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Topic 25 Topic 25 Topic 25: Biochemistry Table of Contents Topic 25 Topic 25 Basic Concepts Additional Concepts.

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Presentation on theme: "Topic 25 Topic 25 Topic 25: Biochemistry Table of Contents Topic 25 Topic 25 Basic Concepts Additional Concepts."— Presentation transcript:

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2 Topic 25 Topic 25

3 Topic 25: Biochemistry Table of Contents Topic 25 Topic 25 Basic Concepts Additional Concepts

4 Many of the most important molecules in your body are polymers. Molecules of Life Biochemistry: Basic Concepts Proteins, carbohydrates, and nucleic acids, all extremely large molecules, are formed from small monomer subunits. Although lipids are usually not considered to be polymers, they, too, are formed from smaller molecules that have been linked together. Topic 25 Topic 25

5 You need relatively large amounts of proteins, carbohydrates, and lipids in your diet. Molecules of Life Biochemistry: Basic Concepts Complex reactions in your cells use some of these molecules and a few others to make a fourth group of biomolecules, the nucleic acids. Topic 25 Topic 25

6 The study of the chemistry of living things is called biochemistry. Biochemistry Biochemistry: Basic Concepts This science explores the substances involved in life processes and the reactions they undergo. Other than water, which can account for 80 percent or more of the weight of an organism, most of the molecules of life the biomoleculesare organic. Topic 25 Topic 25

7 The elemental composition of living things is different from the relative abundance of elements in Earths crust. Biochemistry Biochemistry: Basic Concepts Oxygen, silicon, aluminum, and iron are the most abundant atoms in Earths crust. Topic 25 Topic 25

8 Biochemistry Biochemistry: Basic Concepts All four of these elements can form the strong covalent bonds found in organic molecules. Topic 25 Topic 25 However, more than 95 percent of the atoms in your body are hydrogen, oxygen, carbon, and nitrogen.

9 Biochemistry Biochemistry: Basic Concepts Topic 25 Topic 25 Along with two other elements, sulfur and phosphorus, they are the only elements needed to make most of the proteins, carbohydrates, lipids, and nucleic acids found in every cell.

10 A protein is an organic polymer composed of amino acids bonded together in one or more chains. Proteins Biochemistry: Basic Concepts An amino acid has a central carbon atom, to which are bonded a carboxyl group, an amino group, a hydrogen atom, and a variable side chain designated as R, as shown in the following structural formula. Topic 25 Topic 25

11 Structure of an Amino Acid Biochemistry: Basic Concepts Topic 25 Topic 25

12 Amino acids bond to each other by forming a peptide bond, an amide group formed by a condensation reaction between the carboxyl group of one amino acid and the amino group of another. Structure of an Amino Acid Biochemistry: Basic Concepts Topic 25 Topic 25

13 Structure of an Amino Acid Biochemistry: Basic Concepts Two amino acids linked by a peptide bond form a dipeptide. Topic 25 Topic 25

14 A chain of two or more amino acids linked by peptide bonds is called a peptide. Structure of an Amino Acid Biochemistry: Basic Concepts The term polypeptide is applied to a chain of ten or more amino acids. Proteins may have one or several polypeptide chains, and each chain must have an exact sequence of amino acids. Topic 25 Topic 25

15 Proteins can fold into either round, globular structures or long, fibrous structures. Structure of an Amino Acid Biochemistry: Basic Concepts Topic 25 Topic 25

16 Structure of an Amino Acid Biochemistry: Basic Concepts Topic 25 Topic 25 The amino acid chains are held in place in three-dimensional structures by attractive forces between the side chains of different amino acids, which have been brought close together by the bending and folding of the polypeptide chains.

