HL 1 Biology

3.7a Anaerobic Respiration

<<Cell Respiration>>

Cell Respiration: the controlled release of energy from organic compounds to form ATP

  • Cells require energy for:
    • Synthesizing large molecules  (DNA, RNA + proteins)
    • Pumping molecules/ions across membranes (by active transport)
    • Moving things around inside the cell  (chromosomes, vesicles, protein fibre in muscle cells that cause muscle contraction)
  • ATP (Adenosine triphosphate)
    • When ATP splits into ADP & phosphate = energy is released
    • cannot be absorbed through plasma membrane
    • Organic compounds: have enzymes that break down energy, carefully so much of the energy released can be used to form ATP from ADP & phosphate

<<Glycolysis and Anaerobic Cell Respiration>>

  • Cell Respiration- can release energy from various organic compounds; carbohydrates/lipids usual substrates
  • when carbohydrates (like glucose) are used, most organisms begin cell respiration the same way

Glycolysis: a chain of reactions taking place in the cytoplasm of cells, which converts the glucose into a substance called pyruvate

  • no oxygen used
  • small amount of ATP is produced
  • *if no oxygen is available, this is the only ATP that can be produced in cell respiration

Process of glycolysis: (takes place in the cytosol)
  1. 6-carbon glycolysis: takes place in cytoplasm
  2. phosphorylation: glucose is reduced with the addition of 2 ATP
  3. lysis: glucose is split into two 3-carbon molecules
  4. oxidation: glucose is oxidized to pyruvate; NAD+ is reduced to NADH+ H+
  5. ATP formation: energy released from glucose produce 4 ATP
  6. Net gain: 2 ATP, 2 NADH+ H+, 2 pyruvate

Anaerobic conditions: glycolysis can only continue if the pyruvate is converted into other substances

  • in humans: pyruvate is converted into  lactate (lactic acid)
  • in yeast cells: pyruvate into ethanol (alcohol) and carbon dioxide
  • *substances are toxic in excess= must be removed from cells that produce them/be produced in limited quantities

Summary equations

  • glucose –> pyruvate  = occurs in most organisms, in aerobic/anaerobic cell respiration
  • pyruvate –> lactate = occurs in humans/some bacteria in anaerobic cell respiration
  • pyruvate –> ethanol + CO2 = occurs in yeast in anaerobic cell respiration

=============================DBQ=================================

Production and Consumption of ATP (p.89)

1 (a) dm3

(b) kg, g

2 (a) 18.25 kg ATP/134.4dm3 = 0.1358 kg dm-3

(b) 

3) It is possible to synthesize such large masses of ATP during races because only the glucose and oxygen is needed to be taken in and consumption of large amounts of ADP and phosphate is not required enabling the ATP to be synthesizes into large quantities. ATP is also produced through a cycle and thus could continue to process the synthesis over and over again. The synthesis of ATP is repeated phosphorylation of similar ADP molecules as well, which provide large masses of ATP to synthesize.

4) During the 100m race, this involves anaerobic activity during the production of ATP. Through this race, the ATP is being produced in exchange to the lack of oxygen consumed. This is processed through anaerobic activity through a chain reaction of glycolysis. As the ATP splits into ADP and phosphate, energy is released.

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One thought on “3.7a Anaerobic Respiration

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