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  1. 1. The Structure and Function of Macromolecules AP Biology Chapter 5
  2. 2. Macromolecules <ul><li>Macromolecules are giant molecules . </li></ul><ul><li>Four main classes of macromolecules are: </li></ul><ul><li>Carbohydrates </li></ul><ul><li>Lipids </li></ul><ul><li>Proteins </li></ul><ul><li>Nucleic Acids </li></ul>
  3. 3. Polymers <ul><li>A polymer is a long molecule made of many similar or identical monomers (small molecules). </li></ul><ul><li>Polymers are linked by covalent bonds. </li></ul><ul><li>The covalent bonds occur through condensation reactions called dehydration. </li></ul><ul><li>The polymers are disassembled by a hydrolysis reaction. </li></ul>
  4. 5. Dehydration Reactions <ul><li>Condensation involves a dehydration synthesis because a water is removed (dehydration) and a bond is made (synthesis). </li></ul><ul><li>When two monomers join, a hydroxyl (OH) group is removed from one monomer and a hydrogen (H) is removed from the other. </li></ul><ul><li>This produces the water given off during a condensation reaction. </li></ul>
  5. 7. Carbohydrates <ul><li>in short-term energy storage </li></ul><ul><li>as intermediate-term energy storage (starch for plants and glycogen for animals); </li></ul><ul><li>as structural components in cells (cellulose in the cell walls of plants and many protists), and chitin in the exoskeleton of insects and other arthropods. </li></ul>Carbohydrates function:
  6. 8. Monosaccharides <ul><li>Monosaccharides are single (mono=one) sugars. </li></ul><ul><li>Sugars are structurally the simplest carbohydrates. </li></ul><ul><li>They are the structural unit which makes up the other types of carbohydrates. </li></ul><ul><li>Important monosaccharides include ribose, glucose, and fructose. </li></ul>
  7. 10. Disaccharides <ul><li>Disaccharides are formed when two monosaccharides are chemically bonded together. </li></ul><ul><li>Sucrose, a common plant disaccharide is composed of the monosaccharides glucose and fructose. </li></ul><ul><li>Lactose, milk sugar, is a disaccharide composed of glucose and the monosaccharide galactose. </li></ul>
  8. 12. Polysaccharides <ul><li>Polysaccharides are large molecules composed of individual monosaccharide units. </li></ul><ul><li>A common plant polysaccharide is starch, which is made up of many glucoses. </li></ul><ul><li>Glycogen is an animal storage product that accumulates in the vertebrate liver. </li></ul><ul><li>Cellulose is a polysaccharide found in plant cell walls. Cellulose forms the fibrous part of the plant cell wall. </li></ul>
  9. 13. Amylopectin
  10. 14. Lipids <ul><li>Lipids are involved mainly with long-term energy storage. </li></ul><ul><li>They are generally insoluble in polar substances such as water. </li></ul><ul><li>Secondary functions of lipids are as structural components and as hormones that play roles in communications within and between cells. </li></ul><ul><li>Lipids are composed of three fatty acids (usually) covalently bonded to a 3-carbon glycerol. </li></ul>
  11. 15. Fatty Acids <ul><li>Fatty acids can be </li></ul><ul><li>saturated (meaning they have as many hydrogens bonded to their carbons as possible) or </li></ul><ul><li>unsaturated (with one or more double bonds connecting their carbons, hence fewer hydrogens). </li></ul>
  12. 17. Fats <ul><li>A fat is solid at room temperature, while an oil is a liquid under the same conditions. </li></ul><ul><li>The fatty acids in oils are mostly unsaturated, while those in fats are mostly saturated. </li></ul>
  13. 19. Fats and Oils <ul><li>Fats and oils function in energy storage. </li></ul><ul><li>Animals convert excess sugars into fats. </li></ul><ul><li>Most plants store excess sugars as starch, although some seeds and fruits have energy stored as oils </li></ul>