17 Many of the proteins in an organism act as enzymes. These proteins catalyze chemical reactionsspeeding up reactions or allowing the reactions to take place at a low temperature. Enzymes Biochemistry: Basic Concepts Topic 25 Topic 25

18 The reactants in an enzyme-catalyzed process are called substrates. The substrate(s) bind to the enzyme at a location called the enzymes active site, forming an enzyme-substrate complex. Enzymes Biochemistry: Basic Concepts This interaction enables the substrate(s) to react with a much lower activation energy than they would without an enzyme. Topic 25 Topic 25

19 Enzymes Biochemistry: Basic Concepts Topic 25 Topic 25 Click box to view movie clip.

20 Substrates are brought close together in the active sites of an enzyme, which lowers the activation energy of the reaction by facilitating the bonding together of the substrates to form a product. Enzyme Action Biochemistry: Basic Concepts Topic 25 Topic 25

21 Enzyme Action Biochemistry: Basic Concepts After the substrates have reacted, the product is released. The enzyme is then able to bind more substrate molecules and continue catalyzing the reaction. Topic 25 Topic 25

22 Familiar carbohydrates include sugars, starches, and cellulose. Carbohydrates Biochemistry: Basic Concepts Simple carbohydrates consist of a chain of carbon atoms having hydroxyl (–OH) groups and a carbonyl group, often in the form of an aldehyde group. Topic 25 Topic 25

23 The simplest carbohydrates are the simple sugars, or monosaccharides, which commonly have five or six carbon atoms. Monosaccharides Biochemistry: Basic Concepts Glucose, the main ingredient in corn syrup, is a familiar monosaccharide. Topic 25 Topic 25

24 Glucose has the molecular formula C 6 H 12 O 6 and can be represented by the following structures. Monosaccharides Biochemistry: Basic Concepts Topic 25 Topic 25

25 The most common simple sugars are glucose, fructose, and ribose. Monosaccharides Biochemistry: Basic Concepts Topic 25 Topic 25

26 A polymer of many monosaccharides bonded into a chain is called a polysaccharide. Polysaccharides Biochemistry: Basic Concepts Starch is a polysaccharide that consists only of glucose units. Topic 25 Topic 25

27 Polysaccharides Biochemistry: Basic Concepts Topic 25 Topic 25 Plants also link glucose units together in a different way to form the polysaccharide cellulose, which forms plant cell walls.

28 Animals store glucose as a polysaccharide called glycogen, which is similar to starch. Polysaccharides Biochemistry: Basic Concepts Topic 25 Topic 25

29 Lipids are the nonpolar substancesfats, waxes, and oilsproduced by living things. Lipids Biochemistry: Basic Concepts Lipids are not polymers, and their chemical structures vary widely. Topic 25 Topic 25 Click box to view movie clip.

30 The most familiar lipids are the plant oils and animal fats. Fatty Acids Biochemistry: Basic Concepts These lipids are esters of fatty acids, which are carboxylic acids with long, straight hydrocarbon chains usually having between 12 and 24 carbon atoms. Topic 25 Topic 25

31 The simplest fatty acids are the saturated fatty acids, which have no double bonds between carbon atoms. Saturated Fatty Acid Biochemistry: Basic Concepts Stearic acid is found in pork and beef tissue. Topic 25 Topic 25

32 Many other fatty acids have one or more double bonds between carbon atoms and, as a result, are unsaturated fatty acids. Monounsaturated Fatty Acid Biochemistry: Basic Concepts Oleic acid is a major component of olive oil. Topic 25 Topic 25

33 Animal fats and plant oils are made up primarily of triglycerides, molecules in which three fatty acids are bonded to a glycerol molecule by ester linkages, as shown in the following diagram. Triglycerides Biochemistry: Basic Concepts Topic 25 Topic 25

34 Phospholipids are triglycerides in which a polar phosphate group, instead of a third fatty acid, is bonded to the glycerol. Triglycerides Biochemistry: Basic Concepts Cell membranes consist of a double layer of phospholipid molecules. Topic 25 Topic 25

