Biology 110 Chemistry Review (Part II) Pitts
1. Name four types of macromolecules that are studied in Biology 110.
2. Name three elements that are present in all carbohydrates.
3. What is the ratio of carbon, hydrogen, and oxygen in carbohydrates?
4. Name three groups of carbohydrates based on the size of the molecules.
5. Name an example of a monosaccharide that contains six carbon atoms.
6. Name two major functions of monosaccharides in living cells.
7. Name an example of a disaccharide.
8. What is the ratio of carbon, hydrogen, and oxygen in a disaccharide?
9. Describe an example of a condensation reaction.
10. Describe an example of a dehydration reaction.
11. What is the primary function of disaccharides in living organisms?
12. Name three example of polysacccharides that are polymers of glucose.
13. What types of organisms produce starch?
14. What is the primary function of starch in plants?
15. What type of organisms produce glycogen?
16. What is the primary function of glycogen in animals?
17. What type of organism produces cellulose?
18. What is the function of cellulose in plants?
19. Why can humans not digest cellulose?
20. How does the ratio of C:H:O differ between carbohydrates and lipids?
21. Are lipids polarized or nonpolarized? What effect does this have on their interactions with water?
22. What letter of the alphabet does a fat molecule resemble?
23. How many carbon atoms are present in one molecule of glycerol?
24. How many fatty acids are present in one molecule of fat?
25. How many carbon atoms are present in a fatty acid?
26. What is a triglyceride?
27. Name three functions of fats in humans.
28. Why do hummingbirds store fat rather than carbohydrates as reserve energy supply before crossing the Gulf of Mexico?
29. Why are human (and rat) kidneys usually surrounded by fat?
30. How does a saturated fat differ from an unsaturated fat?
31. Which type of fat, saturated or unsaturated, is more likely to cause problems if eaten in large amounts by humans? Why?
32. What does the term “polyunsaturated” mean?
33. How does a phospholipid differ from a fat?
34. Name a cell part in which phospholipids are present.
35. What is a biological function of waxes?
36. Name three example of steroids.
37. How could you recognize a steroid if you saw a diagram of its molecular structure?
38. True or False: Cholesterol is harmful to the human body.
39. What molecule does the human body use as a starting point for the construction of sex hormones?
40. Are anabolic steroids really the “Drug of Champions”?
41. What are some beneficial effects of anabolic steroids on humans?
42. What are some harmful effects of anabolic steroids on humans?
43. What the “building blocks” of proteins?
44. How many different kinds of amino acids are used for the construction of proteins in plants? in animals? in bacteria?
