2 Unit 2 Chapter 2

2 Unit 2 Fundamental unit in chemistry Cannot be broken down by chemical means 112 elements total Use 1-2 letter symbols for each e.g. C= carbon, Na = sodium, Cl = chorine. 26 normally present in your body 4 major ones & 8 others significant (see table 2.1)

2 Unit 2 Lowest unit of an element Nucleus-protons (+), neutrons (0) Surrounded by Electrons (-) Total charge is neutral- Protons # = electron # Proton number=atomic number- defines element

2 Unit 2 Atoms interact in characteristic ways Describing this is chemistry When two or more atoms are held together with chemical bonds the result is a molecule. Described by the molecular formula

2 Unit 2 Example: O 2 = oxygen the gas molecule has 2 atoms of oxygen bound together H 2 O = water Molecule has 2 atoms of H (hydrogen) and 1 atom of O (oxygen) Subscript = # of atoms of element Connected letters & numbers = molecule

Figure 2.3

2 Unit 2 attraction between atoms to form attachments = molecules Electrons grouped into shells preferred number in outer shell leads to chemical activity Can be covalent, ionic, polar covalent and Hydrogen bonds

2 Unit 2 Can donate or accept electrons from another atom -> Ions = atoms with a charge Opposite charges attract => bonding Ionic bonding

Figure 2.4

2 Unit 2 Can share electrons in outer shell - > covalent bonds e.g. water, many organic compounds unequal sharing -> polar bond some partial charges on the molecule

2 Unit 2 Putting atoms together A + B => AB Eg. 2H 2 + O 2 => 2 H 2 O Synthesis in the body = Anabolism

2 Unit 2 Splitting Molecules apart AB => A + B Eg. CH 4 => C + 2H 2 Decomposition in the body = Catabolism

2 Unit 2 Exchange reactions both decomposition & synthesis E. g. AB + CD => AD + BC Reversible reactions Go both directions E. g. AB A + B

2 Unit 2 Good solvent for some molecules Dissolve = Hydrophilic molecules Don’t dissolve = Hydrophobic molecules Participates in chemical reactions Absorbs & releases heat slowly Needs large amount of heat to evaporate

2 Unit 2 Acid dissolves => H + (1 or more) Base dissolves => OH - ( 1 or more) Acid plus base react => salt E.g. HCL + KOH => KCL + H 2 O acid base salt

2 Unit 2 The concentration of H + or OH - expressed on the pH scale 0-14 At pH = 7.0: H + conc. = OH - conc. Less than 7.0 = more H + (acid) The smaller the number, the more H + More than 7.0 = more OH - (alkaline) The larger the number, the more OH -

2 Unit 2 Carbohydrates Lipids Proteins Nucleic acids

2 Unit 2 Simple sugars = Monosaccharide Major one in body = glucose Disaccharides= 2- simple sugars bonded Formed by dehydration synthesis E.g. glucose + fructose => sucrose glucose + galactose => lactose Glucose + glucose => maltose

2 Unit 2 Many sugars bonded in chains Can have branching structures not usually soluble in water Glycogen- animal carbohydrate Polyglucose Starch- plant carbohydrate Polyglucose Cellulose- plant polymer Polyglucose but indigestible = fiber

2 Unit 2 Insoluble in water = hydrophobic Triglycerides Phospholipids Cholesterol Steroids Fatty acids Fat soluble vitamins

2 Unit 2 Ring structures Used to make steroid hormones Help make membranes stiff Made in liver

2 Unit 2 Structural elements in cells Chemical catalysts Hormones Antibodies Polymers of amino acids

2 Unit 2 Amino group Carboxyl group Side chain ~20 different side chains A large variety of structures

Figure 2.13

2 Unit 2 Amino acids joined by peptide bond 2 = dipeptide, 3= tripeptide Many =polypeptide Functional polypeptide = protein Includes structure up to quaternary. Thus a protein may have 1 or more polypeptide chains

2 Unit 2 Proteins serving as chemical catalysts Highly specific Efficient May be controlled

Figure 2.14

2 Unit 2 Polymer of nucleotides => Phosphate Sugar –pentose (ribose, deoxyribose) Base- 5 of them (4 per nucleic acid) Adenine (A), guanine (G), thymine (T), cytidine (C), uracil (U)

2 Unit 2 Deoxyribose & A,T,G,C Bases pair: A-T & G-C Two polymers hydrogen bonded together forms a double helix Stores genetic information on protein sequences.

2 Unit 2 Ribose & A,U,G,C Single chain Functions in protein synthesis Required to translate DNA to protein

2 Unit 2 Specialized for energy transport in the cell Carries energy in the chemical bond between phosphate groups.