Enzymes and Nucleic acids recap-AS Biology [JM]


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Aim: explore and the structure and function of enzymes

List the main properties of enzymes
Explain the terms active site, specificity and catalysts
Discuss how enzyme activity is affected by temperature and pH

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  • 25,000 to 35,000 genes, which carry information that go toward determining your traits
  • Enzymes and Nucleic acids recap-AS Biology [JM]

    1. 1. Jorge Melo
    2. 2. Phosphate Group O 5 Nitrogenous base O=P-O CH2 (A, G, C, or T) O O N C4 Sugar (deoxyribose) C1 C3 C2
    3. 3. 5 O 3 3 OP 5 P 5 O 1 G C 3 2 4 4 2 1 3 5 OP P 5 T A 3 O O 5P 3 P
    4. 4.  Double helix Antiparallel (5’-3’) (3’-5’) Complementary rule Chargaff’s rule A-T C-G Hydrogen bonds
    5. 5.  The sugars Uracil instead of thymine RNA –usually single stranded
    6. 6.  mRNA  rRNA  tRNA
    7. 7.  DNA double helix unwind (helicase) RNA polymerase Ligase
    8. 8.  Helicase  RNATranscription polymer ase  Ligase Translation  tRNA
    9. 9.  Name given to some stretches of DNA and RNA that encode for a peptide Stands for: Ribonucleic acid
    10. 10.  I am important to life I am affected by temperature I am a globular molecule I am involved in biochemical reactions I am involved in the breakdown of molecules I am an Enzyme
    11. 11.  Aim: explore and the structure and function of enzymes Objectives:  List the main properties of enzymes  Explain the terms active site, specificity and catalysts  Discuss how enzyme activity is affected by temperature and pH
    12. 12.  Enzymes: facts and functions Enzymes: chemical structure Enzymes: properties Names of enzymes How enzyme works (theories) Activation energy and Rate of reaction The effect of temperature and pH on the enzyme
    13. 13.  Enzymes are chemicals that control the reactions in cells. They are the caretakers of cells and tissues. They make sure that cell chemistry is kept in good shape. Each one has a particular job to do.
    14. 14.  Clear the fat out the blood stream after a meal Detection of glucose level in the body Break down the alcohol in beer or wine (liver)
    15. 15.  Thousands of chemical reactions take place in the body every second. These make up the metabolism. Enzymes control the metabolism by determining when and how chemical reactions take place.
    16. 16.  Enzymes are catalysts that speed up the rate of metabolic reactions. These reactions will take place without enzymes, but they would take years rather milliseconds.
    17. 17.  Which of the following reactions break molecules down and which build molecules up? A glycogen molecule formed from glucose molecules. The digestion of starch to maltose. Urea formed from ammonia and carbon dioxide.
    18. 18.  Example of a reaction that you already know: Enzyme Enzyme Hydrolysis Condensation
    19. 19.  globular proteins. long chains of amino acids. In a globular protein, the amino acid chain is folded and wound into a spherical or globular shape.
    20. 20. EnzymeTertiarystructure
    21. 21.  Specific three-dimension shape (tertiary structure)  This is Important: if it is altered , the enzyme cannot function Three dimension shape is maintained by hydrogen bonds and ionic forces
    22. 22.  Specific. Not used up in reactions. Combine to form enzyme/substrate complexes. Only small amount of enzyme needed
    23. 23.  Are fast acting – high turnover number. Affected by temperature and pH. Some only able to work if a cofactor is present. Can be slowed down or stopped by inhibitors.
    24. 24.  Each enzyme can only catalyse one particular reaction. This is because an enzyme can only react with a specific substrate molecule. Amylase can only catalyse the hydrolysis of starch into smaller disaccharide maltose molecules. This is because amylase can only react with starch molecules.
    25. 25.  An enzyme acts on a chemical known as a substrate and the new substance that is formed is the product Enzyme Substrate product The name of the enzyme often comes from substituting or adding -ase in the name of the substrate
    26. 26.  The name of an enzyme comes from the particular substance on which it acts. Lactase acts on the milk sugar lactose. Amylase works on starch – proper name amylose. Cellulase breaks down cellulose.
