Objectives for the Cumulative Final Material related to Exam 1 Know the number of bonds that can be formed by hydrogen carbon oxygen nitrogen and phosphorus Hydrogen can form one bond Nitrogen can form one to four bonds Oxygen can form one to four bonds Phosphorus can form one to five bonds Sulfur can form one to six bonds This can be determined by looking at the amount of valence electrons Understand the differences between covalent polar and nonpolar ionic hydrogen bonds and Van der Waals interactions and know which bonds are strongest and which are weakest Non polar covalent bonds electrons are shared equally examples H H O O C H Polar covalent bonds one atom has the electron more often atom that pulls the electron hardest is more electronegative examples O H N H C O Ionic Bonds when an electron is stolen by one atom from another example NaCl table salt Each atom has one full charge and the atoms are held together by electrical attraction Hydrogen bonds electrical attraction between compounds held together by polar covalent bonds Van der Walls Interactions weak attraction of uncharged atoms Know that O H and N H and C O covalent bonds are polar with the oxygen and nitrogen holding a partial negative charge and the hydrogen or carbon having a partial positive charge C C and C H covalent bonds are nonpolar Understand the concepts molecular weight mole molarity and be able to calculate how many grams of a substance should be dissolved in a given volume of water to make a solution of a certain molarity Molecular weight sum of the atomic weights of atoms in a molecule Mole amount of a compound equal to its molecular weight in grams Concentration Molarity is the measure of the moles i e molecules of a solute dissolved in a liter of a solution 1 M 1 mole L 6 x 1023 molecules of solute in a liter of water Know and understand the terms hydrophobic and hydrophilic be able to predict whether a molecule is hydrophilic or hydrophobic based on its molecular structure Hydrophilic water loving substances dissolve readily in water Molecules that have polar covalent or ionic bonds Hydrophobic substances do not dissolve in water Nonpolar substances nonpolar covalent bonds Know what an acid and a base is and understand the concepts of pH and pH scale be able to convert pH values into hydrogen ion concentrations Base a substance that dissolves and produces a hydroxyl ion or any substance that can except protons Acid any substance that will dissolve in water yeilding H and an anion or any substance that can donate protons in a reaction Know what a buffer is and understand how buffers control pH Buffers substances which minimize changes in pH Buffers are substances that gain or lose protons depending on pH Example Weak acids and bases are buffers Know the structure and general chemical activities of the major reactive groups on organic molecules OH hydroxyl basic hydrogen bonding CO CHO carbonyl hydrogen bonding NH2 amine basic hydrogen bonding COOH carboxyl acidic P04 phosphate charged and high energy bonds SH sulfhydryl reactive important in protein structure CH3 methyl non reactive and nonpolar Be able to distinguish carbohydrates sugars lipids and amino acids from their structural formulas Carbohydrates ringed sugars Lipids are hydrophobic because they consist mostly of hydrocarbons which form nonpolar covalent bonds Amino Acids Amino acids are joined by peptide bonds carbon Amino group Carboxyl group Know what a monosaccharide disaccharide and polysaccharide are that glucose is a 6 carbon monosaccharide The simplest carbohydrates are monosaccharides or single sugars molecular formulas x CH2O Disaccharides are double sugars Polysaccharides are polymers composed of many sugar building blocks Know that glucose forms two important polysaccharides starch glycogen and cellulose Starch is used for energy storage and that cellulose is used in plants to build cell walls has a structural role Starch Polymer of glucose Plants store stockpiles of glucose in the form of starch in chloroplasts Two forms o Amylose linear chain of 1 4 glycosidic linkages o Amylopectin branched has additional 1 6 linkages Animal counterpart of starch Stockpile of glucose stored mostly in liver and muscle cells Very similar to amylopectin only more highly branched Glycogen Cellulose Cellulose is a major structural component of the tough wall of plant cells Like starch cellulose is a polymer of glucose but the glycosidic linkages differ The difference is based on two ring forms for glucose alpha a and beta b Know the general structures of the three types of lipids Fats Phospholipids and Steroids and be able to state what their main biological functions are Fats for energy storage phospholipids for building membranes steroids are signaling molecules hormones Fats Fats are constructed from two types of smaller molecules glycerol and fatty acids is a three carbon alcohol with a hydroxyl group attached to each carbon A fatty acid consists of a carboxyl group attached to a long carbon skeleton Glycerol One fatty acid is attached to each OH in glycerol with an ester bond another example of a condensation reaction fatty acids may be are saturated or unsaturated o consist of three fatty acids that are completely saturated Most Saturated fats animal fats are saturated These fats tend to stack together to form solids butter Can clog arteries cause cardiovascular disease fish The inflexibility of double bond prevents them from stacking Thus they are liquid at room temperature have one or more unsaturated fatty acid Prevalent in plants and o Unsaturated fats Phospholipids In a phospholipid two fatty acids and a phosphate group are attached to glycerol The fatty acid tails are hydrophobic but the phosphate group forms a hydrophilic head When phospholipids are added to water they self assemble into a bilayer with the hydrophobic tails pointing toward the interior This bilayer arrangement of phospholipids is the major component of all cell membranes and forms a barrier between the aqueous environment and the aqueous interior of our cells Steroids are lipids characterized by a carbon skeleton consisting of four fused rings Cholesterol It is a component in animal cell membranes and is the precursor to several steroid hormones implicated in cardiovascular disease is actually an important steroid Steroids Know that proteins are polymers of amino acids held together by peptide bonds that each kind of protein has a unique amino acid composition
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