Biochemistry-TCA Cycle

Biochemistry

Tca Cycle




Compiled By Simon Mwangi
Edition: 2024/25

, Science | Biochemistry I of IV pages
1. Where does the TCA cycle occur?
All reactions occur in mitochondria

2. What are the products of the TCA cycle?
NADH
FADH2 -> ETC (ATP)
GTP
CO2

3. What is Citrate synthesised from?
Acetyl CoA (2C)
- Oxaloacetate (4C)

4. What enzyme synthesises citrate?
Citrate Synthase

5. What can inhibit citrate synthase?
ATP

6. What does citrate inhibit?
PFK1

7. What does citrate activate?
ACoA carboxylase (fatty acid synthesis)

8. What is used for gluconeogenesis in the fasting state?
Oxaloacetate
this lowers the amount able to be used for TCA cycle

9. How is ketone synthesis triggered in the fasting state?
Oxaloacetate used for gluconeogenesis

Less acetyl coA used for TCA cycle, build up
Excess acetyl coA converted into ketones

10. What is isocitrate to citrate?
An isomer

11. What enzyme converts citrate to isocitrate?
Aconitase

12. What does fluoroacetate (rat poison) inhibit?
Aconitase
- Citrate -> Isocitrate

13. What is the rate-limiting step of the TCA cycle?
Isocitrate -> Co2 NADH-> Alpha-ketoglutarate (Enzyme: Isocitrate Dehydrogenase)


Biochemistry 2024/25 Edition