    27. 27. Enzyme Substrate Reaction catalysedMaltase Maltose Hydrolysis of maltose to glucoseAmylase Amylose Hydrolysis of starch to maltoseAlcohol Alcohol Removal of hydrogendehydrogenase from alcoholDNA Ligase DNA Joining together 2 DNA strandsRNA polymerase Nucleotides that make Synthesis of mRNA to RNA DNA moleculeGlycogen synthetase Glucose Polymerisation of glucose into glycogenATPase ATP Synthesis or splitting of ATP
    28. 28.  Which substrate do you think each of these enzymes acts upon? Sucrase. Lipase. Protease.
    29. 29.  There are two models that explain how enzymes work:  1. Lock and Key theory  2. Induced fit theory
    30. 30. Substrate Products Enzyme Substrate complexActivationsite Enzyme Enzyme
    31. 31.  This attempts to explain why enzymes are specific. They are large molecules, usually much bigger than their substrates. Only a relatively small part comes into contact with the substrate.
    32. 32.  This is called the active site. Only 3-12 aa make the active site, but its shape is an exact fit for the substrate. The substrate is the key that fits the enzymes lock.
    33. 33.  The two molecules form a temporary structure called an enzyme/substrate complex The products are formed at the active site They then no longer fit and are repelled The active site is then free to react with more substrate
    34. 34. Catabolic reaction: certain enzyme break a substrate down into two or more products Enzyme Substrate ProductsEnzyme
    35. 35. Anabolic reaction: certain enzyme bond tow or more substrates together to assemble one product Substrates Enzyme ProductEnzyme
    36. 36.  The active site is a cavity of a particular shape Initially the active site is not the correct shape in which to fit the substrate As the substrate approaches the active site, the site changes and this results in it being a perfect fit After the reaction has taken place, and the products have gone, the active site returns to its normal shape
    37. 37.  Most reactions in cells would be very slow without enzymes. The substrate may not be converted into the product unless it is given extra energy. Heating the particles would increases their kinetic energy and they move about more quickly.
    38. 38.  This means that there is greater chance of collisions. The rate of reaction then increases.
    39. 39. The energy needed tostart a chemical reactionIt can be thought of as anenergy barrier to get overbefore the reaction can getunderway.This energy can besupplied in the form ofheat.But this is not practical inliving systems.
    40. 40.  By lowering the activation energy of a reaction, the enzyme provides a different pathway for the reaction. By lowering the activation energy, enzymes reduce the input of energy needed. This allows reactions to take place at the at the lower temperatures found in the cells of organisms.
    41. 41.  The factors that affect enzyme activity also affect the functions of the cell and ultimately the organism enzymes are proteins and their functions is therefore altered by:  Temperature  pH  Substrate concentration  Enzyme concentration  Cofactors  inhibitors
    42. 42.  Work in pairs and think about how are the enzymes affected with the temperature and pH
    43. 43.  High temp. reactions tend to take place faster (more kinetic energy) However if temp. is too high the enzyme may lose their shape  Bonds that old the tertiary structure of the enzyme molecule on shape tend to break  When the active site of the enzyme loses its shape it is no longer able to bond to the substrate  Enzyme denatured  Irreversible reaction
    44. 44.  The temperature at which the enzyme works most rapidly is called optimum temperature OT for plant enzymes  25 C OT for Human body  37 and 40 C OT some bacteria  80 C
    45. 45.  Can have a direct effect on the bonding responsible for holding the enzyme molecule in its precise three-dimensional shape. If the active site is changed then enzyme action will be affected Each enzyme has an optimum pH Extremes of pH can denature enzymes and stop them from functioning as catalysts
    46. 46.  Six facts about enzymes Enzymes are globular proteins They reduce the activation energy needed for a reaction to proceed and produce products Enzymes have a region called an active site. The site is the "lock" into which a substrate "key" fits. The enzyme then fits closely around the substrates. This is called induced fit. Enzyme activity is affected by substrate type, temperature, pH and substrate concentration.