unit 1 chemistry of life terms

polar vs. nonpolar

polar vs. nonpolar

• polar: one atom has greater electronegativity than the other → unequal sharing of electrons (water = polar)

• nonpolar: electrons are shared equally

hydrophilic vs. hydrophobic

• hydrophilic: water soluble, polar

• hydrophobic: do not dissolve in water, non-polar

covalent bond

• valence electrons shared by two atoms

hydrogen bond

• weak bonds formed between partial positive charged hydrogen atom and strong electronegative oxygen/nitrogen atom-

pH (acid, neutral, basic)

• acids: excess H+ ions, pH < 7

• bases: excess OH- ions, pH > 7

carbohydrates

• simple sugars (glucose, fructose, etc.), polymers (starch)

• monosaccharides (glucose), polysaccharides (starch, cellulose, glycogen)

• function: energy storage (starch, glycogen), structural support (cellulose, chitin)

• change the structure → change the function

lipids

• hydrophobic (ex. waxes, oils, fats, steroids)

• fats: 1 glycerol and 3 fatty acids

  • saturated: solid at room temp., no double bonds between carbons

  • unsaturated: liquid at room temp., C=C → kinks

• phospholipids: cell membrane

  • hydrophilic (polar) head, includes phosphate group

  • two hydrophobic (non-polar) fatty acid tails

• steroids

• function: energy storage, insulation, membrane

proteins

• polymers of amino acid monomers

  • amino acids: carboxyl group (COOH), amino group (NH2), r group

  • linked by peptide bonds

• 4 levels of structure

  • primary: unique amino acid sequence

  • secondary: (alpha helix: coiled, beta pleated sheet: accordion)

  • tertiary: complex (interactions between r groups)

  • quaternary: 2+ polypeptide chains into one protein (ex. hemoglobin)

• protein shape crucial to protein function

  • denatured (loses shape/function due to head, pH)

• function: enzymes, movement, membrane receptors

nucleic acids

• DNA (double stranded helix) and RNA (single-stranded)

• nucleotide monomers

  • nitrogenous base, pentose 5C sugar, phosphate group

• have directionality (DNA replication/transcription: 5’ to 3’)

• function: heredity, code for amino acid sequence

dehydration synthesis vs. hydrolysis

• dehydration synthesis: join monomers by removing water molecule

• hydrolysis: split polymers by adding water molecule