Biological Molecules ( I and a group of friends )


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Biology projectwork.please download to view more efficiently because there are A LOT of transitions and animations to consider before viewing ( it looks like pictures rest on the text because the text flies onto the screen, moves away and the pictures fall in )

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Biological Molecules ( I and a group of friends )

  1. 1. BIOLOGICAL MOLECULES Carbohydrates, fats , proteins and water 1
  2. 2. CARBOHYDRATES  Carbohydrates are a large group of organic compounds occurring in foods and living tissues and including sugars, starch, and cellulose.  They contain carbon, hydrogen and oxygen.  hydrogen and oxygen are in the same ratio as water (2:1) and typically can be broken down to release energy in the animal body.  They  It have a general formula Cx(H2O)y. is divided into 3 main groups: Monosaccharides, Disaccharides and Polysaccharides. 2
  3. 3.  Monosaccharaides are sugars which dissolve easily in water to form a sweet solution.  They are single sugars (mono)  They have the formula (CH2O)n where n is an integer.  The are classified according to the number of carbon atoms in each molecule. Example Triose has 3 carbon atoms.  All sugars end in -ose MONOSACCHARIDE 3
  4. 4. Monosaccharides can be represented in straight form or ring form. Its role in living organisms is to: provide a source of energy in respiration Serve as building blocks for larger molecules (starch) STRUCTURES AND FUNCTIONS 4
  5. 5. DISACCHARIDES  These are any of a class of sugars whose molecules contain two monosaccharide.  When two monosaccharides bond they form a glycosidic bond through a condensation reaction.  Hydrolysis is the reverse of the condensation reaction and forms two monosaccharides from one disaccharide. 5
  6. 6. POLYSACCHARIDES It is a carbohydrate whose molecules consist of a number of sugar molecules bonded together by a glycosidic bond. They are not sugars because they are insoluble. In animals polysaccharides are glucose and in plants starch. The most common polysaccharide is cellulose. 6
  7. 7.  Starch  They and glycogen are very similar. are both made up of amylose and amylopectins.  Amylose is made of many alpha-glucose molecules bonded together forming 1,4 linked glucose molecules, the chains are curved and coil into a helical structure.  Amylopectin is also made up of 1,4 linked glucose molecules but also has branches formed by1,6 linkages.  The difference between starch and glycogen is that glycogen have more branches than that of starch. STARCH AND GLYCOGEN 7
  8. 8. Cellulose It makes up the cell wall of a plant cell. is a polymer of beta-glucose In order for a glycosidic bond to be formed in beta-glucose must be rotated. This makes cellulose a strong molecule because of its hydrogen bonds. CELLULOSE 8
  9. 9. TESTING FOR THE PRESENCE OF REDUCING SUGARS  Benedict's reagent (copper(II) sulphate) is used to test for the presence of sugars. It has a blue colour and only reacts in alkaline conditions.  The benedict's solution must be added in excess to the sample being tested and heated in a water bath. A positive test will cause the solution to turn from blue to green to yellow to orange and finally brick-red.  All monosaccharides and disaccharides have this effect on benedict's because they are reducing sugars. 9
  10. 10. TESTING FOR THE PRESENCE OF NON-REDUCING SUGARS  Some disaccharides are non-reducing hence Benedict's will have no effect on it.  The sample sugar must be heated with hydrochloric acid (HCl) in order to break the glycosidic bonds.  The solution must then be neutralised with sodium hydroxide before the benedict’s solution can be added and heated.  If there is a sugar present the solution will change colour if not there will be no colour change hence no sugar is 10 present.
  11. 11. TESTING FOR THE PRESENCE OF STARCH The spiralled shape of starch molecules allows just enough space for iodine molecules. Therefore iodine solution (potassium iodide solution) can be used to test for the presence of starch. Iodine solution is orange-brown in colour and when added to a solution containing starch turns blue- 11 black.
  12. 12. Lipids are a group of chemicals. The most common type are the triglycerides, which are commonly known as fats and oils. Fats are solids at room temperature whereas oils are liquid. Also fats are found in animals whiles oils are found in plants. Their solid and liquid states arise from the saturated nature of fats and the unsaturated nature of oils. The unit structures of fats are fatty acids and glycerol LIPIDS
  13. 13.  Triglycerides are made by the combinationof 3 fatty acid molecules with one glycerol molecule. The longer the chain of fatty acids, the more energy can be released during oxidation. Double bonds in the fatty acids caus ea kink in the chain which determines if it is is saturated on unsaturated. TRIGLYCERIDES
  14. 14. Each molecule has the unusual property of one end hydrophilic and one end hydrophobic ; this is because the glycerol head has a phosphate group embedded in to and the three fatty acids are replaced by two instead PHOSPHOLIPIDS
  15. 15. Amino acids are the unit structures of proteins. Linking these structures are peptide bonds . During this linkage, water is lost by condensation to form dipeptides and finally polypeptides. THE AMINO ACID
  16. 16. Primary structure: it shows the sequence in which amino acids are joined. Secondary structure: due to the effect polypeptide chains have each other, the polypeptide chain usually coils into an alpha helix or beta pleated sheet ( hydrogen bonds occur when –CO group of one amino acid is attracted to the –NH group of the other amino acid 4 places ahead of it) Tertiary structure: the precise way in which the secondary structure is coiled into a 3d figure is the tertiary structure Quaternary Structure: the quaternary structure is made up of two or more tertiary structures, it is the association of polypeptide chains POLYPEPTIDE STRUCTURE
  17. 17. Denaturation occurs when the WHAT HOLDS A PROTEIN bonds holding the shape of a protein are broken. If the protein is soluble, MOLECULE TOGETHER? the protein renders it insoluble. Extreme pHs break ionic bonds by altering the charges on the R groups  Hydrogen Bonds :broken by high Reducing agents break disulfide temperatures or pH changes bonds which can be seen in perming  Disulphide Bonds : formed by two hair. cysteine molecules , bonds can be Globular proteins are more broken by reducing agents susceptible to denaturation the fibrous proteins, this could be  Ionic Bonds: formed between amine and carboxylic acid groups, bonds can because fibrous proteins have more disulphide bonds holding them be broken by pH changes. together, it could also be because  Hydrophobic interactions also occur fibrous proteins are mostly found between hydrophobic side chains outside the cell where temperature is not as easily controlled.
  18. 18. ADDITIONAL INFORMATION Gel electrophoresis using size and using pH Collagen and Haemoglobin: haemoglobin is made up of four polypeptide chains, two identical alpha chains and 2 identical beta chains; therefore in each haemoglobinn molecule, four haem groups carry four oxygen molecules.
  19. 19.  Water is a dipole. Because hydrogen and oxygen atoms are different in size and electronegativity, the water molecule is non-linear and polar. polarity means that individual water molecules can form hydrogen bonds with other water molecules Although these individual hydrogen bonds are weak, collectively they make water a very Hydroge n atom stable substance. Hydroge n atom  This WATER: THE LIFE MOLECULE Oxygen atom Hydroge n atom Oxygen atom Hydroge n atom
  20. 20.  Solvent properties: the polarity of water makes it an excellent solvent. The electrostatic attractions between polar water molecules and ions of a solute are stronger than those between the cations and anions of the solute.  High specific heat capacity: lots of energy needed to break hydrogen bonds.  High latent heat of vaporization: hydrogen bonds attract molecules of liquid water to one another and make it difficult for the molecules to escape as vapor.  Molecular mobility: the weakness of individual hydrogen bonds means the individual water molecules mobile.  Cohesion and surface tension: hydrogen bonding causes water molecules to stick together, and also stick onto other molecules causing cohesion. This results in surface tension. PHYSICAL PROPERTIES
  21. 21. IMPORTANCE OF WATER  Solvent properties allow water to act as a transport medium for polar solutes: movements of minerals to lakes and seas, transport via blood and lymph in multicellular animals, etc.  Cohesion between water molecules create the continuous column of water in transpiration streams.  Molecular mobility allows water molecules to move easily relative to one another-this allows osmosis to take place.  Expansion on freezing allows ice to float and insulates organisms in the water below it.  Water can be used directly as a reagent in photosynthesis, to hydrolyze macromolecules to their subunits in digestion and is also the medium in which all biochemical reactions take place.
  22. 22. IMPORTANCE CONTINUED  Volatility is balanced at the Earth’s temperatures so that a water cycle of evaporation, transpiration and precipitation is maintained.  Water’s cohesive and adhesive properties mean that it is viscous, making it a useful lubricant in biological processes:  Synovial fluid: lubricates vertebrate joints  Pleural fluid: minimizes friction between lungs and thoracic cage during breathing  Mucus: permits easy passage of feces down the colon and lubricates the penis and vagina during sexual intercourse.  The high specific heat capacity of water means that bodies composed largely of water are very thermostable and thus less prone to heat damage by changes in environmental temperatures.  The high latent heat of vaporization of water means that body can be considerably cooled with a minimal loss of water. This can be seen in sweating, gaping in mammals and transpiring leaves.