Bio 12 Chapter 2 Test Review 1.Know the difference between ionic and covalent bonds In order to complete outer shells in electrons bonds can be Ionic; one atom donates or receives electrons Covalent; atoms share electrons 2. Know what a polar covalent bond is: bond that has UNEQUAL sharing of electrons 3. Be able to explain why water is a polar molecule *Polar bonds have charges on either end and often attract to each other *Atoms ‘hogging’ the electrons have an electronegative charge, and atoms ‘lacking’ electrons have an electropositive charge 4. Explain what a hydrogen bond is and why it is important Electronegative atoms on one molecule are attracted to electropositive atoms on a different molecule. Form Hydrogen bonds. 5. Explain the unique characteristics of water and explain how they are useful to organisms (poster you made) *Water molecules are attracted to other polar molecules cohesion – when one water molecule is attracted to another water molecule adhesion – when polar molecules other than water stick to a water molecule (Steady column of water) *Water warms up and cools down slowly (high heat capacity) *Water has a high heat of vaporization because so many hydrogen bonds must be broken for water to evaporate *A solution consists of a solute dissolved into a solvent *Water’s hydrogen bonds help it dissolve other polar molecules *Frozen Water is Less Dense than Liquid Water and floats on liquid water 6. Explain the difference between an acid and a base and what pH is. pH is the Measurement of Acidity (acid) or Alkalinity (base) of a Solution. The pH scale goes from 0 to 14 - pH 0 is acidic - pH 7 is neutral - pH 14 is basic The greater the H+ concentration, the lower the pH The lower the hydrogen ion concentration, the higher the pH 7. Define buffer and explain its role in biological systems Buffers Help Keep the pH of Body Fluids Relatively Constant Buffer System: the combination of a weak acid and the base that forms when the acid dissolves in water By binding or releasing H+’s, it maintains a constant concentration of free H+’s in the solution 8. Explain how differences in carbon skeleton and attached functional groups cause organic molecules to have different chemical properties A hydrocarbon chain can turn back on itself to form a ring compound, or a spiral or a series of folds due to the interaction between the atoms and the functional groups. Functional groups are specific combinations of bonded atoms that always react in the same way. 9. Explain the difference between hydrophobic and hydrophilic • Hydrophilic (water-loving) molecules form hydrogen bonds with water • Hydrophobic (water-fearing) molecules do not form hydrogen bonds with water 10. Differentiate between the four classes of macromolecules and be able to identify them from a picture of their structure 1) Carbohydrates monomer polymer (Chitin) 2) Proteins 3) Lipids Which Is a Source of Unsaturated Fatty Acids? Linseed Oil Beef Fat Est 4) Nucleic Acids-formed with ribose sugar, phosphate and nitrogenous base P P P P 11. Explain the relationship between monomers and polymers of the macromolecules (glucose vs starch, amino acids and proteins…) Monomer or building blocks polymer glucose Starch, cellulose or glycogen, chitin Amino acid proteins Glycerol and fatty acids Lipids (also Steroids, Waxes) Nucleotides (sugar, phosphate group and DNA, RNA, ATP nitrogenous base) 12. Differentiate between dehydration synthesis and hydrolysis and make sure to understand whether water is added or removed and whether energy is released or required in the reaction By taking out a water molecule (hydroxyl-OH from one and Hydrogen-H from another monomer) between building blocks, you can link monomers or building blocks to make a larger molecule (polymer). This is called dehydration synthesis.Energy is required (endergonic) By adding a water molecule, you can cut the larger polymer into its individual monomers or building block components. This is called hydrolysis (water cutting). Energy is given off (exergonic) 13. Know the difference between glycogen and cellulose Glucose converts to a long-chain carbohydrate, Glycogen, to store in the liver, in animals. Glucose converts into a long-chain carbohydrate, cellulose, to store in the cell walls of plants that give it structural support. 14. Explain why fats and oils are insoluble in water Both fats and oils are hydrophobic. That is, they do not attract water since there is no – or + end. They are non-polar. 