BIOL 120 1st Edition Lecture 7 Outline of Last Lecture I Nucleic Acids Nucleotides a Nucleotides nucleic acid purines pyrimidines phosphorylation II Structure of DNA III Structure of RNA IV Lipids beginning a Lipids saturated unsaturated monounsaturated polyunsaturated Outline of Current Lecture I Lipids continued II Lipids structure a phospholipids glycerol phospholipids amphipathic III Proteins key concepts IV Structure a peptide bond polypeptide N terminus C Terminus V Protein functions Current Lecture I Lipids A Fatty Acids 1 simplest lipid a long hydrocarbon chain hydrophobic with a carboxyl group at one end 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 2 Stored as fats and provide a large amount of energy insoluble a provide more energy than carbs or sugars B Good Fats 1 monounsaturated fat poly unsaturated fats and omega 3 fatty acid a all fats are a mixture of fats 2 Good Oils plant based fat generally better for health a i e almond oil avocado oil canola oil C Bad Fats 1 Bad oils a i e palm oil and coconut oil semi solid and full of saturated fat but the good kind 2 Trans fat industrially produced contains trans isomer fatty acids II Lipids structure A Phospholipids 1 Phospholipids consist of 2 fatty acids joined to a polar head phosphate and are the principal components of cell membranes a form a bilayer membrane and the tails hydrophobic of fatty acid touch and heads hydrophilic are opposite each other b Amphipathic part water soluble and part water insoluble hydrophilic and hydrophobic 2 Glycerol phospholipids 2 fatty acids are bound to carbon in glycerol 3 Cell membranes also contain glycolipids sugar and fat and cholesterol a Cholesterol made up of 4 hydrocarbon rings that are hydrophobic and a hydrophilic OH on one end amphipathic i comes from animal source and bad cholesterol b Phytosterol comes from plant membrane is a good cholesterol B Membrane structure 1 made from a bilayer of phospholipids and associated with proteins a also known as the fluid mosaic model of membrane structure Jonathan Singer and Garth Nicolson b nonpolar parts of membrane face inwards and polar parts of the membrane face outwards polar heads can work with water which is what the cell mostly consist of III Protein Key concepts 1 cell functions depend on proteins 2 protein is composed of amino acids made from RNA in the cytoplasm 3 Amino acids vary in function and structure 4 Levels of protein structure hierarchy system a Primary amino acid sequence b Secondary amino acids form alpha helices twist or beta pleated sheets through folding i hydrogen bonds connect the COO group of one amino acid with the NH3 group of another c Tertiary amino acids dictate protein s overall shape i bonds that are used hydrophobic interaction van der Waals interactions Covalent disulfide bonds ionic bond d Quaternary proteins combine to make up a larger molecule that is the functional structure 5 Proteins are in charge of cell function IV Structure A structure of amino acids 1 all proteins made from 20 amino acids 2 All amino acids have a central carbon atom b amino group NH2 c Carboxylic group COOH d R group side chain determines the different amino acids only thing different in structure i four groups non polar polar acidic basic 3 In water a amino acid and carboxyl group ionize to NH3 and COO become more reactive B Bonds 1 Peptide bond condensation reactions bond the carboxyl group of one amino acid to the amino group of another a polypeptide a chain of amino acids linked by peptide bonds i contain fewer than 50 amino acids olihopeptides ii contain more than 50 amino acids proteins b Polypeptide characteristics i R group orientation ii Directionality N terminus free amino group on left C Terminus free carboxyl group on right iii Flexibility V Protein Functions A Catalysis use enzymes to speed un reactions B Defense attack pathogens with antibodies and complement proteins C Movement motor and contractile proteins move the cell and molecules within the cell D Signaling proteins send messages between cells E Structure define shape of cell and comprise body structures F Transport membrane proteins monitor and control molecular movement in and out of cell and transport proteins carry materials