BIOL 101 1st Edition Lecture 6 Outline of Last Lecture Proteins I Structure II Amino Acids III Polypeptide Chains IV Levels of Protein Structures V Protein Function Carbohydrates I Structure II Monosaccharide Outline of Current Lecture I Nucleic Acids a Types b Flow c Monomers d Linkage e Structure of DNA II Lipids a Functions b Groups c Fats d Saturated e Unsaturated f Trans Fat g Phospholipids h Steroids Current Lecture I Nucleic Acids a Major Types i DNA genetic material ii RNA making proteins 1 rRNA forms part of the structure of the ribosome 2 mRNA carries code for protein b Two ways it flows i Parent to offspring ii DNA mRNA protein c 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 5 iii 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 next ii Results in polynucleotide with repeated sugar phosphate backbone iii A nitrogenous base A G C T U is attached to each sugar iv 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 backbone vi Connected by 3 hydrogen bonds C to G A to T e DNA Structure i Looks like a ladder 1 Phosphate sugar chains are uprights of ladder 2 Hydrogen bonded nitrogenous bases are rungs of ladder ii Each has a 5 end and a 3 end 1 5 end free phosphate on carbon 5 2 3 end OH group on carbon 3 3 They run in opposite directions of each other with regard to the ends antiparallel iii Each sugar in both chains has one of 4 nitrogenous bases covalently attached 1 A T C G iv Nitrogenous bases are hydrogen bonded to those on opposite strand base pairing 1 A pairs with T C pairs with G v 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 rule vii Whole DNA molecule is twisted in a helix viii Sugar phosphate chain is on the outside of helix ix Two strands are perfectly base paired complementary II Lipids a 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 Phospholipids iii Steroids c Fats oils i Made of glycerol fatty acids 2 monomers glycerol and fatty acids ii A k a triglyceride iii Hook one fatty acid to each carbon in the glycerol molecule by dehydration synthesis forming an ester bond iv Has hydrocarbon tail 12 24 carbons that is NONPOLAR insoluble in water When complete glycerol bonded to 3 nonpolar fatty acid tails Ester bonds are essentially the bond of oxygen to carbon between the glycerol and fatty acid tails d Saturated i No double bonds between carbons in fatty acids ii Molecules are flexible iii Pack closely together therefore SOLID at room temperature iv Most animal fats are saturated lard butter bacon grease e Unsaturated i Molecules have one or more double bonds in the fatty acid tail ii The tail becomes kinked tail is not straight or consistent in structure at each double bond iii Molecules can not pack closely together because of kinks therefore LIQUID at room temperature iv 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 temperature iii When unsaturated vegetable oil is chemically modified by hydrogenation it causes some of the fatty acid tails to become saturated losing their double bonds iv However hydrogenation causes trans double bonds v Trans double bonds don t cause natural kinks trans bond instead hydrogens aren t on the same side of the carbon double bond vi Saturated fats and trans fats are linked to heart disease because animals humans can not process them in their bodies but ESPECIALLY trans fats g Phospholipids i Major constituents of cell membranes ii Structure is similar to fats except 1 Glycerol molecules has only TWO fatty acids attached 2 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 attached ii Precursor to many other steroids including sex hormones iii Common component of cell membranes iv Cholesterol is an example of a steroid These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute