Summary H14 - Phys ch 3 + Zoo ch 30

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Summary - H14 - Phys ch 3 + Zoo ch 30

  • 1 -

  • What are anabolic and catabolic reactions?
    • Anabolic: involves the production of larger molecules from smaller reactants.
    • Catabolic: involves the breakdown of larger molecules into smaller molecules.
  • What is ATP and from what it synthesized?
    • A compound which serves a s a temporary energy storage
    • Synthesized from a nucleotide called adenosine diphosphate (ADP) and a phosphate (Pi). 
  • What type of reaction is ATP synthesis
    A condensation reaction but also a phosphorylation reaction because of addition of P.
    • ADP+P+energy = ATP + H2O
  • What is ATP hydrolysis?
    The breakdown of ATP.
    • ATP (+H2O) =ADP + Pi + energy 
  • Where do cells get the energy to synthesize ATP?
    From glucose oxidation because it has a negative energy change and it occurs spontaneous.
  • The oxidation of 1 mol glucose releases energy to make 98 mol ATP.
  • How many mol ATP can be synthesized from the energy of 1 mol glucose? Why is this?
    • 1 mol glucose releases energy to make 98 mol of ATP.
    • HOWEVER: only 38 mol of ATP is made in practice. This causes the net energy change to be negative and therefore the reaction can proceed in the forward direction, yielding ATP as a product. 
  • What are the 3 stages of glucose oxidation and where do the reactions take place?
    1. Glycolysis. Takes place in the cytosol.
    2. the Krebs cycle. Occurs in the mitochondrial matrix.
    3. Oxidative phosphorylation. Occurs across the inner mitochondrial membrane. 
  • What is glycolysis?
    The splitting of sugar. Each glucose molecule (containing 6C) is broken down into 2 pyruvate (containing 3C each).
  • What are the 3 major results of glycolysis?
    1. After glycolysis each glucose has broken down into 2 pyruvate molecules.
    2. 2 ATP molecules are consumed during glycolysis, but 4 ATP is produced, meaning a net synthesis of 2 ATP.
    3. 2 molecules of NAD+ are reduced, yielding 2 molecules of NADH for every molecule of glucose. 
  • 2 -

  • During glycolysis no oxygen is used and no carbondioxide is produced.
  • Why is glycolysis useful for cells?
    • Because it produces some ATP
    • Sets the stage for subsequent events that yield more ATP
    • NADH releases energy that will be used to synthesize ATP in oxidative phosphorylation
  • When oxygen is limited pyruvate is converted to lactic acid.
  • What is the "linking step" and where does this happen?
    The step between glycolysis and the Krebs cycle in which pyruvate is converted into acetyl CoA in the mitochondrial matrix.
  • What are the major results of the Krebs cycle?
    1. After each Krebs cycle 2 CO2 molecules have been generated as end products.
    2. Only 1 ATP is generated per Krebs cycle, and therefore 2 in total for each glucose molecule.
    3. In 1 cycle 4 co-enzymes are produced, namely 3 NADH and 1 FADH2.
  • How many Krebs cycles take place in the oxidation of 1 glucose molecule?
    2 because glycolysis yields 2 pyruvate molecules and therefor also 2 acetyl CoA molecules which leads to 2 Krebs cycles taking place.
  • Is there oxygen needed for the Krebs cycle?
    No, no oxygen is used for glucose oxidation so far.
  • Does oxygen play a role in glucose oxidation at all?
    Yes. It is very important in final step, oxidative phosphorylation, because oxygen is the ultimate acceptor of all the electrons that are given up by NADH + (H+) or FADH2. Without oxygen the electrons would have no where to go and oxidative phosphorylation would stop.
  • Of what 2 simultaneous processes does oxidative phosphorylation consist?
    1. The transport of H+ or electrons through a series of compounds in the inner mitochondrial membrane known as electron transport chain. It releases energy
    2. The harnessing of this energy to make ATP, which is done by a mechanism called chemiosmotic coupling
  •  By what enzyme is the synthesis of ATP catalyzed?
    By ATP synthase.
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What is ATP and from what it synthesized?
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