Question

Name the 5c compound present in kreb's cycle​

Answer 1

Answer:

The 5 C compund present in Kreb's cycle is α - ketoglutarate.

Explanation:

Kreb's cycle:

• The Kreb's cycle is also called as the citric acid cycle.
• This cycle was discovered by Sir Hans Kreb in 1937.
• In eukaryotic orgaisms, Kreb's cycle takes place in the mitochondrial matrix. In prokaryotic organisms it takes place in cytoplasm.
• Kreb's cycle acts as an amphibolic pathway beacuse it serves as both catabolic and anabolic pathway.
• It involves 8 steps to oxidise 2 molecules of acetyl Co - A.
• The products of Kreb's cycle are ATP, NADH + H⁺, FADH₂, CO₂ and H₂O.

Steps in Kreb's cycle:

Step 1 :  Acetyl Co A is converted to citric acid by the help of the enzyme citrate synthetase. Oxaloacetate displaces the coenzyme and attatches to the acetyl group of Co- A.

Step 2 : A molecule of water is removed and then added back to citrate. This results in the conversion of citric acid to its isomer isocitric acid which is catalysed by the enzyme isomerase. This reaction is inhibited by fluoroacetate.

Step 3: Isocitric acid undergoes dehydrogenation and decarboxylation to form a 5 carbon compound α - ketoglutaric acid catalysed by the enzyme isocitric dehydrogenase.

Step 4 : α - ketoglutaric acid undergoes dehyrogenation and decarboxylation to form succinyl coenzyme A. This reaction is catalyzed by a multienzyme complex α - ketoglutarate dehydrogenase.

Step 5 : Succinyl coenzyme A gets converted to succinic acid which is catalysed by the enzyme succinyl kinase. Substrate level phosphorylation occurs in this step. The phosphate group displaces Co - A which is transferred to GDP to form GTP.

Step 6: In this step, succinic acid gets converted to funaric acid with the help of the enzyme succinate dehydrogenase. This is an oxidative step. Two hydrogens are released which results in the formation of FADH₂ from FAD. This reaction is inhibited by malonate.

Step 7: Funaric acid is converted into with the malic acid help of the enzyme fumerase. Due to the addition of a water molecule(hydration) bonds in fumaric acid is rearranged.

Step 8 : This step regenerates oxaloacetic acid from malic acid which is catalysed by the enzyme malic acid dehydrogenase. This is the last oxidative step and it produces another molecule of NADH. Hence the cycle is repeated when oxaloacetic acid picks up another CO - A.