15. What is the difference between saturated and unsaturated fatty acids? Saturated fats contain no double bonds between the carbons in the chain of the fatty acid. Unsaturated fats contain double bonds between the carbons. They are fluid as a result of the space created between the chains due to the kinks where the double bonds are. 16. Distinguish between phospholipids and triglycerides Triglycerides have a glycerol backbone and three fatty acid chains attached (FAT) Phospholipids have a glycerol backbone and TWO fatty acid chains and a phosphate group 17. What are waxes? What are steroids? Waxes: lipids that protect from water (plants, ears)and energy storage in plankton; long chain fatty acid attached to an alcohol, solid at room temperature Steroids: lipids that are fused carbon rings that can be hormones (chemical messengers in the body) or structural units (cholesterol is a part of the cell membrane) 18. Be able to draw and label the parts of the phospholipid bilayer Lipids: Structure • Phospholipid—component of cell membranes Polar Head Glycerol Fatty Acid Tails Hydrophilic Hydrophobic 19. Know the different tests one can use to determine if there is a presence of proteins, simple sugars or complex sugars (LAB) + for Simple sugars (like glucose): benedict’s solution (turns from peacock blue to orange or brick red) + for Complex sugars (like starch): Lugol’s IODINE (orange) turns the substance black + for Proteins (like meat): Biuret’s solution turns violet 20. Give three examples of proteins composed of amino acids and describe the function of each. Keratin-structural support in nails Muscle (actin and myosin) for movement Collagen-maintains the elasticity of skin Hemoglobin-a protein in red blood cells that carries oxygen to tissues Do these questions: Multiple choice questions #1-39 just the number and letter answer (do corrections afterwards in a different colour and explain the correction) Short Answer questions: #43, 44, 46, 47, 49, 51-54, 55-57, 59, 60, 62, 63, 68, 72, 77, 79, 81 (do corrections afterwards in a different colour and explain the correction) Note: #19, insulin is a protein and therefore has amino groups with N Short Answer questions 43) The strong acid hydrogen chloride can be dissolved in water. The pH will decrease and cause the solution to be more acidic due to the release of hydrogen ions. 44) Bond X is a hydrogen bond. 46) Functions: acts as a solvent by dissolving substances, acts as a lubricant by lubricating joints, acts as a temperature regulator for body heat. 47) The electronegativity of the covalent bond causes the shared electron pair to spend more time around the nucleus of the oxygen atom than that of the hydrogen atom in a water molecule. This creates a slightly negative charge on the oxygen atom and slightly positive charges on the hydrogen atoms resulting in an unequal sharing of electrons and a polar covalent bond. 49) Runners eat meals with large quantities of carbohydrates a few days before a marathon because it provides quick fuel and short-term energy storage. The body will store the carbohydrates needed for the race and on the day of the race, glycogen will be converted into glucose so that glucose can be used to produce ATP during cellular respiration. 51) Dehydration synthesis is illustrated in the diagram. It shows the removal of a hydroxyl group of one amino acid and the hydrogen atom of the second amino acid, the equivalent of water, to allow the combining of the two into a dipeptide. 52) Bond X is a peptide bond. 53) A dipeptide and a water molecule will form as a result of this reaction. 54) 9 molecules of water will be produced if 10 amino acids are linked 55) Lactose is classified as a disaccharide that belongs to the carbohydrate family. 56) Water is required. 57) Hydrolysis is illustrated in the diagram. 59) a. The base sequences of specific sections of DNA contain a code that specifies the sequence of amino acids in the proteins of the cell. b. Nucleic acids are polymers of nucleotide monomers. c. A monosaccharide only has one sugar molecule whereas a polysaccharide contains many sugar molecules. d. A polypeptide is made up of amino acids joined together by peptide bonds. e. In the secondary structure of a protein, hydrogen bonding between the amino acids causes the polypeptide to form an alpha helix or a beta pleated sheet. f. The polarity in water molecules allows it stick together or cohesion to occur. Unequal sharing of electrons in water. 60) a. A glycerol has three carbon atoms, each of which has a hydroxyl (-OH) group bound to it. b. A triglyceride has three fatty acids attached to glycerol whereas a phospholipid has a phosphate group that replaces one of the fatty acids. c. A peptide bond forms between carboxyl group and the nitrogen of the amino group in a dipeptide. A hydrogen bond forms between different amino acids in the polypeptide chain. d. An unsaturated fatty acid has a double bond meaning it has one less hydrogen atom than a saturated fatty acid. 62) The positive result of both the disaccharide maltose and the monosaccharide glucose means there is a presence of sugar.