45. How many amino acids are present in a protein?
46. How many different kinds of amino acids are present in a protein?
47. True or False: all enzymes are proteins.
48. True or False: all proteins are enzymes.
49. What is the function of a peptide bond?
50. How does a peptide bond form?
51. How many peptide bonds are present in a protein containing 13 amino acids?
52. How many amino acids are present in a protein containing 47 peptide bonds?
53. Why do dieticians refer to some, but not all, amino acids as “essential”?
54. What does the primary structure of a protein describe?
55. What does the secondary structure of a protein describe?
56. What does the tertiary structure of a protein describe?
57. What does the quaternary structure of a protein describe?
58. What is a disulfide bond?
59. What is the function of hydrogen bonds and disulfide bonds in maintaining protein structure?
60. What happens to a protein when it is denatured?
61. How can a protein be denatured?
62. Describe the quaternary structure of hemoglobin.
63. What is the function of hemoglobin in the human body?
64. In what type of human body cell is hemoglobin found?
65. What causes sickle cell anemia?
66. What are the effects of sickle cell anemia on humans?
67. Name the three components of a nucleotide.
68. Name three molecules that each contain only one nucleotide.
69. What molecule is represent by the abbreviation ATP? by ADP? by AMP?
70. True or False: plants can manufacture energy.
71. True or False: animals can manufacture energy.
72. True or False: some bacteria can manufacture energy.
73. True or False: since plants can undergo photosynthesis, plants do not respire.
74. Define: cellular respiration.
75. What is the primary product of cellular respiration in all organisms?
76. Why do living organisms produce ATP?
77. What components are necessary for the production of ATP?
78. What are the two major components of a chromosome? Which of these carries genetic information?
79. What are the building blocks of DNA? of RNA?
80. How many kinds of nucleotides are present in DNA?
81. How many kinds of nucleotides are present in RNA?
82. What nitrogen base may be present in DNA but not in RNA?
83. What nitrogen base may be present in RNA but not in DNA?
84. Compare the physical shape of a molecule of DNA with the shape of a molecule of RNA.
85. How does RNA differ from DNA?
86. What does the term deoxy- mean?
87. How does deoxyribose sugar differ from ribose sugar?
88. What is a gene?
89. What are the chemical components of a gene?
90. How many genes are present in a chromosome?
91. How is information stored in a DNA molecule?
92. How long is a gene?ANSWERS (Chemistry II review in Pitts' Biology 110)
1. carbohydrates, lipids, proteins, nucleic acids
2. carbon, hydrogen, oxygen
3. 1:2:1 This ratio does not have be exactly 1:2:1, especially in the larger molecules. Sucrose, for example, has 12 carbon atoms, 22 hydrogen atoms, and 11 oxygen atoms; this is close enough to satisfy the “approximate” 1:2:1 ratio requirement.
4. monosaccharides, disaccharides, polysaccharides
5. glucose, fructose
6. A. used as a structural material to build parts such as cell walls; B. broken down to provide energy
7. sucrose (more commonly called table sugar)
8. approximately 1:2:1 (refer to question and answer 3)
9-10. A condensation reaction results in the “condensing” or bringing together of two or more atoms or molecules into one molecule. Frequently, this results in the removal of one or more water molecules from the reactants. If water is removed from the reactants and water is one of the products, then the reaction is a dehydration. This process is frequently reversed: we may add water to a large molecule and break it down into smaller components; this would be an example of a hydration. The addition of glucose to fructose to produce sucrose and water is an example of a dehydration reaction.
11. Disaccharides serve primarily as transport molecules as in the sap of plants.
12. starch, glycogen, cellulose
A polymer is a long molecule that consists of a chain of smaller molecules (usually of one type, such as glucose in starch) bonded to each other. Each of the small units is called a monomer.
13. plants
14. Starch is used primarily as a storage molecule. Which is easier to control and protect?
(A) huge numbers of small molecules (such as glucose), or (B) a few large molecules (such as starch) [The answer is B.]
15. animals
16. Glycogen is a storage molecule in animals, in the same way that starch is a storage molecule in plants.
17. plants
18. Cellulose is a structural component of plant cell walls. In most plant cells, cellulose is the most abundant molecule present in cell walls. The cellulose molecules help strengthen the cell walls which, in turn, help support the plant.
19. Humans cannot digest cellulose because they cannot produce the enzyme cellulase. Our cells cannot manufacture the enzyme cellulase, which you recall is a protein, because we no not have the genetic instructions for building cellulase.
20. Carbohydrates have a C:H:O ration of approximately 1:2:1; lipids, which also consist primarily of carbon, hydrogen, and oxygen, may have a 1:2 carbon to hydrogen ratio, but the carbon to oxygen ratio will not be anywhere close to 1:1. For example, a molecule of beef fat contains 57 carbon atoms, 110 hydrogen atoms (which is close to a 1:2 carbon to hydrogen ratio) but only 6 oxygen atoms (which gives a 9:1 carbon to oxygen ratio instead of the approximate 1:1 carbon to oxygen ratio found in carbohydrates).
21. Lipids are typically not polarized. One of the consequences of this is that lipids and water do not readily mix: lipids are hydrophobic. As a result, many of the lipids (such as waxes) make good waterproofing compounds for biological structures such as leaves (and for non-biological structures such as automobiles.)
22. the capital letter “E”
23. three
24. A fat may contain either one, or two, or three fatty acids. The most abundant fats in humans contain three fatty acids.
25. The number of carbon atoms present in a fatty acid varies from a low of 14 to a high of 22. Different types of animals have different numbers of carbons in their fatty acids; this is one of the reasons that beef fat and pork fat do not taste the same to us.
26. The term triglyceride is the name of a common type of fat molecule that consists of one glycerol and three fatty acids.
27. Three function of fat in humans: A. reserve supply of energy; B. thermal insulation;
C. shock absorber.
28. A gram of fat can store two to six times the amount of energy that one gram of carbohydrate can store. About 1.5 to 2 grams of fat are needed to supply energy for the non-stop flight of a hummingbird's fall migration across the Gulf of Mexico. These 1.5 to 2 grams of fat significantly increase the body mass (which is normally about 3.5 grams) and the hummingbird is barely able to lift off on its flight. If the hummingbird stored an equal amount of energy in carbohydrates, at least 4 grams of carbohydrate would be needed, but the hummingbird would not be able to fly with this much additional weight.
29. The kidneys of mammals such as humans and rats are not protected by bones; the layers of fat around the kidneys protect the kidneys by absorbing and reducing the impact of physical blows.
