1 / 15

Metabolism

Metabolism. Chemical Reactions. All chemical reactions involve the breaking and formation of chemical bonds which changes the arrangements of atoms and ions Dehydration reactions: removal of an –OH and an –H from two reactant molecules

edward-sargent
Download Presentation

Metabolism

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Metabolism

  2. Chemical Reactions • All chemical reactions involve the breaking and formation of chemical bonds which changes the arrangements of atoms and ions • Dehydration reactions: removal of an –OH and an –H from two reactant molecules • It is the most common method used by cells to join smaller molecules and assemble extremely large macromolecules (complex carbs and proteins)

  3. Hydrolysis – opposite of dehydration reaction, water is used as a reactant • Neutralization reactions – between acids and bases to create water and salts

  4. Redox Reactions • Electrons are lost from one atom and gained by another • Entire atoms may be transferred during a redox reaction • Oxidation results in an oxidized molecule or atom • The oxidizing agent is the molecule or atom behind reduced • The reducing agent is molecule or atom being oxidized • “oxidation” also refers to the transfer of entire hydrogen atoms (and their electrons) from less electronegative atoms to more electronegative atoms

  5. During oxidation reaction the electrons involved are more strongly attracted to the oxidizing agent. • Redox reactions involve electrons moving from where they are weakly held to where they are more strongly held. • Why reviewing redox? They are responsible for most of the energy transfer within cells

  6. Energy • Energy: • The capacity to do work • To change or move matter against an opposing force such as gravity or friction • Kinetic Energy: • energy of motion • Potential Energy: • stored energy, energy that is available but not yet released

  7. Energy and Chemical Bonds • Conversion of energy from one form to another depends on the breaking and reforming of chemical bonds • The amount of potential energy in a chemical reaction will change depending on the atoms/molecules involved • Potential energy of electrons depends on their location in relation to the nucleus • The further away electrons are from the nucleus the more potential energy they have • Potential energy of outer electrons increases when they absorb energy

  8. Energy Changes and Chemical Reactions • For bonds to break in reactants energy must be first absorbed (energy is required to pull an electron away from an atom) • When bonds are formed in products energy is released • Electrons lose potential energy as they get closer to the nucleus • Electron positions will change when bonds are reformed • The change in the potential energy of these electrons is what accounts for the change in energy during a chemical reaction • Released energy can be converted to different forms (thermal, light, vibrational or mechanical)

  9. Bond Energy • Measure of strength or stability of a covalent bond • Measured in units of kJ/mol) and is equal to the amount of energy absorbed per mol when the bond between atoms is broken. • Bond energy value is equal to the amount of energy released per mole when the same bonds form • The energy needed to break a bond reflects the relative strength of the bond • Example – it takes 799kj/mol to break a double bond between oxygen and carbon but 411kJ/mol to break a bond between C and H – therefore twice as much energy is released when C=O bonds form

  10. Activiation energy: the minimum amount of energy that chemical reactans must abosrb to start a reaction (EA) • Transition state: temporary condition during a chemical reaction in which the bonds in the reactants are breaking and the bonds in the products are forming • Exothermic reaction: chemical reaction in which energy is released, leaving the products with less chemical potential energy than the reactants • Endothermic reaction: a chemical reaction in which energy is absorbed, giving the products more chemical potential energy than the reactants

  11. Average Bond Energies

  12. Tutorial questions PRACTICE QUESTION

  13. Electron Carriers • Electrons that pass from one atom to another carry energy with them. • Reduced form of a molecule is always at a higher energy level than the oxidized form • Electrons are said to have reducing power • Electron Carriers - compounds that pick up electrons from energy rich compounds and then donate them to low energy compounds (they are the Robin Hoods of our molecules)

  14. Electron Carriers • NAD+ (nicotinamide adenine dinucleotide) • FAD (flavin adenine dinucleotide) • NAD+ and FAD are the oxidized form • NADH and FADH2 are the reduced forms

More Related