  14. 20. Fats <ul><li>Another use of fats is as insulators and cushions. </li></ul><ul><li>The human body naturally accumulates some fats in the &quot;posterior&quot; area. </li></ul><ul><li>Subdermal (&quot;under the skin&quot;) fat plays a role in insulation. </li></ul>
  15. 21. Phospholipids <ul><li>Phospholipids and glycolipids are important structural components of cell membranes. </li></ul>
  16. 23. Waxes <ul><li>Waxes are an important structural component for many organisms, such as the cuticle, a waxy layer covering the leaves and stems of many land plants; and protective coverings on skin and fur of animals. </li></ul>
  17. 24. Cholesterol and Steroids <ul><li>Cholesterol and steroids : Most mention of these two in the news is usually negative. </li></ul><ul><li>Cholesterol has many biological uses, such as its occurrence in the cell membranes, and its role in forming the sheath of some neurons. </li></ul>
  18. 25. Proteins <ul><li>Proteins are very important as control and structural elements. </li></ul><ul><li>Control functions of proteins are carried out by enzymes and proteinaceous hormones. </li></ul>
  19. 26. Enzymes <ul><li>Enzymes are chemicals that act as organic catalysts (a catalyst is a chemical that promotes but is not changed by a chemical reaction). </li></ul>
  20. 27. Structural Proteins <ul><li>Structural proteins function in the cell membrane, muscle tissue, etc. </li></ul>
  21. 28. Proteins <ul><li>The building block of any protein is the amino acid, which has an amino end (NH2) and a carboxyl end (COOH). </li></ul><ul><li>The R indicates the variable component of each amino acid. </li></ul>
  22. 29. Basic Amino Acid
  23. 30. Amino Acids
  24. 31. Evolutionary Significance <ul><li>All living things use various combinations of the same twenty amino acids. A very powerful bit of evidence for the phylogenetic connection of all living things. </li></ul>
  25. 32. Peptide Bond <ul><li>Amino acids are linked together by joining the amino end of one molecule to the carboxyl end of another. Removal of water allows formation of a type of covalent bond known as a peptide bond. </li></ul>
  26. 34. Primary Structure <ul><li>Amino acids are linked together into a polypeptide, the primary structure is the sequence of amino acids in a polypeptide. </li></ul>
  27. 36. Secondary Structure <ul><li>The secondary structure is the tendency of the polypeptide to coil or pleat due to H-bonding between R-groups. </li></ul>
  28. 38. Tertiary Structure <ul><li>The tertiary structure is controlled by bonding (or in some cases repulsion) between R-groups. </li></ul><ul><li>The protein tends to fold upon itself. </li></ul>
  29. 40. Quaternary Structure <ul><li>Many proteins, such as hemoglobin, are formed from one or more polypeptides. Such structure is termed quaternary structure. </li></ul>
  30. 42. Nucleic Acids <ul><li>Nucleic acids are polymers composed of units known as nucleotides. </li></ul><ul><li>The main functions of nucleotides are information storage (DNA), protein synthesis (RNA), and energy transfers (ATP and NAD). </li></ul>
  31. 43. Nucleic Acids Cont’d <ul><li>Nucleotides consist of a sugar, a nitrogenous base, and a phosphate. The sugars are either ribose or deoxyribose. </li></ul><ul><li>There are five nitrogenous bases. Purines (Adenine and Guanine) are double-ring structures, while pyrimidines (Cytosine, Thymine and Uracil) are single-ringed. </li></ul>
  32. 45. DNA <ul><li>Deoxyribonucleic acid (better known as DNA) is the physical carrier of inheritance for 99% of living organisms. The bases in DNA are C, G, A and T. </li></ul>
  33. 47. RNA <ul><li>RNA functions in protein synthesis. </li></ul><ul><li>There are three types of RNA, each is involved in protein synthesis. </li></ul><ul><li>Messenger RNA (mRNA) is the blueprint for construction of a protein. </li></ul><ul><li>Ribosomal RNA (rRNA) is the construction site where the protein is made. </li></ul><ul><li>Transfer RNA (tRNA) is the truck delivering the proper amino acid to the site at the right time. </li></ul>