Chapter 20


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Chapter 20

  1. 1. Chapter 20 Carbohydrates and Lipids
  2. 2. Carbohydrates and Living Systems <ul><li>A monosaccharide (C 6 H 12 O 6 ) is a simple sugar that is the basic subunit of a carbohydrate. </li></ul><ul><li>A disaccharide (C 12 H 22 O 11 ) is a sugar formed from two monosaccharides. </li></ul><ul><li>A polysaccharide is one of the carbohydrates made up of long chains of simple sugars. </li></ul>
  3. 3. Carbohydrates and Living Systems <ul><li>Polysaccharides include starch, glycogen, and cellulose. </li></ul><ul><li>Potatoes have a lot of starch , the polysaccharide that plants use for storing energy. </li></ul><ul><li>Many animals make use of a similar energy-storage carbohydrate called glycogen . </li></ul><ul><li>Cellulose is the polysaccharide that most plants use to give their structures rigidity. </li></ul>
  4. 4. To a chemist, sugar is the name given to all monosaccharides and disaccharides.
  5. 5. Each molecule of sucrose, the sugar used to sweeten food, is made up of a glucose and a fructose unit.
  6. 6. Carbohydrates <ul><li>Just as two monosaccharides combine to form a disaccharide, many can combine to form a long chain called a polysaccharide. </li></ul><ul><li>Polysaccharides may be represented by the general formula below. </li></ul>— O—(C 6 H 10 O 4 )—O—(C 6 H 10 O 4 )—O—(C 6 H 10 O 4 )...
  7. 7. Carbohydrates <ul><li>Polymerization is a series of synthesis reactions that link many monomers together to make a very large, chainlike molecule. </li></ul><ul><li>Polysaccharides and other large, chainlike molecules found in living things are called biological polymers . </li></ul>
  8. 10. Carbohydrate Reactions <ul><li>Polysaccharides are changed back to sugars during hydrolysis reactions. </li></ul><ul><li>In these reactions, the decomposition of a biological polymer takes place along with the breakdown of a water molecule, as shown in the equation below. </li></ul>
  9. 12. Lipids <ul><li>A lipid is a type of biochemical that does not dissolve in water, including fats and steroids. </li></ul><ul><li>Lipids generally can have a polar, hydrophilic region at one end of the molecule. For example, oleic acid, shown below is found in the fat of some animals. </li></ul>
  10. 14. Lipids <ul><li>Lipids are used in animals for energy storage as fats . </li></ul><ul><li>Cell membranes are made up of lipids called phospholipids . </li></ul><ul><li>Steroids , such as cholesterol, are lipids used for chemical signaling. </li></ul><ul><li>Waxes , such as those found in candles and beeswax are also lipids. </li></ul>
  11. 16. Chapter 20 Proteins
  12. 17. Amino Acids and Proteins <ul><li>A protein is a biological polymer that is made up of nitrogen, carbon, hydrogen, oxygen, and sometimes other elements. </li></ul><ul><li>Our bodies are mostly made out of proteins. </li></ul><ul><li>All proteins are biological polymers made up of amino acid monomers. </li></ul><ul><li>An amino acid is any one of 20 different organic molecules that contain a carboxyl and an amino group and that combine to form proteins. </li></ul>
  13. 19. Amino Acids and Proteins <ul><li>Amino refers to the −NH2 group of atoms. </li></ul><ul><li>Acid refers to the carboxylic acid group, −COOH. </li></ul><ul><li>There are 20 natural amino acids. All 20 have the same basic structure. </li></ul>
  14. 20. The R represents a side chain.
  15. 22. Amino Acids and Proteins <ul><li>The reaction by which proteins are made from amino acids is similar to the condensation of carbohydrates. </li></ul><ul><li>The biological polymer that forms during the condensation of amino acids is called a polypeptide. </li></ul><ul><li>The link that joins the N and C atoms of two different amino acids is called a peptide bond. </li></ul>
  16. 26. Amino Acids and Proteins <ul><li>The sequence of amino acids—the primary structure—helps dictate the protein’s final shape. </li></ul><ul><li>A substitution of just one amino acid in the polypeptide sequence can have major effects on the final shape of the protein. </li></ul><ul><li>A hereditary blood cell disease called sickle cell anemia gives one example of the importance of amino-acid sequence. </li></ul>
  17. 28. Enzymes <ul><li>An enzyme is a type of protein that speeds up metabolic reactions in plant and animals without being permanently changed or destroyed. </li></ul><ul><li>Almost all of the chemical reactions in living systems take place with the help of enzymes . </li></ul>
  18. 29. Enzymes <ul><li>Enzymes work like a lock and key. That is, only an enzyme of a specific shape can fit the reactants of the reaction that it is catalyzing. </li></ul><ul><li>Only a small part of the enzyme’s surface, known as the active site , is believed to make the enzyme active. </li></ul><ul><li>In reactions that use an enzyme, the reactant is called a substrate . </li></ul>
  19. 31. Chapter 20 Nucleic Acids
  20. 32. Information Storage <ul><li>All hereditary information is stored chemically in compounds called nucleic acids. </li></ul><ul><li>Nucleic acids are an organic compound, either RNA or DNA, whose molecules are made up of one or two chains of nucleotides and carry genetic information. </li></ul>
  21. 33. Nucleic-Acid Structure <ul><li>Like polysaccharides and polypeptides, nucleic acids are biological polymers. They are made up of monomers called nucleotides. </li></ul>
