Question

Match Column-I with Column-Il and select the correct option from the codes given below. Column-I \(\quad\) Column-II A. TCA cycle (i) Inner mitochondrial membrane B. \(\mathrm{F}_{0}-\mathrm{F}_{1}\) particles (ii) Hans Krebs C. End product of (iii) Oxidative decarboxylation glycolysis D. Pyruvate (iv) Pyruvic acid dehydrogenase (a) \(\mathrm{A}\)-(ii), B-(i), C-(iv), D-(iii) (b) \(A-(i), B-(i i), C-(i v), D-(i i i)\) (c) \(\mathrm{A}-(\mathrm{ii}), \mathrm{B}-(\mathrm{iii}), \mathrm{C}-(\mathrm{iv}), \mathrm{D}-(\mathrm{i})\) (d) \(A\)-(iii), B-(ii), C-(i), D-(iv)

Short answer

The correct option is (a) A-(ii), B-(i), C-(iv), D-(iii).

Step-by-step solution

Identify the Correct Associations for Each Item in Column-I

Firstly, we need to correctly match each term in Column-I with its associated term in Column-II.A. TCA cycle is associated with Hans Krebs (ii), because it is also known as the Krebs cycle.B. \(\mathrm{F}_0-\mathrm{F}_1\) particles are located in the inner mitochondrial membrane (i), as they are part of the ATP synthase complex.C. The end product of glycolysis is pyruvic acid (iv), which is later converted to acetyl-CoA for entry into the TCA cycle.D. Pyruvate dehydrogenase (iv) is the enzyme that catalyzes the oxidative decarboxylation of pyruvate to acetyl-CoA.

Compare the Associations with the Given Options

After determining the correct associations, match them with the given options to find the correct one.A-(ii)B-(i)C-(iv)D-(iii)Option (a) matches the associations we found.

Key concepts

TCA Cycle

The Tricarboxylic Acid (TCA) cycle, also known as the Krebs cycle, is a critical metabolic pathway for energy production within our cells. It takes place in the mitochondria, the powerhouses of the cell, and involves a series of chemical reactions that break down acetyl-CoA, derived from carbohydrates, fats, and proteins into carbon dioxide and transfers energy through reducing power to the electron transport chain.

During the TCA cycle, electrons are transferred to NAD+ and FAD, forming NADH and FADH2, which are then used in the electron transport chain to generate a significant amount of ATP through oxidative phosphorylation. It is named after Hans Krebs, who was the first to elucidate the cycle's steps.

• Starts with the condensation of acetyl-CoA with oxaloacetate.
• Generates NADH and FADH2 for further energy production.
• Produces ATP or GTP directly through substrate-level phosphorylation.
• Releases carbon dioxide as a byproduct.

ATP Synthesis

ATP synthesis is the process by which cells generate adenosine triphosphate (ATP), the universal energy currency of the cell. This process is carried out by ATP synthase, an enzyme complex located in the inner mitochondrial membrane. ATP synthase has two main components: the F₀ unit which forms a channel that allows protons to flow across the mitochondrial membrane, and the F₁ unit which uses this proton flow to synthesize ATP from ADP and inorganic phosphate. This process is driven by the electrochemical gradient created by the electron transport chain.

• The energy for ATP synthesis comes from the proton motive force generated by the electron transport chain.
• Chemiosmosis is the mechanism by which ATP synthesis is coupled with electron transport.

Glycolysis

Glycolysis is the first stage of cellular respiration, a ten-step process that converts glucose into pyruvate, generating a small amount of energy in the form of ATP and NADH. It takes place in the cytoplasm of the cell and does not require oxygen, thus it can occur in both aerobic and anaerobic conditions.

Glycolysis begins with the investment of ATP to modify glucose and ends with the production of two molecules of pyruvate, two molecules of NADH, and a net gain of two ATP molecules through substrate-level phosphorylation. This metabolic pathway is crucial for cells as it provides intermediates for other processes and serves as the starting point for aerobic respiration when oxygen is available.

• Converts one molecule of glucose into two molecules of pyruvate.
• Generates net two ATP and two NADH per molecule of glucose.
• Occurs in the cytoplasm and serves as an anaerobic source of energy.

Pyruvate Dehydrogenase

The pyruvate dehydrogenase (PDH) complex is a crucial enzyme in cellular respiration, serving as a link between glycolysis and the TCA cycle. This enzyme catalyzes the oxidative decarboxylation of pyruvate, the end product of glycolysis, converting it into acetyl-CoA that can enter the TCA cycle. This reaction occurs in the mitochondrial matrix and involves the removal of a carboxyl group from pyruvate, releasing it as carbon dioxide.

The activity of PDH is tightly regulated through feedback inhibition by its products and by covalent modification, ensuring that energy production is adjusted according to cellular needs. This regulation ensures an efficient and balanced production of ATP in accordance with the cell's energy demands.

• Acts as a critical link between glycolysis and the TCA cycle.
• Regulated to match the cell's energy requirements.
• Generates acetyl-CoA for entry into the TCA cycle.