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Chapter 13 .Chemicals of life

Chapter 13 .Chemicals of life. No molecule in a living organism is a permanent resident. Within 7 years, most of the molecules in a human body have been replaced by new one!

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Chapter 13 .Chemicals of life

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  1. Chapter 13 .Chemicals of life No molecule in a living organism is a permanent resident. Within 7 years, most of the molecules in a human body have been replaced by new one! Individual? Decided completely by the genetic code? No! An individual’s identity is continually re-established each and every moment.

  2. 13.1 Biomolecules are produced and utilized in cells • Plasma membrane: 细胞膜 • Cell wall: 细胞壁 • Cell nucleus：细胞核 • Cytoplasm: 细胞质 • Organelles: 细胞器 • Carbohydrate: 碳水化合物 • Lipid: 脂类 • Protein: 蛋白质 • Nucleic acid: 核酸 Plant cell Animal cell

  3. 13.2 Carbohydrates give structure and energy • Carbohydrates are molecules of carbon, hydrogen and oxygen produced by plant through photosysthesis (光合作用). • Saccharide: 糖类 • Glucose: 葡萄糖 • Fructose: 果糖 Honey Glucose Fructose

  4. Sucrose: 蔗糖

  5. Lactose: 乳糖Lactase: 乳糖酶

  6. Polysaccharides (多糖) are complex carbohydrates Hyaluronic acid: 透明质酸 Glucuronic acid: 葡萄醛酸 Chitin: 甲壳素

  7. The polysaccharides of the human diet are made only of glucose. These polysaccharides include starch (淀粉), glycogen （糖原） and cellulose （纤维素）, which differ from one another in how the glucose units are chained together. Amylose: 直链淀粉20% Amylopectin: 支链淀粉80%

  8. Glycogen is found in animal tissue

  9. Cellulose is consisted of β–glucose and has a straight conformation.Cellulose is by far the most abundant organic compound on earth. But most animals, including humans, are not able to break cellulose down to glycose.

  10. 13.3 Lipids are insoluble in water • Fats are used for energy and insulation • A fat is any biomolecule formed from the reaction of a glycerol molecule, attached to three fatty acid molecules. Fatty acid can be saturated or unsaturated. • Fats are used to reserve energy. 1 gram of fat contains about 9 calories of energy, while a gram of carbohydrate and protein contains only 4 calories of energy. • Fats are also used to insulate us from cold.

  11. Saturated fat and unsaturated fatThe molecules of saturated fats can pack together, leading to high melting points.The molecules of unsaturated fats can not pack together, leading to low melting points. stearic acid，m.p.69℃ oleic acid，m.p.13℃

  12. Fats from animals and plants are mixture of different fat molecules Table 13.1 degree of unsaturation in some common fats

  13. Steroids (类固醇) contain four carbon rings • Cholesterol: 胆固醇 • Testosterone: 睾酮 • Estradiol: 雌甾二醇

  14. 13.4 Proteins are polymers of amino acids (氨基酸) • 20 amino acids differ from one another by the chemical identity of their side groups.

  15. Amino acids are linked through peptide bonds (肽键). A group of amino acids linked together through peptide bonds is called peptide. Peptides containing more than ten amino acids are generally called polypeptides.

  16. There are many kinds of proteins

  17. Protein structure is determined by attractions between neighboring amino acids

  18. The proteins in hair and fingernails contain a lot of disulfide bonds

  19. Many proteins consist of two or more polypeptide chains. 血红蛋白 The proteins can be denatured with the change in conditions.

  20. Enzymes are biological catalysts Figure 13.25 Upon binding to the receptor site on the enzyme sucrase, the substrate sucrose is split into its two monosac-charide units, glucose and fructose.

  21. 13.5 Nucleic acids code for proteins • Our bodies are built of proteins. Our bodies are able to assemble amino acids in just the right order to build proteins that have highly functional structures. • A nucleotide (核苷) consists of a phosphate (磷酯), a ribose sugar (核糖), and a nitrogenous base (碱基). • A nucleic acid is a polymer made up to nucleotide monomers.

  22. Two types of nucleic acids: deoxyribonucleic acid (脱氧核糖核酸) and ribonucleic acid (核糖核酸). • Deoxyribonucleic acids are the primary source of genetic information and are found in the cell nucleus. • Ribonucleic acids occur mostly outside the cell nucleus in the cytoplasm, where they piece together amino acids to make proteins.

  23. DNA is the template of life • Gregor Mendel’s work rose the idea of heredity. The unit containing the heritable information is called genes. In 1900s, genes have been related to chromosomes (染色体), which consist of DNA and proteins.

  24. In 1953, James Watson and Francis Crick proposed the double helix structure of DNA. The most critical point of double helix model is the hydrogen bonding between guanine and cytosine, and also between adenine and thymine.

  25. Replication of DNA

  26. One gene codes for one polypeptide • Gene controls the protein’s amino acid sequence. Each gene codes for the synthesis of a particular protein. • The number of human gene is 30000-100000. • Each chromosome contains 1000-2000 genes. • Each DNA molecule contains about 3.1 billion base pairs. • Genes make up only about 20% of a DNA molecule.

  27. RNA is largely responsible for protein synthesis • The manufacturing of proteins involves two processes: transcription (转录) and translation (转译). • These steps are mediated by the three forms of RNA: messenger RNA (信使RNA，mRNA), ribosomal RNA (核糖体RNA，rRNA) and transfer RNA (转移RNA，tRNA).

  28. Codon （密码子、三联体）

  29. Translation

  30. Ribosome Ribosome

  31. Genetic engineering • Restriction enzyme (限制酶) ban cleave long strands of DNA into small fragments. • Gel electrophoresis is used to separate fragmented DNA. Gel electrophoresis

  32. Recombinant （重组）DNA

  33. Gene cloning (基因克隆)

  34. 13.6 Vitamins are organic, minerals are inorganic • Lipid-soluble vitamins and water-soluble vitamins • Lipid-soluble vitamins can be stored in body for long time, but not for children. • Over-dose of vitamins A and D are harmful. • Vitamins B and C are washed away by water.

  35. Table 13.2 Some Vitamins Needed by the Human Body

  36. Minerals Table 13.3 Some Macrominerals Needed by the Human Body

  37. ATP&ADP

  38. 13.7 Metabolism (代谢) is the cycling of biomolecules through the body catabolism and metabolism

  39. 13.8 The food pyramid summarizes a healthful diet

  40. CarbohydratesGlycemic Index （血糖指数） Table 13.4 Glycemic Index for Select Foods source: Jennie Brand Miller et al., the Glucose Revolution: the authoritative guide to the Glycemic index. Sydney: Marlowe & company, 1999

  41. Unsaturated fats are generally more healthful than saturated fatsSaturated fats are used to synthesize cholesterol.Fats are also packaged with water soluble proteins (Lipoproteins) to move through bloodstream. • Hydrogenation of unsaturated fats can be used to prepare margarine and also in the process of making chocolates. Table 13.5 The Classification of Lipoproteins

  42. Essential for children Essential for adults

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