Problem 90 - Objective Biology for NEET

Question

Which of the following element is a component of ferredoxin? (a) \(\mathrm{Cu}\) (b) \(\mathrm{Mn}\) (c) \(\mathrm{Zn}\) (d) \(\mathrm{Fe}\)

Step-by-Step Solution

Answer

The element which is a component of ferredoxin is Iron, symbolized as \( \mathrm{Fe} \).

Step 1: Identify the Key Information

From the name, it can be inferred that ferredoxin is related to Iron as 'ferr-' is a prefix often used to denote iron content. Thus, it is possible the component of ferredoxin among the options is Iron.

Step 2: Confirm Your Hypothesis

To confirm this, look up the composition of ferredoxin in a reliable biochemical reference text or database. You'll find that indeed, ferredoxins are iron-sulphur proteins, containing clusters of iron and sulphur atoms. The iron atoms are key to the protein's ability to transfer electrons and carry out its metabolic functions.

Key Concepts

Iron-sulphur proteins

Iron-sulphur proteins are fascinating because they incorporate iron and sulphur atoms in their structure to form clusters. These proteins are vital for many cellular processes.
They can contain clusters like [Fe-S], [Fe3-S4], or [Fe4-S4], which vary in the number of iron and sulphur atoms.

• **Iron Atoms**: Iron is central in facilitating the versatile functions of these proteins, helping in binding and transferring electrons.
• **Sulphur Atoms**: Sulphur helps in stabilizing the iron atoms in their precise positions within the clusters.

These clusters are not only structural but functional too. They provide the framework that allows the proteins to accept and donate electrons, making them integral to biochemical pathways. Understanding their molecular structure is crucial for comprehending their function in biology.

Electron transfer

Electron transfer is a fundamental process in many biological systems. Iron-sulphur proteins like ferredoxin are excellent electron carriers.
This capability is due to the multiple oxidation states the iron atoms can exhibit, allowing them to act as efficient conduits for electrons in redox reactions.
**Mechanism of Electron Transfer**:

• **Acceptance of Electrons**: When a molecule donates electrons, the iron-sulphur cluster in the protein accepts them.
• **Transport within Protein**: The electrons move through the cluster, facilitated by the arrangement of iron and sulphur atoms.
• **Donation to Target Molecule**: Subsequently, the protein transfers the electrons to a nearby electron acceptor molecule, completing the transfer.

This electron transit is crucial in metabolic processes like respiration and photosynthesis, enabling energy production and molecular rearrangement indispensable for life.

Metabolic functions

The metabolic functions of ferredoxin are varied and critical to cellular survival.
They act as intermediates in many important processes, primarily due to their ability to transfer electrons.
**Key Roles in Metabolism**:

• **Photosynthesis**: In plant cells, ferredoxin transfers electrons during the light-dependent reactions, crucial for the conversion of light energy into chemical energy.
• **Respiration**: Ferredoxin is involved in electron transfer during respiration, helping to derive energy from nutrients.
• **Nitrogen Fixation**: In some bacteria, ferredoxin aids in reducing nitrogen molecules to amonia, a form plants can assimilate.

Its role in bridging the flow of electrons in these pathways badges ferredoxin and similar proteins indispensable for proper cellular function, showcasing their versatility and importance.