Basic Chemistry Chapter 2 Chemistry of Life All

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 link

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!! • Strong force!! • 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. H 2 O , C 6 H 12 O 6

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. link

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 + 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 – Cohesion and Adhesion= High surface tension – 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, Fe 2+ is essential for hemoglobin, Cl-, Ca++, Mg++, PO 4 -, CO 3 -, 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” – HCO 3 - (important base in blood)

• p. H scale measures hydrogen ion concentration – p. H 7 = neutral – p. H >7= basics (more OH- than H+) – p. H <7= acidic (more H+ than OH-) • Normal blood p. H for humans is 7. 35 to 7. 45 – If > , alkalosis – If < , acidosis • Buffers- maintain p. H

Organic Compounds s e t a r d y h o b r a Lipids C Prot eins s d i c A c i e l Nuc

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 C 6 H 12 O 6 • 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 -100 s of monos – Ex. Starch, cellulose, glycogen, chitin

Lipids • 18 -25% in lean adults – Contain C, H, O – neutral (much less O) – 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. • 4 rings

Proteins • 12 -18% in lean adults – Contain C, H, O, N – Structural and physiological enzymes – Made of amino acids (20)- held by peptide bonds – 3 D shape held by H-bonds – (denatured with heat)

Nucleic Acids – Contain C, H, O, N, P – Base + sugar + phosphate (nucleotide) – DNA and RNA – ATP- provides energy for the cell

link