35 The membranes of living cells are formed by a double layer of lipids called a bilayer. Triglycerides Biochemistry: Basic Concepts Topic 25 Topic 25

36 Another class of lipids, steroids, consists of compounds whose basic structure is very different from those of other lipids, as shown below. Other Lipids Biochemistry: Basic Concepts Cholesterol, vitamin D, and some hormones are steroids. Topic 25 Topic 25

37 Lipids have two major biochemical roles in the body. The Functions of Lipids Biochemistry: Basic Concepts When an organism takes in and processes more food than it needs, excess energy is produced. The organism stores this excess energy for future use by using it to bond atoms together in lipid molecules. Topic 25 Topic 25

38 Later, when energy is needed, enzymes break these same bonds, releasing the energy used to form them. The Functions of Lipids Biochemistry: Basic Concepts You have learned that carbohydrates also store energy; however, the process is not as efficient as in lipids. Therefore, long-term storage of energy is usually in the form of lipids. Topic 25 Topic 25

39 The sequence of amino acids in a protein is determined by the genetic information coded into long-chain polymers called nucleic acids. Nucleic Acids Biochemistry: Basic Concepts The monomers that make up nucleic acids are called nucleotides. Topic 25 Topic 25

40 Each nucleotide is made up of three parts: a phosphate group, a five-carbon sugar, and a nitrogen-containing cyclic compound called a nitrogen base. Nucleic Acids Biochemistry: Basic Concepts The structure of a nucleotide is shown. Topic 25 Topic 25

41 Nucleic Acids Biochemistry: Basic Concepts Topic 25 Topic 25

42 Nucleic Acids Biochemistry: Basic Concepts Topic 25 Topic 25

43 The common nucleic acids are DNA (deoxyribonucleic acid) and RNA (ribonucleic acid). Nucleic Acids Biochemistry: Basic Concepts These names reflect the fact that DNA contains the sugar deoxyribose and RNA contains the sugar ribose. DNA exists as a pair of polymer chains in which the backbone of each chain consists of alternating phosphate and deoxyribose units. The bases stick out from the backbone. Topic 25 Topic 25

44 This model of a portion of a DNA molecule clearly shows its complexity. The Structure of DNA Biochemistry: Basic Concepts A single DNA molecule contains many thousands of nucleotides. Topic 25 Topic 25

45 The two chains of DNA are held together because the nitrogen bases of one chain are hydrogen-bonded to the nitrogen bases of the other chain. Base Pairing Biochemistry: Basic Concepts Because of the change in angle from one nucleotide to the next, the chains wind into a spiral called a double helix. Topic 25 Topic 25

46 Four different nitrogen bases are found in DNA: adenine, guanine, cytosine, and thymine. Base Pairing Biochemistry: Basic Concepts Adenine hydrogen bonds to thymine, and guanine hydrogen bonds to cytosine. Topic 25 Topic 25

47 The order of these four nitrogen bases along one of the DNA chains provides the information for the sequences of amino acids in proteins. Base Pairing Biochemistry: Basic Concepts Cell mechanisms read the DNA sequence in groups of three bases called triplets. Each triplet codes for a specific amino acid or tells the cell to start or stop making a protein. Topic 25 Topic 25

48 Basic Assessment Questions Question 1 Label the amino group and the carboxyl group of the dipeptide. Topic 25 Topic 25

49 Basic Assessment Questions Answer Topic 25 Topic 25

50 Basic Assessment Questions Question 2 Draw an arrow pointing to the peptide bond. Topic 25 Topic 25

51 Basic Assessment Questions Answer Topic 25 Topic 25

52 Basic Assessment Questions Question 3 Draw a square around each variable side chain. Topic 25 Topic 25

53 Basic Assessment Questions Answer Topic 25 Topic 25

54 Basic Assessment Questions Glucose is a(n) Question 4 a. polysaccharide. b. amino acid. c. part of cellulose. d. 5-carbon sugar. Topic 25 Topic 25

