18 arid 4756 bs mic 5th semester assignment krebs cycle

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ASSIGNMENT

Microbial Anatomy and Physiology

(MIC-503)

TOPIC: Carbohydrate Metabolism (group-2)

(KREBS CYCLE)

Submitted by: Safoora Anwaar

18-arid-4756

BS Microbiology (5

semester)

Submitted to: Mam Sadia Mahmood

2 | P a g e

❖ KREBS CYCLE: (Safoora Anwaar)

• Also known as Tricarboxylic acid cycle and Citric Acid cycle.

• TCA cycle essentially involves the oxidation of acetyl CoA to CO

and

H2O

• The TCA cycle is the final common oxidative pathway for carbohydrates, fats, amino acids.

• It takes place in cytosol of prokaryotes and mitochondria of eukaryotes.

• TCA cycle supplies energy & also provides many intermediates required for the synthesis

of amino acids, glucose, heme etc.

• TCA cycle is the most important central pathway connecting almost all the individual

metabolic pathways.

REACTIONS OF KREBS CYCLE:

Step: 1 Formation of citrate:

• Oxaloacetate condenses with acetyl CoA to form Citrate, catalyzed by the enzyme citrate

synthase.

Steps 2 & 3 Citrate is isomerized to isocitrate:

• Citrate is isomerized to isocitrate by the enzyme aconitase.

• This is achieved in a two stage reaction of dehydration followed by hydration through the

formation of an intermediate cis-aconitase.

Steps 4 & 5 Formation of α-ketoglutarate:

• Isocitrate dehydrogenase catalyzes the conversion of of isocitrate to oxalosuccinate & then

to α-ketoglutarate.

• The formation of NADH & the liberation of CO

occur at this stage.

Step: 6 Conversion of α-ketoglutarate to succinyl CoA:

• Occurs through oxidative decarboxylation, catalysed by α-ketoglutarate dehydrogenase

complex.

• At this stage of TCA cycle, second NADH is produced & the second CO2 is liberated.

Step: 7 Formation of succinate:

• Succinyl CoA is converted to succinate by succinate CoA synthetase.

• This reaction is coupled with the phosphorylation of GDP to GTP.

Step: 8 Conversion of succinate to fumarate:

• Succinate is oxidized by succinate dehydrogenase to fumarate.

• This reaction results in the production of FADH2.

Step: 9 Formation of malate:

• The enzyme fumarase catalyzes the conversion of fumarate to malate with the addition of

H2O.

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ASSIGNMENT Microbial Anatomy and Physiology (MIC-503) TOPIC: Carbohydrate Metabolism (group-2) (KREBS CYCLE) Submitted by: Safoora Anwaar 18-arid-4756 BS Microbiology (5th semester) Submitted to: Mam Sadia Mahmood 1|Page ❖ KREBS • • • • • • CYCLE: (Safoora Anwaar) Also known as Tricarboxylic acid cycle and Citric Acid cycle. TCA cycle essentially involves the oxidation of acetyl CoA to CO2 and H2O. The TCA cycle is the final common oxidative pathway for carbohydrates, fats, amino acids. It takes place in cytosol of prokaryotes and mitochondria of eukaryotes. TCA cycle supplies energy & also provides many intermediates required for the synthesis of amino acids, glucose, heme etc. TCA cycle is the most important central pathway connecting almost all the individual metabolic pathways. REACTIONS OF KREBS CYCLE: Step: 1 Formation of citrate: • Oxaloacetate condenses with acetyl CoA to form Citrate, catalyzed by the enzyme citrate synthase. Steps 2 & 3 Citrate is isomerized to isocitrate: • • Citrate is isomerized to isocitrate by the enzyme aconitase. This is achieved in a two stage reaction of dehydration followed by hydration through the formation of an in ...
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