nucleic acids - information storage devices of cells; 2 varieties  

• can serve as templates to create exact copies of themselves
• deoxyribonucleic acid (DNA) - the hereditary material
• ribonucleic acid (RNA) - used to read DNA in order to create proteins; used as a blueprint to create amino acid sequences
• finally able to be seen w/ scanning-tunneling microscope

nucleotides - subunits of nucleic acids  

• contains 5-carbon sugar, phosphate group, organic base
• purine - large, double-ring molecules; adenine, guanine (both in RNA/DNA)
• pyrimidine - smaller, single-ring molecules; cytosine (in RNA/DNA), thymine (in DNA only), uracil (in RNA only)

DNA  

• made of difference combinations of 4 types of nucleotides (adenine, guanine, cytosine, thymine)
• 2 chains wrap around each other like a staircase (double helix shape)
• hydrogen bonds hold 2 chains together
• adenine only complementary to thymine (in DNA), uracil (in RNA)
• cytosine only complementary to guanine

RNA  

• uses ribose sugar instead of deoxyribose (in DNA)
• has hydroxyl group where a hydrogen is in DNA >> stops double helix from forming
• uses uracil in place of thymine (has 1 more methyl group than uracil)
• usually single-stranded (differentiates itself from double-stranded DNA); serves as a transcript of the DNA
• evolved into DNA to protect the hereditary material from single-strand cleavage
• "central dogma" of molecular biology - flow of info from DNA to RNA to protein

ATP - adenosine triphosphate (contains adenine, a nucleotide)  

• energy currency of the cell
• tinamide adenine dinucleotide (NAD+), flavin adenine dinucleotide (FAD) both carry electrons to make ATP

lipids - insoluble in water  

• most familiar forms are fats/oils
• very high proportion of nonpolar carbon-hydrogen bonds
• can't fold up like proteins
• spontaneously exposes polar parts and moves nonpolar parts within when placed in aqueous environment

phospholipids - form the core of all biological membranes  

• glycerol - 3 carbon alcohol; forms the phospholipid's backbone
• fatty acid - long chains of CH2 groups, ending in a carboxyl; 2 chains
• phosphate group - attached to an end of the glycerol; usually has an organic molecule attached to it
• phosphate group serves as the polar "head"; fatty acids serve as the nonpolar "tails"
• micelle - spherical forms w/ the tails pointed inward
• phospholipid bilayer - 2 phospholipid layers w/ the tails pointed towards each other; basic framework of biological membranes

fats - do not have a polar end like phospholipids  

• contains 3 fatty acids
• aka triglyceride, triacylglycerol
• fatty acids don't need to be identical
• energy stored in the C-H bonds of fats
• clump together in water to form globules since they lack polar ends
• saturated fats - carbon atoms in fatty acids each bonded to at least 2 hydrogen
• unsaturated fats - has double bonds between 1+ carbon atoms
• polyunsaturated fats - has more than 1 double bond; have lot melting points (usually liquid at room temperature)
• terpene - long-chain lipids usually found in chlorophyll and visual pigment retinal
• steroid - has 4 carbon rings; can function as hormones
• prostaglandins - about 20 lipids acting as chemical messengers, with 2 nonpolar tails attached to a five-carbon ring

fats as energy-storing molecules  

• fats contain about 40 carbon atoms
• ratio of C-H bonds to carbon atoms in fats is 2x the ratio of carbohydrates
• animals produce mostly saturated fats
• plants produce mostly unsaturated fats
• adding hydrogen can convert an oil into solid fat
• hydrogenating oils into solids turns unsaturated fats into saturated
• excess carbohydrates get converted into fats, starch, glycogen
• plaque - deposits of fatty tissue found on blood vessel lining; broken pieces can cause strokes, block blood flow