Below is a list of membrane components with reduction potent

Below is a list of membrane components (with reduction potentials) that could potentially be involved in an electron transport system for uranium reduction. Your job is to decide which components are needed to build an Electron Transport System for a bacterium that makes ATP by the anaerobic respiration of H2 and uranium. Your BFF thinks these electron transport systems (ETS) would work. For each ETS, give the reason that It is not suitable for this respiration process.

Solution

In anaerobic electron transport system mentioned in the given question, Uranium acts as a terminal electron acceptor unlike oxygen of aerobic electron transport chain. Bacteria are able to couple anaerobic respiration with the synthesis of ATP via the electron transport chain and the components of this process are located on the cytoplasmic membrane. For the successful utilization of electron accepting substrate and ATP generation, an electrochemical gradient must be established and requires three main criteria:

From the given list of probable electron transport chain components, we can select the ones according to their given E^\' o values. This value reflects the redox potential and is consistent with their tendency to deliver electrons.(More negative E\'o value means greater tendency to deliver electron and positive E\'o value means tendency to accept electrons)

A. For bacteria growing anaerobically, the components of ETS must be as follows ( in order)

1. Dehydrogenase (hydrogenase), 2. Quinone carrier and proton pump, 3. Cytochrome electron carrier, 4. Terminal reductases

In the given two figures of ETS, anaerobic respiration is not possible:

(i) Terminal reductase not present.

(ii) Quinone proton pump and terminal reductase not present