30. A saturated fat contains only single covalent bonds while an unsaturated fat contains some double and/or triple covalent bonds. The term “saturated” is used here to indicate that no more hydrogen atoms can be added to the molecule (i.e., it is “full” of hydrogen). A double bond in a fat could be converted into a single bond and then two more hydrogen atoms could be added to the molecule to stabilize it. Therefore, a fat with double or triple bonds is not saturated (i.e., it is “not full”) with hydrogen.
31. The saturated fats (including most animal fats, such as hog fat which is processed into lard) are more likely than the unsaturated fats to cause problems in the human body. Specifically, people who eat a diet containing large amounts of saturated fat are more likely to have problems with their circulatory system because of the buildup of plaques that block the flow of blood in the vessels.
32. Polyunsaturated means that a molecule contains many (but without an exact number being specified) double and/or triple covalent bonds.
33. A phospholipid differs from a fat by having the third fatty acid replaced with phosphate (and an additional group that is usually polarized). This give a phospholipid the appearance of an “F” rather than an “E” and also changes some of its chemical properties (such as making at least the polarized part soluble in water).
34. Phospholipids are a major component of most cell membranes (and every cell has a cell membrane).
35. Waxes are not polarized and as a result do not readily mix with water (i.e., the waxes are hydrophobic); consequently, waxes are useful for waterproofing leaves and other structures.
36. cholesterol, estradiol, testosterone
37. Steroids typically contain four rings of carbon; each ring has either 5 or 6 carbon atoms.
38. This is one of the reasons that Pitts does not like true-false questions. As is true for water and many other biological molecules, if we do not have enough cholesterol or if we have too much cholesterol, problems will result. We must have cholesterol, for example for building cell membranes, and when it is present in “normal” (i.e., not excessively low or high amounts) it is not harmful. As stated, the question cannot be answered correctly; in order to answer correctly we would need to know something about the quantities of cholesterol involved.
39. cholesterol (Human cells can make all of the cholesterol that they need; some of this cholesterol is used as the starting point for the construction of other molecules, such as the sex hormones estradiol and testosterone.)
40. No. Anabolic steroids will stimulate muscle growth and development, but the harmful side effects may override any benefits.
41. Anabolic steroids, in small amounts, could be useful in people who cannot produce testosterone and, consequently, might have small, weak muscles. Medical supervision is essential for this application.
42. Anabolic steroids may damage the liver, kidneys, and other internal organs; they may cause cancer and they may cause sterility.
43. amino acids (Can you draw the structure and label the parts of an amino acid?)
44. Twenty. The same 20 kinds of amino acids are used by all living organisms to manufacture their proteins. Many additional kinds of amino acids can be synthesized in the laboratory, but these other types are not used in living organisms.
45. The actual number of amino acids in proteins varies tremendously, depending on the size of the protein. Some proteins will have only a few, perhaps 10 or 11, amino acids, while other proteins may contain thousands of amino acids. (This question is somewhat like asking, how many pages are in a book?)
46. Some proteins contain only one kind of amino acid. Other proteins may contain several, but not all 20, different kinds of amino acids. If the protein is very large, chances are it will contain many of the different kinds of amino acids. Like our use of the letters “a” and “e” versus the use of the letters “x” and “z” in our writing, some kinds of amino acids are used more frequently than are others.
47. True; the only enzymes we have considered in Biology 110 are composed of proteins.
48. False; proteins may serve as structural molecules for the building materials such as muscle and egg white; some proteins have other special functions. (see question 63)
49. A peptide bond is a covalent bond that “holds” one amino acid to another amino acid. The peptide bond forms between a nitrogen atom (in the amino group) of one amino acid and a carbon atom (in the carboxyl group) of a second amino acid. A peptide bond has no special properties; it is a typical covalent bond. However, we give it a distinguishing name because of its position and importance in connecting two amino acids.
50. A peptide bond forms when the amino group (NH2) of one amino acid loses a hydrogen atom; this results in the nitrogen atom becoming unstable (because its outer shell of electrons is no longer full). At the same time the carboxyl group (COOH) of another amino acid loses an OH group; this results in the carbon atom becoming unstable. The nitrogen atom and the carbon atom each need to gain one electron in order to become stable; they achieve stability by sharing a pair of electrons (which is the covalent peptide bond).
51. If 13 amino acids are arranged in a straight line (and this is normally the only arrangement), 12 peptide bonds would be present.