  22. 35. Information Storage <ul><li>The nucleic acid DNA, or deoxyribonucleic acid, is the material that contains the information that determines inherited characteristics. </li></ul><ul><li>The sugar in DNA is deoxyribose, which has a ring in which four of the atoms are carbon and the fifth atom is oxygen. </li></ul><ul><li>Deoxyribose is connected to a phosphate group and any one of four nitrogenous bases. </li></ul>
  23. 36. Information Strorage <ul><li>The nucleic acid DNA, or deoxyribonucleic acid, is the material that contains the information. </li></ul><ul><li>The sugar in DNA is deoxyribose, which has a ring in which four of the atoms are carbon and the fifth atom is oxygen. </li></ul><ul><li>Deoxyribose is connected to a phosphate group and any one of four nitrogenous bases. </li></ul>
  24. 40. Information Storage <ul><li>All genetic information is encoded in the sequence of the four bases, which are abbreviated to A, G, T, and C. </li></ul><ul><li>Just as history is written in books using a 26-letter alphabet, heredity is written in DNA using a 4-letter alphabet. </li></ul>
  25. 42. Gene Technology <ul><li>Because no one else has the same sequence of DNA bases as you, your DNA pattern gives a unique “fingerprint” of you. </li></ul><ul><li>A DNA fingerprint is the pattern of bands that results when an individual’s DNA sample is fragmented, replicated, and separated. </li></ul><ul><li>In DNA fingerprinting, scientists compare autoradiographs, which are images that show the DNA’s pattern of nitrogenous bases. </li></ul>
  26. 44. Gene Technology <ul><li>It takes a lot of DNA to make a DNA fingerprint, so scientists must replicate DNA to get a large sample. </li></ul><ul><li>Scientists use polymerase chain reaction, or PCR, to replicate a sequence of double-stranded DNA. </li></ul><ul><li>In PCR, scientists add DNA monomers, an enzyme, and primers (short lengths of single-stranded DNA with a specific sequence) to the sample of DNA. </li></ul><ul><li>Heating and cooling repeatedly replicates the DNA. </li></ul>
  27. 46. Gene Technology <ul><li>Each cell of a very young embryo can grow into a complete organism. These cells are undifferentiated. </li></ul><ul><li>Undifferentiated cells have not yet specialized to become part of a specific body tissue and include stem cells in animals and meristem cells in plants. </li></ul><ul><li>When they are cultured artificially they grow into complete organisms, clones, that are genetically identical to their “parent.” </li></ul>
  28. 48. Gene Technology <ul><li>Scientists can insert genes from one species into the DNA of another. </li></ul><ul><li>Recombinant DNA is DNA molecules that are created by combining DNA from different sources </li></ul><ul><li>When recombinant DNA is placed in a cell, the cell is able to make the protein coded by the foreign gene. </li></ul><ul><li>For example, recombinant DNA placed in bacteria cells allow the bacteria to make human insulin. </li></ul>
  29. 49. Chapter 20 Energy and Living Systems
  30. 50. Obtaining Energy <ul><li>Energy is needed for every action of every organ in our bodies. All living things need energy. </li></ul><ul><li>Plants get energy through photosynthesis, the process by which they use sunlight, carbon dioxide, and water to produce carbohydrates and oxygen. </li></ul><ul><li>Other living things rely on plants for energy. </li></ul><ul><li>The flow of energy throughout an ecosystem relates to the carbon cycle, which follows carbon atoms as they make up one compound and then another. </li></ul>
  31. 53. Obtaining Energy <ul><li>The carbon cycle involves two general reactions: photosynthesis and respiration. </li></ul><ul><li>The reactants needed for respiration—glucose and oxygen—are produced in photosynthesis. </li></ul><ul><li>The reactants needed for the photosynthesis—carbon dioxide, water, and energy—are produced in the respiration, although the energy is in a different form. </li></ul>
  32. 55. Using Energy <ul><li>Glucose is changed into a more readily available source of energy through respiration. </li></ul><ul><li>In biological chemistry, respiration is the process by which cells produce energy from carbohydrates. </li></ul><ul><li>In respiration (also called cellular respiration ), oxygen combines with glucose to form water and carbon dioxide. </li></ul>
  33. 56. <ul><li>For every molecule of glucose that is broken down, six molecules of O 2 are consumed. Six molecules of CO 2 and six molecules of H 2 O are produced. </li></ul>
  34. 57. Using Energy <ul><li>While photosynthesis takes in energy, respiration gives off energy. </li></ul><ul><li>The thermodynamic values for the equation below show that the reaction is very exothermic </li></ul><ul><li>( ∆H = −1273 kJ) </li></ul><ul><li>C6H12O6( aq ) + 6O2( g ) -> 6CO2( g ) + 6H2O( l ) </li></ul><ul><li>Respiration produces chemical energy (not heat energy) in the form of special organic molecules. </li></ul>
  35. 58. Using Energy <ul><li>Adenosine triphosphate, ATP, an organic molecule that acts as the main energy source for cell processes. </li></ul><ul><li>ATP is composed of a nitrogenous base, a sugar, and three phosphate groups. </li></ul><ul><li>Adenosine diphosphate, ADP, is the low-energy forms of a ATP. </li></ul>
  36. 59. <ul><li>The main structural difference between ATP and ADP is that ATP has an extra phosphate group, −PO 3 − . </li></ul>
  37. 61. Using Energy <ul><li>There are three kinds of work fueled by the ATP -> ADP conversion: </li></ul><ul><ul><li>Synthetic work involves making compounds that do not form spontaneously. </li></ul></ul><ul><ul><li>Mechanical work changes the shape of muscle cells, which allows muscles to flex and move. </li></ul></ul><ul><ul><li>Transport work involves carrying solutes across a membrane. </li></ul></ul>