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Molecules of life


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Molecules of Life

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Molecules of life

  2. 2. THE MOLECULES OF LIFE This Presentation is a “Mash up” of Five Presentations From Different Aouthers
  3. 3. The Simplest Hydrocarbon • Methane = Carbon + Hydrogen
  4. 4. Organic Molecules • A cell is mostly water but the rest consists mainly of carbon based molecules • Compounds that contain carbon are called organic compounds • Carbon has the ability to form the large, complex diverse, molecules necessary for life functions • Why are carbon atoms so versatile as molecular ingredients?
  5. 5. Carbon Chemistry • Carbon a versatile atom has 4 electrons in an outer shell that holds 8 - carbon can share its electrons with other atoms to form up to 4 covalent bonds • Carbon can use its bonds to attach to other carbons to form an endless diversity of carbon skeletons - each carbon in an organic molecule can branch off in up to 4 directions • Carbon atoms of organic molecules can also bond with other elements (hydrogen, oxygen, nitrogen) Copyright © 2007 Pearson Education, Inc. publishing as Pearson Benjamin Cummings
  6. 6. Variations in Carbon Skeletons • Simplest organic compounds are hydrocarbons • Hydrocarbons consist of carbon and hydrogen • Each C atom forms 4 bonds; each H atom forms 1 bond Fig 3.2
  7. 7. Larger Hydrocarbons • Main molecules in the gasoline we burn in our cars • Hydrocarbons of fat molecules provide energy for our bodies Fig 3.4
  8. 8. Functional Groups • Each type of organic molecule has a unique 3-dimensional shape that defines its function in an organism - the molecules of your body recognize one another based on their shapes • The unique properties of an organic compound depend not only on its carbon skeleton but also on the atoms attached to the skeleton - these atoms are called functional groups • Functional groups behave consistently from one organic molecule to another
  9. 9. 4 Important Functional Groups • Many biological molecules have 2 or more functional groups • How do cells make large molecules out of smaller organic molecules
  10. 10. Size of Molecules • Monomers – Molecules used as subunits to build larger molecules (polymers) • Polymers – Larger molecules that are chains of monomers – May be split and used for energy
  11. 11. Building Blocks • On a molecular scale, many of life’s molecules are gigantic - biologists call them macromolecules (macro = ‘big’) such as DNA, carbohydrates, proteins • Most macromolecules are polymers - polymers are made by stringing together many smaller molecules called monomers - cells link monomers together through a dehydration reaction (removes a molecule of water) • Organisms break down macromolecules (digestion) - cells do this by a process called hydrolysis (hydro = ‘water’ lyse = ‘break’; to break with water)
  12. 12. Dehydration Reaction Synthesis – a polymer grows in length when an incoming monomer and the monomer at the end of the existing chain contribute to the formation of a water molecule, the monomers then replace their lost covalent bonds with a bond to each other
  13. 13. Hydrolysis Breaking a polymer chain – hydrolysis reverses the process by breaking down the polymer with the addition of water molecules, which break the bonds between monomers
  14. 14. INPORTANT INORGANIC COMPOUNDS • Water • and minerals
  15. 15. Water • Most important biochemical: • A major component of cells (70-95% of cell mass) • Provides environment for those organisms that live in water (3/4 of the world) • Interesting features: • Exist in liquid form at normal Earth temperatures • Provides a medium for molecules and ions to mix in and hence a medium in which life could evolve • Hydrogen bonds • More energy needed to break bonds and convert water from liquid to a gas ALBIO9700/2006JK
  16. 16. Water as a solvent • Excellent solvent for ions and polar molecules because water molecules are attracted to them, collect around and separate them (dissolve) • Non-polar molecules are pushed together ALBIO9700/2006JK
  17. 17. Water as a transport medium • Blood • Lymphatic system • Excretory system • Digestive system • Vascular tissues of plants ALBIO9700/2006JK
  18. 18. Thermal properties • Hydrogen bonding restricts movement of water molecules – large amount of energy needed to raise temperature of water  Oceans and lakes are more stable habitats  Minimise internal (body) changes in temperature  Evaporation transfers a large amount of energy (cooling)  Water will not freeze easily ALBIO9700/2006JK