52. If 47 peptide bonds are present, the protein should have 48 amino acids. [Remember: number of amino acids - 1 = number of peptide bonds]
53. The term “essential amino acids” as used by a dietician refers to the eight amino acids that humans cannot manufacture. It is “essential” that these amino acids be present in our food, otherwise we will not be able to build all of the types of the proteins that we need.
54. Primary structure of a protein describes the name and position of each amino acid (i.e., the name of number 1 amino acid, the number 2 amino acid, the name of number 3 amino acid, etc.).
55. Secondary structure of a protein partially describes the shape of the molecule. Secondary structure describes the arrangement of the amino acid chain; two common arrangements are the helix (or spiral) and the pleated (or zig-zag) patterns.
56. Tertiary structure of a protein partially describes the shape of the molecule. Tertiary structure describes how the chain of amino acids folds and loops around and over itself. These patterns can be very complex, but the final shape is not randomly determined. Each protein has a specific tertiary structure that is determined by its primary and secondary structures. Recall that in enzymes the shape of the molecule determines whether or not the enzyme will be functional. If we change the shape of the active site of an enzyme (i.e., if we alter the tertiary structure), the enzyme will no longer be functional.
57. The quaternary structure of a protein describes the number of polypeptide chains that are present. Only one chain may be present, or the protein may contain several chains. (see question 62)
58. A disulfide bond is a covalent bond that forms between two sulfur atoms. Sulfur, like oxygen, has six electrons in its outer shell. In order to become stable, each sulfur needs to gain (or borrow) two more electrons. Imagine a chain of amino acids that has the shape of the letter “U”; if each of the amino acids at the top of the “U” contains sulfur, and if a disulfide bond forms between these two sulfur atoms, the chain will be held in the “U” shape.
59. Hydrogen bonds and disulfide bonds help hold the chain of amino acids in a specific shape; hence, these bonds are partially responsible for the secondary and tertiary structure of a protein.
60. Denaturing a protein results in a change in the shape of the molecule. Both secondary and tertiary structures may be changed.
61. Methods of denaturing a protein include the application of heat (as in cooking an egg), changing the pH, or mixing with alcohol.
62. Quaternary structure describes the number of polypeptide chains that are present. A molecule of hemoglobin contains four polypeptide chains. There are two kinds of polypeptide chains in hemoglobin; these are alpha chains and beta chains. A hemoglobin molecule contains two alpha chains and two beta chains. Each of these four chains contains about 150 amino acids, so the total number of amino acids in a hemoglobin molecule is approximately 600.
63. Hemoglobin is a protein whose primary function in the human body is to transport oxygen from the lungs to other parts of the body.
64. Hemoglobin is primarily found in red blood cells.
65-66. Sickle cell anemia (or the sickle cell trait) results from the substitution of one amino acid for another amino acid on each of the two beta chains of hemoglobin. The substitution of one amino acid in place of another amino acid in hemoglobin is somewhat like typing the letter “E” instead of the letter “I” when writing the word “bid.” The word “bed” has a totally different meaning than the word “bid,” even though both contain the same number of letters. As a result of the amino acid substitution in hemoglobin, the molecule has a different shape: its primary structure has altered its secondary and tertiary structure. The changed hemoglobin molecules (of which there may be millions in each red blood cell) cause the red blood cells to change shape and they are no longer able to squeeze through some small blood vessels. Blockage of blood vessels prevents some tissues from receiving oxygen and nutrients; these issues may die. If these tissues are in the brain, the person may die.
67. Three components of a nucleotide are: (1) nitrogen base (either adenine, guanine, thymine, cytosine, or uracil), (2) five carbon sugar (either ribose sugar or deoxyribose sugar), and
(3) one, two, or three phosphate groups.
68-69. Adenosine monophosphate (AMP); adenosine diphosphate (ADP); and adenosine triphosphate (ATP)
70-71-72. Each is false. No living organism or any biological process can manufacture energy. Living organisms may capture energy and store that energy in food (e.g., in photosynthesis); organisms may transfer energy from food to molecules of ATP (the process of cellular respiration); organisms may use energy from ATP to carry out cellular activities, but none of these activities involve the manufacturing or destruction of energy.
73. False. The process of photosynthesis results in the capture of light energy, the conversion of this light energy into chemical energy, and the storage of this chemical energy in molecules of food. While food molecules (such as glucose) do contain much energy, food molecules cannot directly supply this energy to cellular activities. (Remember the student with the one hundred dollar bill in front of the snack machine?) Energy from the food must be transferred into ATP (by the process of cellular respiration); cells can use ATP as an energy source. So, even though plants can carry out photosynthesis and store energy in food, plants must transfer this energy into ATP (i.e., carry out cellular respiration) like all other living organisms.
