Protein Unit Study Guide/Review Sheets You should begin studying now for your test on Thursday! If you have questions, make sure to ask them. Stop in before or after school. Review questions: 1. What elements comprise proteins? C, H, O, N 2. Are proteins organic? YES – CONTAIN CARBON AND HYDROGEN, THE REQUIREMENT FOR BEING AN ORGANIC MOLECULE 3. What element MAY be present in proteins? SULFUR 4. What is the name of the monomer of proteins? AMINO ACID 5. What type of bond links amino acids together? PEPTIDE BONDS 6. What functional groups are shared between ALL amino acids? (giving it its name): AMINO GROUP (NH2) and CARBOXYL/CARBOXYLIC ACID/ACID GROUP (COOH) 7. What group on an amino acid differentiates it from, for example, a carbohydrate? AMINO GROUP (NH2) BECAUSE CARBOHYDRATES DO NOT CONTAIN NITROGEN 8. Is the group from question #7 the same or different on each amino acid? THE SAME – ALL AMINO ACIDS HAVE AN AMINO GROUP 9. What group on an amino acids differentiates it from the next amino acid? THE R GROUP ALSO CALLED THE VARIABLE GROUP; ON EACH AMINO ACID THE R GROUP IS DIFFERENT 10. How many standard amino acids are there? 20 11. How many (of the standard amino acids) can our bodies synthesize? 11 12. What are the amino acids that our body can synthesize named? NONESSENTIAL 13. How many (of the standard amino acids) can’t our bodies synthesize? 9 14. What are the amino acids that our body can’t synthesize named? ESSENTIAL 15. If our bodies can’t synthesize certain amino acids, where do we get them from? OUR DIET (FOOD) 16. Why is it important that we have all of the twenty amino acids? IF YOU DID NOT HAVE ALL THE BUILDING BLOCKS NEEDED TO MAKE PROTEINS YOU WOULDN’T BE ABLE TO MAKE CERTAIN PROTEINS; FOR EXAMPLE, IF YOU DIDN’T HAVE AMINO ACID #6, YOU COULDN’T MAKE ANY OF THE PROTEINS THAT CONTAIN AMINO ACID #6 17. What neutral molecule is formed when amino acids bonds together? WATER 18. What is the name of a molecule that has two amino acids linked together? DIPEPTIDE 19. What are the names of a molecule that has 100 amino acids linked together (two answers)? POLYPEPTIDE, PROTEIN 20. Explain how three different proteins can be composed of 50 amino acids. THERE ARE A COUPLE WAYS: SAME AMINO ACIDS, 3 DIFFERENT ORDERS DIFFERENT AMINO ACIDS 21. List the names of the qualitative tests and what they test for: Ninhydrin Biuret Lead Acetate Sakaguchi’s Xanthroproteic Ammonia (NH3) or PEPTIDE BONDS Sulfur groups Guanidines Phenyl Primary Amine (NH2) or (N-C-N) groups/substituted 5 or 2 or more aromatic RINGS N Secondary Amine amides (N-C=O) (NH) 1 22. Define the primary structure: THE SEQUENCE OF AMINO ACIDS 23. Describe the type of bonding in secondary structure and where it occurs: HYDROGEN BONDING WITHIN THE POLYPEPTIDE BACKBONE 24. Two types of secondary structure: ALPHA HELIX (“TWISTED”) AND BETA SHEET (FLAT AND FOLDED “ACCORDIAN”) 25. Four chemical interaction that occur in tertiary structure: SALT BRIDGES (ACID-BASE, IONIC BONDS); DISULFIDE BONDS (S-S); HYDROGEN BONDING (EXAMPLE: NH-O; MUST HAVE TWO ELECTRONEGATIVE ATOMS); AND NON POLAR HYDROPHOBIC (WATER FEARING, TWISTS AWAY FROM WATER) 26. Two types quaternary structure: FIBROUS (LONG, STRINGY); AND GLOBULAR (LIKE A BLOB) 27. Compare tertiary and quaternary structure: TERTIARY STRUCTURE INVOVLES ONLY ONE POLYPEPTIDE CHAIN; QUATERNARY STRUCTURE IS WHEN TWO POLYPEPTIDE CHAINS INTERACT 28. What makes a protein complete? A PROTEIN IS COMPLETE IF IT CONTAINS ALL OF THE ESSENTIAL AMINO ACIDS 29. What are food sources of complete proteins? ANIMAL PRODUCTS; MEAT, MILK 30. What makes a protein incomplete? A PROTEIN IS INCOMPLETE IF IT DOES NOT CONTAIN ALL OF THE ESSENTIAL AMINO ACIDS 31. List food sources of incomplete proteins. VEGETABLES 32. What is the relationship between structure and function? STRUCTURE DETERMINES FUNCTION 33. Can proteins provide energy? YES, 4 KCALS/GRAM 34. Explain why proteins are generally not used as a source of energy. PROTEINS HAVE SO MANY VARIOUS VITAL ROLES THAT IT IS NOT FAVORABLE TO USE THEM FOR ENERGY 35. How do proteins protect you from illness? SOME PROTEINS FUNCTION AS ANTIBODIES, WHICH “MARK” FOREIGN INVADERS (BACTERIA, VIRUSES) FOR DESTRUCTION 36. How are proteins involved in letting your body know what to do and when to do it? SOME PROTEINS ARE HORMONES; HORMONES SIGNAL ANOTHER PART OF YOUR BODY TO DO SOMETHING, MAKE SOMETHING, ETC. 37. How are proteins involved in, for example, getting oxygen to your cells? SOME PROTEINS FUCTION AS TRANSPORTERS AROUND YOUR BODY (LIKE HEMOGLOBIN DELIVERING OXYGEN TO YOUR CELLS); SOME PROTEINS FUNCTION AS TRANSPORTERS FROM THE OUTSIDE OF A CELL OR MEMBRANE TO THE INSIDE OF A CELL OR MEMBRANE (LIKE ATP SYNTHASE LETTING H+ IONS THROUGH THE MEMBRANE DURING CHEMIOSMOSIS) 38. How are proteins involved in the acid-base balance of your body? SOME PROTEINS ACT AS BUFFERS; HELP BODY RESIST CHANGE IN PHIF TOO ACIDIC, “TAKE UP” H+; IF TOO BASIC, RELEASE H+ 39. How are proteins involved in the fluid balance of your body? VERY SIMPLY, BECAUSE OF THE PRESENCE OF CERTAIN PROTEINS IN THE BLOOD, FLUID MOVES BACK FROM TISSUES INTO THE BLOODSTREAM; WITHOUT THESE PROTEINS, FLUID BUILDS UP INSIDE TISSUES, AND THE TISSUE SWELLS 40. What structural role do proteins fulfill? PROTEINS FORM HAIR, NAILS, MUSCLES, TENDONS AND LIGAMENTS 41. FIBROUS: LONG, THIN, ABLE TO CONTRACT MUSCLE; GLOBULAR: MOVE THROUGH BLOODSTREAM, CARRY THINGSHEMOGLOBIN (GLOBULAR) 2 42. Define enzyme. SPECIALIZED PROTEINS THAT CATALYZE BIOCHEMICAL REACTIONS 43. Define activation energy. THE AMOUNT OF ENERGY NEEDED FOR A CHEMICAL REACTION TO OCCUR. 