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
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or
2 or more
aromatic RINGS
N
Secondary Amine
amides (N-C=O)
(NH)
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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 PHIF 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 THINGSHEMOGLOBIN (GLOBULAR)
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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+DE+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.
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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
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