55 Basic Assessment Questions Answer The answer is C, part of cellulose. Topic 25 Topic 25

56 Biochemistry: Additional Concepts Topic 25 Topic 25 Additional Concepts

57 Biochemistry: Additional Concepts Anabolism and Catabolism The set of reactions carried out by an organism is its metabolism. Living organisms must accomplish two major functions in order to survive. They have to extract energy from nutrients in forms that they can use immediately as well as store for future use. Topic 25 Topic 25

58 Biochemistry: Additional Concepts Anabolism and Catabolism In addition, they have to use nutrients to make building blocks for synthesizing all of the molecules needed to carry out their life functions. Topic 25 Topic 25

59 Biochemistry: Additional Concepts Anabolism and Catabolism A large number of different metabolic reactions take place in living cells. Some involve breaking down nutrients to extract energy; these are catabolic processes. Topic 25 Topic 25

60 Biochemistry: Additional Concepts Anabolism and Catabolism Others involve using energy to build large biological molecules; these reactions are anabolic processes. Topic 25 Topic 25

61 Biochemistry: Additional Concepts Anabolism and Catabolism The term catabolism refers to the metabolic reactions that break down complex biological molecules such as proteins, polysaccharides, triglycerides, and nucleic acids for the purposes of forming smaller building blocks and extracting energy. The term anabolism refers to the metabolic reactions that use energy and small building blocks to synthesize the complex molecules needed by an organism. Topic 25 Topic 25

62 Biochemistry: Additional Concepts ATP Catabolism and anabolism are linked by common building blocks that catabolic reactions produce and anabolic reactions use. A common form of potential chemical energy also links the two processes. Topic 25 Topic 25

63 Biochemistry: Additional Concepts ATP ATP (adenosine triphosphate) is a nucleotide that functions as the universal energy-storage molecule in living cells. During catabolic reactions, cells harness the chemical energy of foods and store it in the bonds of ATP. Topic 25 Topic 25

64 Biochemistry: Additional Concepts Photosynthesis What is the source of the energy that fuels metabolism? For most living things, certain wavelengths of sunlight provide all of this energy. Some bacteria and the cells of all plants and algae, including the brown algae, are able to capture light energy and convert some of it to chemical energy. Topic 25 Topic 25

65 Biochemistry: Additional Concepts Photosynthesis Animals cant capture light energy, so they get energy by eating plants or by eating other animals that eat plants. The process that converts energy from sunlight to chemical energy in the bonds of carbohydrates is called photosynthesis. Topic 25 Topic 25

66 Biochemistry: Additional Concepts Photosynthesis ATP is a nucleotide that contains an adenine nitrogen base, a ribose sugar, and three phosphate groups. Topic 25 Topic 25

67 Biochemistry: Additional Concepts Photosynthesis When the final phosphate group is removed from ATP, as modeled by the red dotted line, ADP is formed and energy is released. Topic 25 Topic 25

68 Biochemistry: Additional Concepts Photosynthesis During the complex process of photosynthesis, carbon dioxide and water provide the carbon, hydrogen, and oxygen atoms that make up carbohydrates and oxygen gas, which also is formed. The following net reaction takes place during photosynthesis. Topic 25 Topic 25

69 Biochemistry: Additional Concepts Photosynthesis Photosynthesis results in the reduction of the carbon atoms in carbon dioxide as glucose is formed. During this redox process, oxygen atoms in water are oxidized to oxygen gas. Topic 25 Topic 25

70 Biochemistry: Additional Concepts Cellular Respiration Most organisms need oxygen to live. Oxygen that is produced during photosynthesis is used by living things during cellular respiration, the process in which glucose is broken down to form carbon dioxide, water, and large amounts of energy. Cellular respiration is a redox process; the carbon atoms in glucose are oxidized while oxygen atoms in oxygen gas are reduced to the oxygen in water. Topic 25 Topic 25

