At which one of the following electron transport chain complexes does Antimycin A typically inhibit the respiratory chain?
Complex III
The electron transport chain (ETC) is a series of protein complexes embedded in the inner mitochondrial membrane. It plays a crucial role in cellular respiration, generating ATP by creating a proton gradient across the membrane.
Antimycin A Inhibition
Specific molecules known as inhibitors can block the flow of electrons at certain points in the electron transport chain, disrupting the process of oxidative phosphorylation.
Antimycin A is a known inhibitor that affects the respiratory chain. It acts specifically on one of the major complexes within the ETC.
Complex III and Antimycin A
Antimycin A is recognized for its ability to block the transfer of electrons within Complex III. Complex III, also known as cytochrome bc1 complex, receives electrons from Complex I (via ubiquinone) and Complex II (via ubiquinone) and passes them to Complex IV (via cytochrome c).
By binding to Complex III, Antimycin A prevents the transfer of electrons from cytochrome b to cytochrome c1. This blockage stops the flow of electrons through Complex III and subsequently halts the entire downstream electron transport, including the activity of Complex IV.
The inhibition of Complex III by Antimycin A leads to:
- Accumulation of reduced ubiquinone.
- Prevention of proton pumping by Complex III.
- Disruption of the proton gradient used for ATP synthesis by ATP synthase.
- Reduced oxygen consumption by Complex IV.
Electron Transport Chain Overview
The main complexes of the electron transport chain are:
- Complex I: NADH-ubiquinone oxidoreductase
- Complex II: Succinate-ubiquinone oxidoreductase
- Complex III: Ubiquinone-cytochrome c oxidoreductase (cytochrome bc1 complex)
- Complex IV: Cytochrome c oxidase
Antimycin A's specific target is Complex III.
Important Questions from Photosynthesis
Kranz anatomy is found in _____ plant.
Which plant pigment is present in tomatoes?
Which one of the following reactions takes place during the reduction phase of the Calvin - Benson cycle?
The following statements were made with the assumption that the concentration of 3- phosphoglycerate is high inside chloroplasts of an actively photosynthesizing leaf.
A. There will be high concentration of triose phosphate in the chloroplast.
B. The activity of ADP-glucose pyrophosphorylase will be inhibited.
C. The carbon flow will be diverted from sucrose to starch.
D. Starch synthesis will be inhibited and carbon flow will be more towards sucrose synthesis.
Which one of the following combinations of above statements is correct?
The table below shows photosynthetic type, temperature and sunlight intensity levels.
Photosynthetic Type Temperature Sunlight Intensity A. C3 Plant i High P. High B. C4 plant ii Moderate Q. Moderate iii Low R Low Which of the following correctly matches the plant photosynthetic type with the temperature and sunlight conditions in which photosynthetic rate per unit leaf area is maximum for that plant?
