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ENZYMES

ENZYMES. College Prep Biology Mr. Martino. Energy: the capacity to perform work Energy makes change possible All organisms require it 2 forms: 1. Kinetic energy: energy of motion Moving mass of matter performs work by transferring its motion to other matter

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ENZYMES

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  1. ENZYMES College Prep Biology Mr. Martino

  2. Energy: the capacity to perform work Energy makes change possible All organisms require it 2 forms: 1. Kinetic energy: energy of motion Moving mass of matter performs work by transferring its motion to other matter Ex. Heat and light 2.Potential Energy: stored energy – capacity to do work Result of location or arrangement of matter Chemical Energy: potential energy of molecules - the most important type of energy for life ATP Energy and Organization of Life

  3. 1st Law of Thermodynamics: (Law of E conservation) total amount of E in universe is constant. • E cannot be created or destroyed • E can be transferred or transformed • 2nd Law of Thermodynamics: E conversions reduce the order of the universe • Increases the amount of disorder in a system (entropy) • Energy input is necessary to maintain organization

  4. Doing Cellular Work • Two main types of chemical reactions: • 1. Endergonic: requires a net input of E • Energy is absorbed from surroundings as rxn occurs • Products are rich in potential energy • Ex. photosynthesis

  5. 2. Exergonic: releases energy • Bonds of reactants contain more E than bonds in products • Remainder of the E is released to surroundings during reaction • Ex. Wood is burning or cellular respiration: breakdown of glucose and the storage of a usable form of E

  6. ATP : (Adenosine triphosphate) cell’s energy molecule • powers nearly all forms of cellular work • 3 parts connected by covalent bonds: • adenine, ribose, and a chain of 3 phosphate groups • nucleotide

  7. Bond between 2nd & 3rd P-group is unstable • Easily broken by hydrolysis • Break bond & 3 things occur: • P is removed • ATP becomes ADP (adenosine diphosphate) • E is released • An exergonic rxn which can be coupled with an endergonic rxn • Phosphorylation: the transfer of a P-group to a molecule • Most cellular work depends on ATP energizing other molecules by phosphorylation

  8. Enzyme Structure and Function • ATP’s E is immediately available when needed • Energy of Activation (Ea): amount of E reactants must absorb to start a chemical rxn • In ATP – Ea is the amount of E needed to break the bond between the 2nd and 3rd P group

  9. Enzymes: protein molecules that serve as biological catalysts • Enzymes have a unique 3-D shape • Each enzyme recognizes only specific substrates • Substrate: the substance an enzyme works on • Active site: small part of enzyme that binds to substrate • Enzymes are specific because its active site fits only 1 kind of substrate

  10. Important characteristics of enzymes: • Cannot make anything happen that could not happen on own • Increase rate of reaction hundreds to millions of times • Are not changed during reaction • Lowers the barrier Ea • Reusable • Work in forward and reverse • Very specific for substrate • Essential to life

  11. 5.4 Factors Influencing Enzyme Activity • Temperature - a measure of molecular motion • Temp. increases the rate of substrates colliding with active sites • If too low, substrates and active sites won’t connect • If too high, the increase molecular motion will break bonds holding enzyme into 3-D shape • People die if temperature reaches 112 F

  12. pH: measure of the concentration of H+ • Most all enzymes need a pH of 6-8 • pH changes denature enzymes • Ion concentration • Ions can disrupt the enzyme maintaining its shape • Ex. salt

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