Problem 17 - Objective Biology for NEET

Question

At how many places in Kreb's cycle FADH \(_{2}\) is formed? (a) 1 (b) 2 (c) 3 (d) 4

Step-by-Step Solution

Answer

The FADH\(_2\) is formed once in Kreb's cycle, so option (a) 1 is the correct answer.

Step 1: Understanding Kreb's cycle and Role of FADH\(_2\)

The first step is to recall the process of the Kreb's cycle. FADH\(_{2}\) is formed in the step where FAD+ takes up two hydrogen atoms to form FADH\(_2\). This step occurs in the conversion of Succinate to Fumarate.

Step 2: Counting FADH\(_2\) formation in Kreb's cycle

The next step is to remember that in a single cycle, the formation of FADH\(_2\) happens once during the conversion of Succinate to Fumarate.

Step 3: Selecting the correct answer

Based on the knowledge of Kreb's cycle and the formation of FADH\(_2\), one can determine the correct answer. It is clear that the formation of FADH\(_2\) occurs once in a single turn of Kreb's cycle.

Key Concepts

FADH2 Formation

In the Krebs Cycle, also known as the Citric Acid Cycle, FADH\(_2\) plays a crucial role. This molecule is essential in the energy production process of the cell. FADH\(_2\) is created during one specific moment in the cycle. This occurs during the conversion of succinate to fumarate. Here, flavin adenine dinucleotide (FAD) acts as an electron acceptor.
It picks up two hydrogen atoms, becoming FADH\(_2\). This process is vital because it helps shuttle high-energy electrons to the electron transport chain.

• FADH\(_2\) formation occurs only once per cycle.
• It provides electrons for ATP production, helping generate energy efficiently.
• This adds to the body's overall energy yield.

The production of FADH\(_2\) is more than just a singular event; it is part of a larger energy-producing mechanism essential for cellular respiration.

Succinate to Fumarate Conversion

The conversion of succinate to fumarate is one of the key reactions within the Krebs Cycle. This transformation is facilitated by the enzyme succinate dehydrogenase. It is the only enzyme in the Krebs cycle that is also part of the electron transport chain.
This conversion involves the oxidation of succinate to form fumarate. During this reaction, FAD is reduced to FADH\(_2\).

• Succinate donates electrons to FAD, reducing it to FADH\(_2\).
• FADH\(_2\) captures and stores electrons for later use in the electron transport chain.
• This step is vital for maintaining the cycle's energy balance.

Beyond its role in forming FADH\(_2\), succinate's conversion is crucial for the continuing cycle of energy production and regeneration of oxaloacetate. This prepares it for a new cycle beginning.

Metabolic Pathways

Metabolic pathways, like the Krebs Cycle, are a series of chemical reactions that occur within a biological entity. These pathways sustain life processes by facilitating the production and breakdown of biomolecules. The Krebs Cycle is central to cell metabolism as it connects various metabolic pathways. It is a source of reducing agents like NADH and FADH\(_2\), which are crucial for ATP production.

• The Krebs Cycle is a link between carbohydrate, fat, and protein metabolism.
• It helps harness energy efficiently for cellular activities.
• It provides intermediates for biosynthetic processes.

Understanding these pathways is fundamental as they showcase the interconnectedness within cellular activities. The energy captured during these processes is vital for the organism's survival and efficiency.