  19. 19. Density and freezing properties • Ice is less dense than liquid form • Acts as insulates • Changes in density of water with temperature cause currents which help to maintain the circulation of nutrients in the oceans ALBIO9700/2006JK
  20. 20. High surface tension and cohesion • Water molecules tend to stick to each other • Water movement through the vascular tissue in plants • Important property in cells • High surface tension (pond skater) ALBIO9700/2006JK
  21. 21. ALBIO9700/2006JK
  22. 22. 2. MINERALS a. elements extracted from the soil; consumed in our diet b. main minerals are calcium, phosphorus, potassium, sodium, chloride, magnesium, zinc, copper c. are crucial for synthesis and maintenance of: Bones Calcium, phosphorus Muscles Calcium, sodium, phosphorus Neurons Calcium, sodium, potassium, phosphorus
  23. 23. Text Reading: Chapter 2 (p35-40), Chapter 3 (p53-62, 70-75) You are What You Eat: Macromolecules of Life & Their Relationship to Diet and Nutrition Learning Objectives • Name the four major classes of biological macromolecules. Describe the composition and function of each. Provide examples of each. • Distinguish between steroids and anabolic steroids, and explain how the use of anabolic steroids can be dangerous to a person’s health. • Apply this information to interpreting a food label and categorize the food as either healthful or junk food.
  24. 24. Biological Macromolecules • There are four categories of macromolecules in cells: • • • • Carbohydrates Lipids Proteins Nucleic acids
  25. 25. Carbohydrates • Major source of energy for cells • Carbohydrates include • Simple sugar molecules (fructose, glucose, sucrose) – enter system quickly • Complex carbohydrates contain branched chains of simple sugars (starch, glycogen) – digested slowly
  26. 26. Carbohydrates (cont’d) • 3 classes of carbohydrates: • Monosaccharides • Disaccharides • Polysaccharides Figure 2.12
  27. 27. Monosaccharides • Monosaccharides are simple sugars. • Examples: glucose, fructose • Glucose found in sports drinks • Fructose found in fruit, corn syrup • Honey contains both glucose and fructose • Monosaccharides are the main fuel that cells use for cellular work.
  28. 28. Disaccharides • A disaccharide is a double sugar. • Constructed from two monosaccharides. – Examples: maltose, lactose, sucrose • Maltose is used to make beer, malted milk shakes, & malted milk ball candies.
  29. 29. Disaccharides (cont’d) • Lactose is another type of disaccharide. • Found in milk products. • lactose intolerance: inability to digest lactose • These people don’t make enough lactase, the enzyme the breaks down lactose.
  30. 30. Disaccharides (cont’d) • Most common disaccharide is sucrose (table sugar) • Consists of a glucose linked to a fructose. • Extracted from sugar cane and roots of sugar beets. – USA is one of the world’s leading markets for sweeteners. • Average American consumes ~64 kg (>140 lbs!!!) of sugar/year
  31. 31. Polysaccharides • Complex carbohydrates are called polysaccharides. • Long chains of sugar units. • Polymers of monosaccharides. – Examples: starch, glycogen, cellulose – Fiber is an indigestible complex carbohydrate
  32. 32. Proteins • Proteins perform most of the tasks the body needs to function. Structure Storage Contractile Proteins Signaling Proteins Hormones Enzymes Defense (Antibodies) Transport
  33. 33. The Monomers: Amino Acids • Proteins are polymers of amino acids. • All proteins are constructed from a common set of 20 kinds of amino acids. – Each amino acid consists of • A central carbon atom bonded to four covalent partners. • Side group is variable among all 20. • The side group gives each amino acid its properties.
  34. 34. Proteins as Polymers • Cells link amino acids together to form proteins. • The resulting bond between them is called a peptide bond. • String of amino acids sometimes called polypeptide. Figure 2.13
  35. 35. Protein Diversity – Your body has tens of thousands of different kinds of proteins. – Different combinations of amino acids give proteins different properties. – Most proteins are at least 100 amino acids in length. – Many different sequences possible with 20 amino acids. – Analogy: 26 letters can make many different words
  36. 36. Protein Structure • Primary structure • Sequence of amino acids in a protein – A slight change in the primary structure of a protein affects its ability to function. • The substitution of one amino acid in hemoglobin causes sickle-cell disease.
