit of matter; can’t be broken down by chemical means. Atom has 3 particles: electrons (e-), protons (p+), neutrons (n). e- orbit nucleus in different energy levels p+ and n are in nucleus of the atom

3. Section 2-1 Element: Pure substance (sub) made of 1 kind of atom Elements differ in # of p+ their atoms contain # of n in atom is often but not always = to # of p+ in atom Oxygen atom

4. Section 2-1 Compound: sub made by joining atoms of 2 or more diff elements Atoms can join w/other atoms to form stable sub Force that joins atoms is called a chemical bond

5. Section 2-1 Covalent Bonds: Form when 2 or more atoms share e- Molecule: Group of atoms held together by covalent bonds.

6. Section 2-1 Hydrogen Bonds: In water, shared e- are attracted more strongly by O nucleus than by H nuclei Molecules w/unequal distribution of charge, such as water, are polar molecules Attraction between 2 water molecules is ex of hydrogen bond —weak chem attraction between polar molecules

7. Section 2-1 Ionic Bonds: Atom/molecule that gain/lose 1 or more e- is an ion Ions have electrical charge because they contain unequal # of e-/p+. Ions of opposite charge interact to form ionic bond

8. Section 2-2 Importance of Water to LT: Many organisms release excess heat through water evaporation This ability to control temp helps cells to maintain constant internal temp when external temp changes Water helps cells maintain homeostasis!

9. Section 2-2 Cohesion: Attraction between sub of the same kind Because of cohesion, water and other liquids form thin films/drops Molecules at surface of water are linked together by H bonds like a crowd of people linked by holding hands. This attraction between water molecules causes surface tension Surface tension

10. Section 2-2 Adhesion: Attraction between different substances Adhesion causes capillary action, in which water molecules move upward through narrow tube, such as stem of a plant

11. Section 2-2 Solution: Mixture of 1 or more substances evenly distributed in another substance Important substances in the body are dissolved in blood/other aqueous fluids Because these substances dissolve in water, they easily move w/in and between cells

12. Section 2-2 Polarity: Polarity of water enables many substances to dissolve in water When sodium chloride, NaCl, is dissolved in water, Na + and Cl – become surrounded by water molecules, H 2 O

13. Section 2-2 Nonpolar molecules: Nonpolar molecules don’t dissolve in water Inability of nonpolar molecules to dissolve in polar molecules is important to LT Shape/function of cell membrane depends on interaction of polar water w/ nonpolar membrane molecules Outside of cell Inside of cell

14. Section 2-2 Acids/Bases: Compds forming H+ when dissolved in water are acids Compds reduce[H+] in a sol’n are bases Many bases form hydroxide ions (OH-) when dissolved in water When acid is added to water, [H+] in sol’n is ↑ above that of pure water pH scale (0-14) measures [H+] Acids Bases

15. Section 2-3 Carbohydrates: Organic compounds made of C,H,O atoms in proportion of 1:2:1 Key source of energy; found in most foods— fruits, vegetables, grains

16. Section 2-3 Types of Carbohydrates: Building blocks of carbohydrates are single sugars, monosaccharides, glucose, C 6 H 12 O 6, and fructose Single sugars such as glucose are major source of energy in cell

17. Section 2-3 Disaccharides: Double sugar formed by 2 monosaccharides Sucrose, table sugar, consists of glucose and fructose.

18. Section 2-3 Polysaccharides: Starch are chains of 3 or more monosaccharides

19. Section 2-3 Lipids: Nonpolar molecules not soluble in water; fats, phospholipids, steroids, waxes Fats are lipids that store energy Typical fat has 3 fatty acids bonded to a glycerol molecule

20. Section 2-3 Saturated/Unsaturated Fats: Saturated fatty acid, all C atoms are bonded to 2 H atoms (except end C is bonded to 3 H atoms) Unsaturated fatty acid, some C atoms are linked by “double” covalent bond, each w/ only 1 H atom, producing kinks in molecule

21. Section 2-3 Proteins: Molecule formed by amino acids (aa) the building blocks of proteins 20 diff aa can form proteins

22. Section 2-3 Nucleic Acids: (DNA, RNA, ATP) Long chain of nucleotides w/ 3 parts: sugar, base, phosphate group DNA, deoxyribonucleic acid, 2 strands of nucleotides that spiral around each other RNA, ribonucleic acid, single strand

23. Section 2-3 ATP: Adenosine triphosphate, single nucleotide w/energy-storing phosphate gr When food molecules are broken down inside cells, some energy is stored as ATP ATP

24. Section 2-4 Energy: Ability to move/change matter Energy’s in many forms—light, heat, chemical, mechanical, electrical—can be converted from 1 form to another Energy can be stored/released by chem rxn

25. Section 2-4 Energy in Chemical Reactions Energy is absorbed/released when chemical bonds are broken and new ones formed Metabolism is used to describe all the chem rxn that occur w/in an organism Reactant = start with Product = end with

26. Section 2-4 Activation Energy (AE): Energy needed to start chemical rxn AE is a chem “push” that starts chem rxn Even in chem rxn that releases energy, AE must be supplied before rxn can occur

27. Section 2-4 Enzymes: Sub that speed up chemical rxn = catalyst and can lower AE of the rxn Enzymes are proteins that act on a specific substrate by attaching to the active sites of the substrate during a chemical rxn

28. Section 2-4 Enzymes: Example: amylase assists in the breakdown of starch to glucose (hydrolysis) Example: catalase assists in the breakdown of hydrogen peroxide to water and oxygen gas Enzymes in your body probably work best at 98° F or 37° C.

29. Section 2-4 Factors in Enzyme Activity: Factor that ∆ shape of enzyme can affect enzyme’s activity Temp/pH/shape of enzyme can alter enzymes effectiveness Enzymes that are active at any 1 time in a cell determine what happens in that cell