Chapter 2 The Chemistry of Life

The 4 organic molecules found in living things 1.Carbohydrates = C-H-O 2.Lipids = C-H-O 3.Nucleic Acids = P-C-H-O 4.Proteins = N-H-O-C

Chemistry What is the chemistry of “life”? Twenty-five chemicals are necessary for life and four create about 96 % of living matter: 1.Carbon 2.Oxygen 3.Hydrogen 4.Nitrogen. COHN The Atom and Periodic Table

Atoms Democritus coined the term atom 2500 years ago What is an atom made of? What is atomic number? What is atomic mass? Electrons, Protons, Neutrons # of protons Average number of protons & neutrons

Isotopes & Element Isotope - different number of neutrons Do isotopes act differently in chemical reactions? How are radioactive isotopes used? (Geological Dating, Bacteria, Cancer, Tracers or Markers) What is an element? 1. An material which cannot be broken down or changed into another substance using chemical means. The basic chemical building blocks of matter. What makes elements different from each other? 2. The number of protons in the nucleus

Forces of Nature 4 Forces 1.Electromagnetism 2.Strong or Nuclear Force between protons & neutrons 3.Weak – decay of an atom (alpha, beta, gamma) 4.Gravity – the force exerted between two objects God Particle

Radioactive Decay 1. Alpha Decay alpha particle emitted = (2 protons and 2 neutrons) 2. Beta Decay A. Beta Minus - Neutron turns into a proton + electron + antineutrino – Last two emiited B. Beta Plus - Neutron turns into a proton + positron + neutrino – last two emitted 3. Gamma Decay – nucleus emits photons Nucleus moving from high to lower state of energy

Compounds & Bonds Compounds - two or more elements chemically bonded Molecule - smallest unit of a compound that is still exhibiting the compounds properties Valence Electrons - form bonds – what is stable? Ionic Bonds - transfer of electrons - resulting in ions Covalent Bonds - shared electrons

Van der Waals Forces Variances in charges causing attraction & weak bonds Geckos and surface area in their feet

Water What makes water so great? Hydrogen Bonding ature=related

Properties of Water – Blue Planet – ever wonder why? Density Polarity Hydrogen Bonds High Specific Heat Capacity: 1g H 2 O/1degree celsius Cohesion Adhesion Universal Solvent Mixture - two or more elements not chemically combined 1.Solution - Universal Solvent - ions disperse 2.Suspensions - blood - movement keeps larger particles afloat throughout the fluid

pH - "Potential Hydrogen” What is the pH scale? A scale from 0 to 14 reflecting the concentration of hydrogen ions in solution; pure water has a pH value of 7, acids have a lower value and bases higher. pH levels affect the conformational state (optimum 3D formation) of the enzyme. What is an acid and what is a base? Acids are compounds that contain hydrogen and can dissolve in water to release hydrogen ions into solution. HCl disolved in H 2 O = H + (aq) + Cl - (aq) Bases are compounds that dissolve in water to release hydroxide ions (OH-) into solution. NaOH disolved in H 2 O = Na + (aq) + OH - (aq) What is a buffer? A buffer solution is one which resists changes in pH when small quantities of an acid or a base are added to it.

pH & Blood Your blood's pH is normally at 7.4 Lungs – carbon dioxide (CO 2 ) Kidneys - bicarbonate (HCO 3 ) ammonia (NH3) / ammonium (NH4+) Alkalosis pH rises above 7.45 Too Little CO 2 & Too Much HCO 3 Associated with electrolyte disturbances caused by prolonged vomiting, severe dehydration, or hyperventilation Body interprets low carbonic acid concentrations as a sign of high oxygen concentrations, so it constricts blood vessels to reduce oxygenation. Acidosis pH falls below 7.35 Too much CO 2 & Too Little HCO 3 Body interprets high carbonic acid concentrations as a sign of low oxygen concentrations, so it dilates blood vessels to improve oxygenation. The HCO3/CO2 buffer system is extremely important because it can be rapidly readjusted in alkalosis and acidosis 1. H + (aq) + HCO 3 - (aq) ↔ H 2 CO 3 (aq) 2. CO 2 (aq) + H 2 O(l) ↔ H 2 CO 3 (aq)