  37. 37. Protein Shape • Proteins have four levels of structure. Sequence of amino acids Local folding patterns Examples: alpha helix, beta pleated sheet Overall three-dimensional shape Overall shape when two or more polypeptides bind each other
  38. 38. What Determines Protein Structure? • A protein’s amino acid sequence dictates its structure. • A protein’s shape is also sensitive to the surrounding environment. • Unfavorable temperature and pH changes can cause a protein to unravel and lose its shape. • This is called denaturation.
  39. 39. Proteins as Nutrients • Our bodies can make several amino acids. • Essential amino acids: amino acids our bodies cannot make, must obtain from food. • Complete proteins: contain all essential amino acids. • Animal proteins (meat) more likely to be complete than plant proteins. Plant proteins can be combined to make complete. (a) Lentils are high in lysine and low in valine. (b) Rice is low in lysine and high in valine. The side groups of lysine and valine are different. Lysine Valine Lysine Valine Figure 3.2
  40. 40. Lipids • Lipids are hydrophobic (water-fearing). • They do not mix with water. • Oil and vinegar salad dressing separates into layers. – Examples: fats, oils, steroids, wax, cholesterol, phospholipids Figure 2.14
  41. 41. Fats • Dietary fat consists largely of the molecule triglyceride. • Triglyceride is a combination of glycerol and three fatty acids.
  42. 42. Fats (cont’d) • Fats perform essential functions in the human body: • Energy storage • Cushioning • Insulation
  43. 43. Saturated vs Unsaturated Fats Saturated fat Unsaturated fat • Unsaturated fatty acids • Have less than the maximum number of hydrogens bonded to the carbons (ie they have double bonds). Greatest called polyunsaturated. • Saturated fatty acids • Have the maximum number of hydrogens bonded to the carbons. • If all three fatty acids in a fat are saturated, it is a saturated fat. If any are unsaturated, it is an unsaturated fat. Figure 3.4
  44. 44. Saturated vs Unsaturated Fats (cont’d) • Most animal fats have a high proportion of saturated fatty acids, which can be unhealthy. • Examples: butter, lard • Usually solid at room temperature • Contribute to atherosclerosis and cardiovascular disease • Most plant and fish oils tend to be low in saturated fatty acids. • Example: corn oil, canola oil, cod liver oil • Usually liquid at room temperature
  45. 45. Hydrogenation and Trans Fats • Hydrogenation: Conversion of unsaturated fats to saturated fats by adding hydrogen. • Production of margarine and peanut butter • Fats created by hydrogenation are unhealthy because trans fats are produced. – Trans fats: type of unsaturated fat (shortening, margarine) – Found in many fast food products, although now banned – No nutritional value – Increase risk of cardiovascular disease – Even more unhealthy than saturated fats.
  46. 46. Steroids • Another type of lipid. • Different from fats in structure and function. • Carbon skeleton is bent to form four fused rings. • Cholesterol is the “base steroid” from which your body produces other steroids. • Example: sex hormones (testosterone, estrogen)
  47. 47. Anabolic Steroids • Synthetic anabolic steroids are controversial. • They are variants of testosterone. – Some athletes use anabolic steroids to build up their muscles quickly. • However, these substances can pose serious health risks. • Mood swings • Depression • Liver damage • High cholesterol • Shrunken testicles, reduced sex drive, infertility
  48. 48. LIST OF REFERENCES Slides copied from the following sources on SlideShare: • 2- Chemistry of Life I by tchubb on Sep 08, 2011. Accessed: 08/03/2014. Slide no:18 • Molecules of life introby eruder on Sep 25, 2011. http :// Accessed: 08/03/2014. Slide no: 1-13 • 1 molecules of life by Justina, H on Sep 10, 2011. Accessed: 08/03/2014. Slide: 9, 10, and 22-29.
  49. 49. REFERENCE CONTINUE: • Lecture 4 molecules of life by holmeskm on May 27, 2011. qid=77969b92-9647-492c-95e1-b85acafadc30&v=default&b=&from_search=4. Accessed: 08/03/2014. Slide no: 1, and 9-32 • Water by Jaya Kumar, Lecturer at KDU College Sdn Bhd on Mar 08, 2012. Accessed: 08/03/2014