74. Cellular respiration is a complex series of chemical reactions that results in the transfer of energy from food molecules into molecules of adenosine triphosphate (ATP). [notes: (1) The breakdown of ATP releases energy which is then available for cellular activities that require energy. (2) Cellular respiration does not manufacture energy. (3) Cellular respiration and breathing are two totally different processes. (4) Two major types of cellular respiration (aerobic respiration, which involves the use of environmental oxygen; and anaerobic respiration, which does not require environmental oxygen) will be described later in the course.]
75. Molecules of the high energy compound adenosine triphosphate (ATP) are the products of all types of cellular respiration in all living organisms. Not all organisms use exactly the same reactions to produce ATP (How many different ways are there for traveling from Martin to Memphis?), but the end product is the same: ATP.
76. Organisms produce adenosine triphosphate (ATP) in order to have energy available for cellular activities. Most cellular activities are coupled to (i.e., depend on) the breakdown of ATP.
77. Adenosine triphosphate (ATP) is typically manufactured by adding a phosphate group onto a molecule of adenosine diphosphate (ADP); energy must be available, as well as the appropriate enzyme, for this reaction to occur.
78. Chromosomes consist primarily of molecules of deoxyribonucleic acid (DNA) and proteins. Contrary to earlier beliefs, we now know that genetic information is contained in DNA.
79. The building blocks of DNA (deoxyribonucleic acid) and RNA (ribonucleic acid) are nucleotides.
80. Molecules of DNA consist of four different kinds of nucleotides.
81. Molecules of RNA consist of four different kinds of nucleotides.
82. The nitrogen base thymine is present in some of the nucleotides of DNA, but thymine is not present in any of the nucleotides of RNA.
83. The nitrogen base uracil is present in some of the nucleotides of RNA but uracil is not present in any of the nucleotides of DNA.
84. Molecules of DNA are commonly described as “ladder-like” because of the two parallel chains of molecules that are connected by the “steps” or “rungs” of nitrogen bases. Molecules of RNA resemble “half of a ladder that has been divided lengthwise.” Both molecules are long and twisted.
85. Molecules of RNA differ from molecules of DNA in several ways: (1) RNA, but not DNA, has some nucleotides containing the nitrogen base uracil; (2) RNA nucleotides contain ribose sugar, while DNA nucleotides contain deoxyribose sugar; (3) RNA molecules consist of a single chain of nucleotides (i.e., “half of a ladder”) while DNA consists of a double chain of nucleotides (i.e., “a ladder”).
86-87. The term deoxy- means “less oxygen.” This term is used to describe the five carbon sugar molecules (deoxyribose sugar) of DNA which contain one less oxygen atom than do the five carbon sugar molecules (ribose sugar) of RNA. The difference of only one oxygen atom between these two sugar molecules results not only in a difference in the names of the molecules but also in differences in the chemical properties of the two molecules.
88. A gene: (1) is a section of a chromosome; (2) is composed of DNA and protein;
(3) contains information for the manufacturing of one protein (i.e., determining the primary structure (see question 54) of a protein.)
89. A gene is composed of DNA and protein.
90. A chromosome may contain only a few genes or several thousand genes. Asking how many genes are present in a chromosome is like asking how many pages are present in a book. Which book? Which chromosome? The answer depends on the specific chromosome that we select for study.
91. Information is stored in molecules of deoxyribonucleic acid (DNA) by arranging the four different kinds of nucleotides (the “building blocks” of DNA) in a specific sequence or order. This is exactly the same thing we do when we spell a word: we arrange the letters in a specific sequence that has meaning to us and conveys this information the reader. While our English language has an alphabet of 26 letters from which we can select when spelling words, the “alphabet” of DNA consist on only four different kinds of nucleotides [recall nucleotides containing (1) adenine, (2) thymine, (3) cytosine, and (4) guanine?]. Even though an alphabet of only four “letters” (i.e., nucleotides) might seem to be limited in the amount of information it can express, this is not true. These four nucleotides can be combined in an almost infinite number of ways; remember that the “words” (i.e., genes) of DNA may consist of dozens, hundred, or even thousands of “letters” (i.e., nucleotides).
92. The length of genes (that is, the number of nucleotides present) is variable. Some genes are short, consisting of a small number of nucleotides; such a gene contains information for construction of a small protein molecule. Other genes may be very long, in some cases containing thousands of nucleotides; these genes contain information for building large protein molecules.
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