44. Describe specifically how enzymes speed up chemical reactions that otherwise would not occur. ENZYMES LOWER THE ACTIVATION ENERGY, SO IT IS REACHED QUICKER, AND THE REACTION CONCEQUENTLY HAPPENS FASTER 45. Why is an enzyme’s shape so important? Explain the “lock and key” model. EACH ENZYME ONLY CATALYZES ONE SPECIFIC REACTION; FOR EXAMPLE CATALASE ONLY CATALYZES THE REACTION H202 H2O + O2; THE STRUCTURE OF THE ENZYME, CATALASE, MUST FIT THE STRUCTURE OF THE SUBSTRATE, H2O2, PERFECTLY OR THE REACTION CANNOT BE CATALYZED AND WILL NOT HAPPEN; THIS “FITTING” IS REFERRED TO AS THE LOCK AND KEY (ENZYMESUBSTRATE COMPLEX) 46. Are enzymes reusable? YES 47. Why must enzymes be reusable? SINCE THEY ARE REQUIRED FOR ALMOST EVERY BIOCHEMICAL REACTION IN LIVING ORGANISMS, IT WOULD SIMPLY IMPOSSIBLE TO POWER THE PRODUCTION OF A NEW ENZYME EVERY TIME IT IS NEEDED ***ENZYMES ARE REUSABLE BECAUSE LIVING ORGANISMS SIMPLY COULD NOT MAKE ENOUGH ENZYMES TO CATALYZE REACTIONS IF THEY ONE USE ONLY; SINCE THEY ARE REUSUABLE, IT IS INHERANT THAT THEY ARE NOT USED UP IN CHEMICAL REACTION; IF THEY WERE USED UP, THEY COULDN’T BE REUSED!! 48. Are enzymes a reactant, product, or neither of a chemical reaction? NEITHER. THEY ARE NOT PART OF THE CHEMICAL REACTION, THEY JUST MAKE THE CHEMICAL REACTION HAPPEN FASTER 49. Label this chemical equation with the words reactant(s), product(s), and substrate(s) A+B+C+DE+F A,B,C,D ARE REACTANTS; THEY ARE ALSO THE SUBSTRATES, WHAT ENZYMES ACT UPON; E AND F ARE PRODUCTS; THEY ARE PRODUCED DURING THIS CHEMICAL REACTION; THE POINT OF THE ARROW IS ALWAYS POINTING TOWARDS THE PRODUCTS, ILLUSTRATING THE REACTANTS ARE CHANGED INTO PRODUCTS 50. Explain what this graph is demonstrating: THE RATE OF REACTION INCREASES AS SUBSTRATE CONCENTRATION INCREASES, THEN LEVELS OFF 51. Explain what this graph is demonstrating: THE RATE OF REACTION INCREASES AS ENZYME CONCENTRATION INCREASES, THEN LEVELS OFF 52. What will happen to the rate of an enzyme reaction as the concentration of substrate is increased from zero? E. IT WILL INCREASE, THEN LEVEL OFF (REFER TO GRAPH FROM #50) 53. Explain what happens to this enzyme’s activity at 55 degrees AND WHY: THE ENZYME STOPS WORKING BECAUSE IT IS TOO FAR AWAY FROM ITS OPTIMUM TEMPERATURE OF 40; IT MAY BE DENATURED, WHICH MEANS ITS SHAPE HAS BEEN CHANGED; SINCE ENZYME FUNCTION DEPENDS SO MUCH ON SHAPE, IF ITS SHAPE IS CHANGED, IT CAN’T FUNCTION (SEE QUESTION #45) 54. What will happen to the rate of an enzyme reaction as it is heated from very cold (near freezing) to very hot (near boiling)? B. IT WILL INCREASE, THEN DECREASE (REFER TO GRAPH FROM #53) 55. At which pH do enzymes function best? E. THE OPTIMAL PH DEPENDS ON THE PARTICULAR ENZYME. 3 56. Catalase catalyzes the conversion of H2O2 to 2H2O + O2. When you did this experiment, how could you tell that a reaction was occurring? BUBBLES SIGNALED THAT PRODUCTS WERE BEING FORMED (OXYGEN) 57. What is/are the substrate(s) in the reaction from #44? HYDROGEN PEROXIDE H2O2 58. What is/are the product(s) in the reaction from #44? OXYGEN AND WATER 59. What is the purpose of this enzyme in living tissue? TO BREAK DOWN POISONOUS H202 TO HARMLESS WATER AND OXYGEN 60. THEY DECREASE REACTION RATE; THEY MAY COMPLETELY STOP THE REACTION (IN EXTREME PH OR BOILING); THIS IS A RESULT OF THE ENVIRONMENT CHANGING THE STRUCTURE OF THE ENZYME BY “MESSING” WITH THE CHEMICAL INTERACTIONS (SALT BRIDGES, DISULFIDE BONDS, ETC) THAT HOLD IT TOGETHER 4