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Ch. 2 Chemical Level of
Organization
Interactive pages 27-58
Atoms, Molecules, & Bonds
 Atoms are the smallest
stable unit of matter
Protons +charge, in the
nucleus of the atom
Neutrons 0charge, also in the
nucleus
Electrons –charge, 1/1836 the
mass of a proton
 Atomic Structure
Atomic #= # of Protons
Electron cloud (orbiting eoutside the nucleus)
Elements and Isotopes
 Elements are made of the same atom
 Isotopes- atoms of the same element with
differing numbers of neutrons
Mass #= the total number of neutrons + the total number
of protons
Atomic weight- avg. mass of all isotopes of that element
(including electrons)
Radioisotopes emit subatomic particles or radiation
(radioactive decay)
 Half life is the time required for ½ of the given amount of
isotope to decay
Electrons & Energy Levels
Electrons occupy a series of energy levels
1st shell (closest to the nucleus): holds 2
electrons and has the lowest energy
2nd energy level: holds up to 8 electrons
3rd: up to 18 electrons
Outermost energy level is the surface of the
atom and determines bonding or chemical
properties of that element
Chemical Bonds
 How elements are held together or interact
Ionic
 Electron Donor & Electron Acceptor
 NaCl
Covalent
 Share e- to form a molecule
 Single, double, or triple bonds
 Non-polar= equal sharing of electrons
 Polar: unequal sharing of electrons H20
Hydrogen
 Bonds between H+ and – N or O ends of adjacent
molecules
 Creates surface tension
Chemical Reactions
When new bonds form or break between
atoms
Reactants Products
Reactions in cells or tissue constitute
metabolism
Activation energy: amount of energy
needed to start a reaction
Enzymes (proteins): reduce activation energy;
they are catalysts (speed up reaction)
Types of Reactions
 Decomposition
Hydrolysis-break down by adding
water
Catabolism- break down of complex
molecules in the body (releases
energy)
 Growth, movement, reproduction
 Synthesis
Dehydration or condensation
Anabolism: synthesis of new
molecules within the cells of the
body (requires energy)
Inorganic Compounds
Part II
Nutrients
 Essential elements obtained from diet
 Metabolites: molecules that can be synthesized
or broken down in our bodies
Inorganic-no Carbon or Hydrogen in primary structure
 Most important in body
CO2
O2
H2O
Acids, bases, & Salts
Water
 Properties
 Solubility (universal solvent due to polarity)
 Reactivity (dehydration & hydrolysis)
 High Heat Capacity (retains lots of heat before changing state):
perspiration
 Lubrication (little friction between molecules
 Aqueous solutions
 Ionic bonds dissociate in water and create ions (conduct
electricity)
 Electrolytes: inorganic molecular ions in the body vital to function &
regulated by the kidneys, digestive system, & skeletal system
 Colloid: solution with dispersed proteins & large particles
 Suspension: large particles that may settle out of solution (blood)
pH
 Dissociation of H+ ions in water making H+ and
OH- (hydroxide)
Neutral= 7 (pure water) equal amounts of H+ and OHAcidic= 7 more H+ than –OH
 Acids- proton donors releases H+ in solution (HCL)
 Bases- proton acceptor releases –OH in solution (NaOH)
Basic= 7 less H+ than –OH (A.K.A. Alkaline)
Blood has a pH of 7.35-7.45
 Higher pH results in uncontrollable muscle contractionsAlkalosis
 Lower pH can result in coma- Acidosis
Salts: Inorganic compounds made of any cation except
H+ and any anion except –OH (NaCl)
Buffers: stabilize pH, usually a weak acid combined
with a related salt (NaHCO3- sodium bicarbonate)
Organic & High Energy
Compounds
Part III
Carbohydrates
 C,H,O in a 1:2:1 ratio
 Sugars and Starches
 Water soluble
(hydrophilic)
 Monosaccharide: simple
sugars
 Disaccharides: sucrose
 Polysaccharides:
cellulose, starch, &
glycogen (stored in
muscle)
Lipids

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

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
Fats, oils, & waxes
C,H, O (less O than in carbs)
Most insoluble in water (Hydrophobic)
Twice as much energy as carbs
Glycerol & a fatty acid chain (saturated or unsaturated)
Eicosanoids: prostigalandins released by damaged
tissue to stimulate nerve endings
 Glycerides: energy source, insulation, protection
 Steroids
 Cholesterol: maintains cell membranes
 Steroids: regulation of development and tissue metabolism
 Phospholipids: maintain membranes
Proteins
 Most abundant organic compound of the body (20%
body weight)
 C, H, O, N
 2 million different
 Functions: support, movement, transport, buffering,
metabolic regulation, coordination, control, defense
 Structure:
 Amino group
 Carboxylic acid group
 R-group
Nucleic Acids
C, H, O, N, P
Store and process information in the cell
DNA & RNA
Subunits or monomers called nucleotides
Nucleotide made up of a pentose (5 C
sugar), phosphate group, and nitrogenous
base
Adenine, guanine, cytosine, and thymine (or
uracil in RNA)
High Energy Compounds
Covalent bond that harnesses energy
ADP (adenosine diphosphate)
Undergoes phosphorylation (attachment of
a phosphate group)
Requires phosphate group
Enzyme to catalyze reaction
Organic substrate to add phosphate to
Becomes Adenosine Triphosphate (ATP)
When phosphate is removed energy is released