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Chapter 13 Biochemistry: A Molecular View of Life

Chapter 13 Biochemistry: A Molecular View of Life. Biochemistry. Chemistry of living things and life processes Cell: structural unit for all living things Cell membrane defines cell and lets material flow into and out of cell Plant cells: also have walls made of cellulose

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Chapter 13 Biochemistry: A Molecular View of Life

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  1. Chapter 13Biochemistry: A Molecular View of Life

  2. Biochemistry • Chemistry of living things and life processes • Cell: structural unit for all living things • Cell membrane defines cell and lets material flow into and out of cell • Plant cells: also have walls made of cellulose • Animal cells: do not have cell walls Chapter 15

  3. Plant Cells Chapter 15

  4. Animal Cells Chapter 15

  5. Major Internal Structures • Cell nucleus: contains material that controls heredity • Ribosomes: carry out protein synthesis • Mitochondria: produce energy • Chloroplasts: only in plant cells • Convert solar energy into chemical energy Chapter 15

  6. Metabolism • Series of coordinated reactions that keeps cells alive • Catabolism: reactions that break down molecules for energy • Anabolism: synthesize molecules of living systems Chapter 15

  7. Carbohydrates • Sugars, starches, and cellulose • General formula: Cx(H2O)y • Sugars: sweet tasting carbohydates • Aldoses: aldehyde functional group • Ketoses: ketone functional group • Monosaccharides: simplest sugars Chapter 15

  8. Chapter 15

  9. Polysaccharides • Contain two or more monosaccharides • Main energy storage system: starch • Plants use them for cell walls: cellulose • Both are polymers of glucose • Difference in way they are linked together • Determines chemistry Chapter 15

  10. Starch • Two kinds in plants • Both made of glucose • Amylose: straight chain • Amylopectin: branched chain Chapter 15

  11. Glycogen • Another kind of starch found in animals • Made of glucose - branched chain The structure of glycogen is similar to that of amylopectin, although the branches in glycogen tend to be shorter and more frequent Allows more ends to undergo a more rapid hydrolysis to release glucose for energy requirement Chapter 15

  12. CELLULOSE • A polymer of glucose molecules with beta linkage • Beta linkage Does not allow for chain of molecules to coil Chains can align with one another to form fibers Fibers can lay down in a criss-cross pattern Hydrogen bonding Criss-cross pattern gives strength in many directions • Cannot be digested by animals and therefore serves as dietary fiber to help regulate bowel movement Chapter 15

  13. Lipids • Defined by solubility • Insoluble in water • Fats are largest subgroup of lipids • Made up of fatty acids and glycerol Chapter 15

  14. Some Naturally Occurring Fatty Acids Chapter 15

  15. Saturated vs. Unsaturated Fats • Saturated fats have no C=C bonds • Saturated with hydrogen • Unsaturated fats have C=C bonds • May have more than one double bond • Can add more hydrogen to fats • React readily with iodine, bromine, and chlorine Chapter 15

  16. Iodine Number • Iodine Number: number of grams of iodine consumed by 100 g of fat Chapter 15

  17. Proteins • Serve as structural material for animals • Required in all living cells • Composed of carbon, hydrogen, oxygen, and usually sulfur Chapter 15

  18. Amino Acids • Building blocks for polymers called proteins • Contain an amino group, –NH2, and a carboxylic acid, –COOH • Can form zwitterions: have both positively charged and negatively charged groups on same molecule • 20 required for humans Chapter 15

  19. Chapter 15

  20. Chapter 15

  21. Peptide Bond • Connect amino acids from carboxylic acid to amino group • Produce amide linkage: -CONH- • Holds all proteins together • Indicate proteins by 3-letter abbreviation Chapter 15

  22. Sequence of Amino Acids • Amino acids need to be in correct order for protein to function correctly • Similar to forming sentences out of words Chapter 15

  23. Structure of Proteins • Four organizational levels • Primary structure: amino acid sequence • Secondary structure: arrangement of chains around an axis • Pleated sheet • Alpha helix: right-handed helix Chapter 15

  24. Pleated Sheets Chapter 15

  25. Alpha Helix Chapter 15

  26. Tertiary Structure • Spatial relationships of amino acids relatively far apart in protein chain • Globular proteins: compact spherical shape Chapter 15

  27. Quaternary Structure • Structure when two or more amino acid sequences are brought together • Hemoglobin has four units arranged in a specific pattern Chapter 15

  28. Intermolecular Forces in Proteins • Hydrogen bonding • Ionic bonds • Disulfide linkages • Dispersion forces Chapter 15

  29. Enzymes • Biological catalysts produced by cells • Nearly all are proteins • Enormous catalytic power • Reactions occur at lower temperatures and at higher rates • Ordinarily highly specific Chapter 15

  30. Induced-Fit Model of Enzymes • Explains how enzyme works • Substrate: reacting substance • Active site: where chemical reaction takes place and where substrate fits Chapter 15

  31. Cofactors • Something other than polypeptide chain required by enzyme • May be metal • Iron in hemoglobin • May be organic cofactor • Coenzyme • Apoenzyme: does not have cofactor Chapter 15

  32. Inhibition of Enzymes • Lets cell control when an enzyme works • Inhibitor binds to allosteric site • Prevents substrate from binding Chapter 15

  33. Nucleic Acids • Serve as information and control center of the cell • Deoxyribonucleic acid (DNA) • Carries blueprint for proteins • Found in cell nucleus • Ribonucleic acid (RNA) • Carries out protein assembly • Found in all parts of the cell Chapter 15

  34. Nucleotides • Three components • Sugar • Either ribose or deoxyribose • Phosphate unit • Nucleic acid • Purines: two fused rings • Pyrimidines: one ring Chapter 15

  35. Nucleotides • Four bases in DNA • Pair up in a specific pattern Chapter 15

  36. DNA • When all base pairs are paired up with second strand – form double helix • Held together by hydrogen bonding Chapter 15

  37. RNA • Tends to form single strand • May pair up with itself Chapter 15

  38. Genetic Information • Chromosomes: hereditary material, concentrated in long threadlike bodies • 46 in humans • Made of protein and DNA • Gene: basic unit of heredity • Section of DNA • Genome is complete set of genes for an organism Chapter 15

  39. Chapter 15

  40. Self-Replication Occurs every time a cell divides Chapter 15

  41. Transcription • Converts DNA code to RNA • Must occur before protein synthesis • Can make multiple copies to make multiple copies of the protein Chapter 15

  42. Translation • Converts code on RNA into protein • Read using base triplet • Code for amino acids • Some redundancy Chapter 15

  43. Chapter 15

  44. Polymerase Chain Reaction (PCR) • Method to rapidly amplify any DNA present in sample • Can use very small amounts of DNA • Allows for genetic testing • Cut DNA into relatively small sizes • Amplify it to see any pattern Chapter 15

  45. Recombinant DNA • Allows for addition of genes to organisms • Make microorganisms produce useful drugs • All insulin is made this way • Rapidly change genetics of plants • Treat genetic disorders in humans Chapter 15

  46. Chapter 15

  47. End of Chapter 15 Chapter 15

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