12.4 Anaerobic respiration Flashcards
What happens in the absence of oxygen
Neither the krebs cycle nor the electron transfer chain can continue because soon all the FAD and NAD will be reduced. No FAD or NAD will be available to take up the H+ produced during the krebs cycle and so the enzymes stop working
What must happen for glycolysis to continue
The products of pyruvate and hydrogen must be constantly removed
The hydrogen must be released from the reduced NAD in order to regenerate NAD. Without this, the already tiny supply of NAD in cells will be entirely converted to reduced NAD, leaving no NAD to take up the hydrogen newly produced from glycolysis
What are the two types of anaerobic respiration that occur in eukaryotic cells
- In plants, pyruvate is converted to ethanol and carbon dioxide
- In animals, pyruvate is converted to lactate
How is ethanol produced in plants during anaerobic respiration
The pyruvate molecule formed at the end of glycolysis loses a carbon dioxide molecule and accepts hydrogen from reduced NAD to produce ethanol
How is lactate produced in animals during anaerobic respiration
Each pyruvate molecule produced takes up two hydrogen atoms to form lactate. Lactate can be oxidised back to pyruvate however, requiring oxygen
What are the energy yields from anaerobic and aerobic respiration
Only glycolysis (2 molecules)
Why does the conversion of pyruvate into lactate allow the continued production of ATP during anaerobic respiration
The conversion of pyruvate to lactate involves the acceptance of hydrogen atoms from reduced NAD. The removal of these hydrogen atoms reforms NAD via oxidation which can then accept more hydrogen and continue glycolysis
What is an advantage of converting lactate back to pyruvate when supplied with oxygen
Lactate caused muscle fatigue so the conversion back to pyruvate prevents this