71 Biochemistry: Additional Concepts Cellular Respiration The net reaction that takes place during cellular respiration is Note that the net equation for cellular respiration is the reverse of the net equation for photosynthesis. These two processes complement each other in nature. Topic 25 Topic 25

72 Biochemistry: Additional Concepts Fermentation During cellular respiration, glucose is completely oxidized, and oxygen gas is required to act as the oxidizing agent. Can cells extract energy from glucose in the absence of oxygen? Yes, but not nearly as efficiently. Without oxygen, only a fraction of the chemical energy of glucose can be released. Topic 25 Topic 25

73 Biochemistry: Additional Concepts Fermentation Whereas cellular respiration produces 38 moles of ATP for every mole of glucose catabolized in the presence of oxygen, only two moles of ATP are produced per mole of glucose that is catabolized in the absence of oxygen. Topic 25 Topic 25

74 Biochemistry: Additional Concepts Fermentation This provides enough energy for oxygen- deprived cells so that they dont die. The process in which glucose is broken down in the absence of oxygen is known as fermentation. There are two common kinds of fermentation. In one, ethanol and carbon dioxide are produced. In the other, lactic acid is produced. Topic 25 Topic 25

75 Biochemistry: Additional Concepts Alcoholic fermentation Yeast and some bacteria can ferment glucose to produce the alcohol ethanol. Topic 25 Topic 25

76 Biochemistry: Additional Concepts Alcoholic fermentation Topic 25 Topic 25

77 Biochemistry: Additional Concepts Alcoholic fermentation Alcoholic fermentation is needed to make bread dough rise, form tofu from soybeans, and produce the ethanol in alcoholic beverages. Another use of the ethanol that is produced by yeast is as an additive to gasoline, called gasohol. Topic 25 Topic 25

78 Biochemistry: Additional Concepts Lactic acid fermentation During strenuous activity, muscle cells often use oxygen faster than it can be supplied by the blood. When the supply of oxygen is depleted, cellular respiration stops. Topic 25 Topic 25

79 Biochemistry: Additional Concepts Lactic acid fermentation Although animal cells cant undergo alcoholic fermentation, they can produce lactic acid and a small amount of energy from glucose through lactic acid fermentation. Topic 25 Topic 25

80 Biochemistry: Additional Concepts Lactic acid fermentation Topic 25 Topic 25

81 Biochemistry: Additional Concepts Lactic acid fermentation The lactic acid that is produced is moved from the muscles through the blood to the liver. There, it is converted back into glucose that can be used in catabolic processes to yield more energy once oxygen becomes available. Topic 25 Topic 25

82 Biochemistry: Additional Concepts Lactic acid fermentation However, if lactic acid builds up in muscle cells at a faster rate than the blood can remove it, muscle fatigue results. Buildup of lactic acid is what causes a burning pain in the muscle during strenuous exercise. Topic 25 Topic 25

83 Additional Assessment Questions What effect do enzymes have on the chemical reactions that take place in living things? Question 1 Topic 25 Topic 25

84 Additional Assessment Questions speed reactions by lowering activation energy Answer Topic 25 Topic 25

85 Additional Assessment Questions Your cells carry out cellular respiration. What is the function of this process? Question 2 Topic 25 Topic 25

86 Additional Assessment Questions releases energy for life processes Answer Topic 25 Topic 25

87 Additional Assessment Questions What process is the reverse of cellular respiration? Question 3 Topic 25 Topic 25

88 Additional Assessment Questions photosynthesis Answer Topic 25 Topic 25

89 To advance to the next item or next page click on any of the following keys: mouse, space bar, enter, down or forward arrow. Click on this icon to return to the table of contents Click on this icon to return to the previous slide Click on this icon to move to the next slide Click on this icon to open the resources file. Help Click on this icon to go to the end of the presentation.

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