MODULE 11: Chapter 10.4 Flashcards
What is the main end product of the citrate cycle?
Oxaloacetate
What are the three main control points within the citrate cycle?
- Citrate synthase (reaction 1)
- Isocitrate dehydrogenase (reaction 3)
- α-ketoglutarate dehydrogenase (reaction 4)
How is pyruvate dehydrogenase activity regulated?
By metabolites that signal the energy charge in the cell
What activates pyruvate carboxylase allosterically?
Acetyl-CoA
What inhibits citrate synthase?
- High NADH-to-NAD⁺ ratios
- NADH
- ATP
- Succinyl-CoA
- Citrate
True or False: Increased ADP levels activate citrate synthase.
True
What stimulates the activity of pyruvate dehydrogenase, isocitrate dehydrogenase, and α-ketoglutarate dehydrogenase?
Ca2⁺
What was the breakthrough discovery in 1917 regarding citric acid production?
Large amounts of citric acid could be isolated from the mold Aspergillus niger
What conditions are optimized to produce citrate in Aspergillus?
Maintaining a constant biomass and selecting for high-capacity citrate export strains
What does the fermentation process using Aspergillus convert sucrose into?
Citrate
What are the two types of feedback inhibition in the citrate cycle?
- Product inhibition
- Metabolite inhibition by ATP
Fill in the blank: Citrate synthase is inhibited by _______.
Citrate
What is a key regulatory strategy to prevent unnecessary reactions in the citrate cycle?
Regulation by ATP ensures low enzyme activity when energy is sufficient
How much citric acid is produced annually from fermentation methods?
Nearly 500,000 metric tons
What is the efficiency of the overall reaction in optimized fermentation cultures of Aspergillus?
About 75%
What must be maintained in the culture system to ensure citrate production despite CO2 production?
Carbon flow must be maintained
What is the role of citrate in commercial applications?
- Preservation of processed foods
- Reactive acid in polymer chemistry
- Stabilizer in pharmaceuticals
