Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Basic Chemistry Chapter 2 Chemistry of Life • All life processes involve chemical reactions (clinical day) – Ex. Ca++ in muscle contraction Na+, K+ in nerve impulses Matter • anything that has mass and takes up space • can you think of solids, liquids, and gases that might be found in the body? Energy • the capacity to do work • No mass & does not take up space • Types: – Potential: stored in bonds (chemical) – Kinetic: doing work (electrical, mechanical, radiant) • Exergonic & endergonic reactions Composition of Matter • 92 naturally occurring elements (112 known, 113118 are alleged) • Living organisms require about 26 of these elements (table 2.1, p.28) • About 96% (by mass) comes from Oxygen (O), Carbon (C), Hydrogen (H), and Nitrogen (N) Atoms • smallest complete unit of an element – Composed of dozens of subatomic particles, but we are only concerned with THREE! Subatomic Charge Location Particle What it tells you! Proton + Nucleus Identity of atom, mass Neutron 0 Nucleus Isotope, mass Electron - Surrounds nucleus Properties of atom, negligible mass Identifying Elements • Atomic number • equal to the number of protons in an atom (& electrons in neutral atom!) • Atomic mass • sum of the masses of all the protons & neutrons contained in nucleus Isotopes • atoms of same element with a different mass (due to neutrons) but same chemical properties • Ex. C-12 and C-14 • Radioactive isotopes used in many medical tests to tag biological molecules to be followed or traced • i.e. PET scans, I-131 for thyroid activity, destroying localized cancers (Ra, Co, etc.) Ions • • • • Charged particles Form ionic bonds Cations (+) Anions (-) Find the Face (in the Beans) Chemical Bonds • Transfer or share electrons in order to fill their valence shell (stability) • All atoms want 8 e- in their valence shell (except H & He) • Ionic bond – transfer electrons • Covalent bond – share electrons – Nonpolar: shares electrons equally – Polar: shares electron unequally Chemical Bonding • Due to electronegativity – How much an atom in a bond pulls electrons to itself – Ionic: >1.7 – Polar covalent: 0.4-1.7 – Covalent: <0.4 Hydrogen Bonding • Weak bonds • attraction of H to partial negative charge – Example: polar covalent bonds between oxygen and hydrogen Molecular Formula • represents the numbers and types of atoms in a molecule – Ex. H2O , C6H12O6 Chemical Reactions • Metabolism= sum of all chemical reactions in the body – Synthesis (anabolism) A+B AB • Energy absorbing • i.e. growth, repair, protein synthesis – Decomposition (catabolism) AB A+B • Energy releasing • i.e. digestion of foods, breakdown of glycogen in liver to produce glucose – Single replacement – Double replacement AB + C AB + CD AC + B AD + CB Rate of Chemical Reactions • Temperature ( temp increases collisions) • Concentration of reactants ( number = faster, more collisions) • Particle size (smaller = faster, more collisions) • Presence of catalysts – Affect rate of reaction without being changed by reaction – Biological catalysts: enzymes (proteins) – Shape matters! Like a puzzle piece Biochemistry • Inorganic compounds: lack carbon (with few exceptions) – Small, simple molecules – Water, salts, many acids & bases • Organic compounds: carbon-containing compounds – Large covalently bonded molecules – Carbohydrates, lipids, proteins, nucleic acids Inorganic Compounds • Water – High heat capacity • Absorbs & releases large amounts of heat • Prevents sudden changes in body temperature (homeostasis!) – Polarity/solvent properties • • • • “universal solvent” Chemical reactions depend on solvent Transport/exchange medium Lubrication (synovial fluid in joints) – Chemical reactivity (hydrolysis reactions) – Cushioning • Protective (CSF, amniotic fluid) Inorganic Compounds • Oxygen – used to release energy from glucose • Carbon dioxide – waste of metabolic processes Inorganic Compounds • Salts – Ionic compound containing cations other than H+ and anions other than OH– Vital to body functions • K+ & Na+ essential for nerve function, Fe2+ is essential for hemoglobin, Cl-, Ca++, Mg++, PO4-, CO3-, etc. – All salts are electrolytes (substances that conduct an electrical current in solvent) • Release ions when dissolved in water – Functions in Table 2.1, page 28 Inorganic Compounds • Acids & Bases – Electrolytes • Acids – Release H+ ions in solution – “proton donors” – HCL, acetic acid, carbonic acid • Bases – Release OH- ions in solution – “proton acceptors” – HCO3- (important base in blood) • pH scale measures hydrogen ion concentration – pH 7 = neutral – pH >7= basics (more OH- than H+) – pH <7= acidic (more H+ than OH-) • Normal blood pH for humans is 7.35 to 7.45 – If > , alkalosis – If < , acidosis • Buffers- maintain pH Organic Compounds Carbohydrates • sugars, starches, glycogen, cellulose – 2-3% body weight – Plants- starches and cellulose (cannot digest) – Animals- source of energy- stored as glycogen Carbohydrates • Monosaccharides: 3 to 7 carbons – Ex. Glucose, fructose, galactose Many C6H12O6 • Carbohydrate utilized by the cell Carbohydrates • Disaccharides: 2 monosaccharides combine by dehydration synthesis (condensation) – Ex. Sucrose • Broken apart by hydrolysis (add water) Carbohydrates • Polysacchride: 10-100s of monos – Ex. starch Lipids • 18-25% in lean adults – Contain C, H, O - neutral – Fats- concentrated energy stored in adipose tissue Lipids • Triglycerides: Glycerol + 3 fatty acids • Monounsaturated- one double bond • Polyunsaturated- more than one double bond • Saturated- no double bonds Lipids • Phospholipidspolar head and 2 non-polar tails (membrane) Lipids • Steroids- cholesterol, sex hormones, cortisol, etc. Proteins • 12-18% in lean adults – Structural and physiological enzymes – Made of amino acids (20)- held by peptide bonds – 3D shape held by H-bonds (denatured with heat) Nucleic Acids – Base + sugar + phosphate – DNA and RNA – ATP- provides energy for the cell Isomers • molecules with the same chemical formula and with the same kinds of bonds between atoms, but in which the atoms are arranged differently. • share similar if not identical properties in most chemical contexts.