chapter 2

• Composed of protons, neutrons and electrons
• Nucleus contains protons (+charge) and neutrons (no charge)
• Electrons(- charge) occupy orbitals or shells outside nucleus

sum of protons and neutrons in an atom

number of protons in an atom

layers around the nucleus

• those in outermost shell
• participate in chemical reaction and form bonds

• different forms of same atom
• Atomic number is the same, but atomic mass is different
• contain different numbers of neutrons

• Occur when atoms share valence electrons
• nonpolar - e are shared equally (H₂ and O₂)
• polar - electrons are shared unequally (H₂0)

• when valence electrons are transferred from one atom to another form charged ions
• Atom that loses electrons becomes cation (+charged)
• Atom that gains electrons becomes anion (- charged)

molecules are soluble in water because readily form hydration spheres

• molecules are nonpolar,
• cannot form hydration spheres

When H forms polar bond with another atom it takes on a slight + charge making it attracted to any nearby negatively charged atoms

Adjacent H₂0 create surface tension

release protons (H+) in a solution (proton donor)

lower H+ levels of a solution (proton acceptor)

H20 + C02 Û H2C03 Û H+ + HC03-

occurs if pH < 7.35

occurs if pH > 7.45

• carbonyl group - ketones and aldehydes
• hydroxyl group - alcohols
• carboxyl group - organic acids (lactic and acetic acids)

• Differ in spatial orientation of a functional group
• D isomers - right-handed
• L isomers - left-handed

• simple sugars such as glucose, fructose, galactose
• Only glucose is used as “metabolic fuel”

• Sucrose - table sugar (=glucose + fructose)
• Lactose - milk sugar (=glucose + galactose)
• Maltose - malt sugar (=2 glucoses)

• many monosaccharides linked together
• Include starch and glycogen

• Is reverse of dehydration synthesis
• H+ added to one monosaccharide, OH- to other -- called hydrolysis

condensation of 1 glycerol and 3 fatty acids

hydrocarbon chains of fatty acids are joined by single covalent bonds

there are double bonds within hydrocarbon chains

• 1 c=c with Hydrogens that share the double
• bond on same side of fatty acid chain
• This configuration makes the fatty acid bend

• 1 c=c with Hydrogens that share the double bond on opposite sides of fatty acid chain
• This configuration makes the fatty acid straight

• acidic, high lvl cause ketosis
• Ketoacidosis occurs when ketone bodies in blood lower pH

• lipids that contain a phosphate group
• Phosphate part is polar and hydrophilic
• Lipid part is nonpolar and hydrophobic

• three 6-carbon rings joined to a 5-carbon ring
• Cholesterol is precursor for steroid hormones
• Is component of cell membranes

• fatty acids with cyclic hydrocarbon group
• Produced by and active in most tissues
• serve many regulatory functions

• made of long chains of amino acids
• contain an amino group (NH2) at one end; carboxyl group (COOH) at other end

• short chains of amino acids, linked by peptide bonds
• Formed by dehydration reactions

<100 amino acids

>100 amino acids

sequence of amino acids

• caused by weak H bonding of amino acids
• Results in alpha helix or beta pleated sheet shapes

• caused by bending and folding of polypeptide chains to produce 3-dimensional shape
• Formed and stabilized by weak bonds between functional groups
• can be denatured by heat, pH

forms when a number of polypeptide chains are covalently joined

• Include DNA and RNA
• made of long chains of nucleotides
• consist of a 5-carbon sugar, phosphate group, and nitrogenous base
• Bases are pyrimidines (1 ring) or purines (2 rings)