Basic ChemistryChapter 2

Chemistry of Life• All life processes involve chemical

reactions (clinical day)– Ex. Ca++ in muscle contraction

Na+, K+ in nerve impulses

• anything that has mass and takes up space

• can you think of solids, liquids, and gases that might be found in the body?

Matter

• 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

Energy

Composition of Matter• 92 naturally occurring elements (112 known, 113-

118 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 Particle

Charge Location 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)

• 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 Bonds

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

• represents the numbers and types of atoms in a molecule– Ex. H2O , C6H12O6

Molecular Formula

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 AB + C AC + B

– Double replacement AB + CD 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)

• 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

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

• 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

• Carbohydrateutilized by the

cell

Many C6H12O6

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

Carbohydrates

• 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

• Phospholipids- polar head and 2 non-polar tails (membrane)

Lipids

• Steroids- cholesterol, sex hormones, cortisol, etc.

Lipids

• 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)

Proteins

– Base + sugar + phosphate

– DNA and RNA– ATP- provides energy

for the cell

Nucleic Acids

• 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.

Isomers