Lecture 6 Outline of Last Lecture Proteins:I. StructureII. Amino AcidsIII. Polypeptide ChainsIV. Levels of Protein StructuresV. Protein FunctionCarbohydrates:I. StructureII. MonosaccharideOutline of Current Lecture I. Nucleic Acidsa. Typesb. Flowc. Monomersd. Linkagee. Structure of DNAII. Lipidsa. Functionsb. Groupsc. Fatsd. Saturatede. Unsaturated BIOL 101 1st Editionf. Trans Fatg. Phospholipidsh. SteroidsCurrent LectureI. Nucleic Acidsa. Major Types – i. DNA – genetic materialii. RNA – making proteins1. rRNA  forms part of the structure of the ribosome2. mRNA  carries code for proteinb. Two ways it flows – i. Parent to offspringii. DNA  mRNA  proteinc. Monomers – Nucleotides that are made of 3 parts – i. “base” – 5-carbon sugar (ribose in RNA, deoxyribose in DNA)ii. phosphate group – covalently attached to carbon #5iii. Nitrogenous base – covalently bonded to carbon #1 1. Pyrimidines – 6 membered ring (cytosine [both], thymine [DNA], uracil [RNA])2. Purines – 5 membered ring fused to the six membered ring (adenine and guanine) [RNA & DNA]d. Linkage of nucleic acids – phosphodiester bond – i. Phosphate of one nucleotide & sugar of the nextii. Results in polynucleotide with repeated sugar-phosphate backboneiii. A nitrogenous base (A, G, C, T, U) is attached to each sugariv. RNA is a single polynucleotide chain with different ends (one with phosphate, one with hydroxyl)v. DNA is 2 polynucleotide chains w/own phosphate-sugar backbonevi. Connected by (3) hydrogen bonds (C to G, A to T)e. DNA Structure – i. Looks like a ladder1. Phosphate-sugar chains are uprights of ladder2. Hydrogen bonded nitrogenous bases are rungs of ladderii. Each has a 5’ end and a 3’ end1. 5’ end  free phosphate on carbon #52. 3’ end  -OH group on carbon #33. They run in opposite directions of each other with regard to the ends (anti-parallel)iii. Each sugar in both chains has one of 4 nitrogenous bases covalently attached1. A, T, C, Giv. Nitrogenous bases are hydrogen bonded to those on opposite strand (base pairing)1. A pairs with T, C pairs with Gv. Base pairs are ALWAYS the same (Chargoff’s Rule)vi. Two strands of DNA molecules are said to be complementary  held together by the base pairing rulevii. Whole DNA molecule is twisted in a helixviii. Sugar-phosphate chain is on the outside of helixix. Two strands are perfectly base-paired (complementary)II. Lipidsa. Functions: lipids are insoluble in water (not really macromolecules), 3 types – i. Structural (membranes)ii. Energy storage (fats, oils)iii. Hormonal (some steroids)b. Three major groups – i. Fats (oils)ii. Phospholipidsiii. Steroidsc. Fats (oils) – i. Made of glycerol & fatty acids (2 monomers: glycerol and fatty acids)ii. A.k.a.  triglycerideiii. Hook one fatty acid to each carbon in the glycerol molecule by dehydration synthesis forming an ester bondiv. Has hydrocarbon tail (12-24 carbons) that is NONPOLAR (insoluble in water)When complete, glycerol bonded to 3 nonpolar fatty acid tailsEster bonds are essentially the bond of oxygen to carbon between the glycerol and fatty acid tailsd. Saturated – i. No double bonds between carbons in fatty acidsii. Molecules are flexibleiii. Pack closely together, therefore SOLID at room temperatureiv. Most animal fats are saturated (lard, butter, bacon grease)e. Unsaturated – i. Molecules have one or more double bonds in the fatty acid tailii. The tail becomes kinked (tail is not straight or consistent in structure) at each double bondiii. Molecules can not pack closely together because of kinks, therefore LIQUID at room temperatureiv. Most plant oils are unsaturated (corn oil, olive oil)v. Same is true of fish oil (cod oil, liver oil)f. Trans Fat – i. Natural unsaturated fats typically in the “CIS” configuration (both hydrogens are on the same side of the double bond of carbon)ii. This results in the “kink” making it liquid at room temperatureiii. When unsaturated vegetable oil is chemically modified by hydrogenation, it causes someof the fatty acid tails to become saturated (losing their double bonds)iv. However, hydrogenation causes trans double bondsv. Trans double bonds don’t cause natural kinks  trans bond instead, hydrogens aren’t onthe same side of the carbon double bondvi. Saturated fats and trans fats are linked to heart disease because animals (humans) can not process them in their bodies, but ESPECIALLY trans fatsg. Phospholipids – i. Major constituents of cell membranesii. Structure is similar to fats except:1. Glycerol molecules has only TWO fatty acids attached2. The third carbon of the glycerol has a phosphate attached INSTEAD of a third fatty acid (like in fats)3. The phosphate group on the third carbon has an additional group attached that is ALWAYS polar (charged)iii. Phospholipids are amphipathic  water loving (the head) AND water fearing (the fatty acid tails)h. Steroids – i. 4 fused carbon rings with various functional groups attachedii. Precursor to many other steroids including sex hormonesiii. Common component of cell membranesiv. Cholesterol is an example of a steroidThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a