Citrate cycle cc exercise
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Citrate Cycle (CC) - exercise -. Vladimíra Kvasnicová. Citrate cycle is also called. citric acid cycle tricarboxylic acid cycle Krebs cycle electron transport chain. Citrate cycle is also called. citric acid cycle tricarboxylic acid cycle Krebs cycle electron transport chain.

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Citrate Cycle (CC) - exercise -

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Citrate Cycle (CC)- exercise -

Vladimíra Kvasnicová


Citrate cycle is also called

  • citric acid cycle

  • tricarboxylic acid cycle

  • Krebs cycle

  • electron transport chain


Citrate cycle is also called

  • citric acid cycle

  • tricarboxylic acid cycle

  • Krebs cycle

  • electron transport chain


The figure is adopted from the book: Devlin, T. M. (editor): Textbook of Biochemistry with Clinical Correlations, 4th ed. Wiley‑Liss, Inc., New York, 1997. ISBN 0‑471‑15451‑2


simplification:

The figure is found at http://www.sp.uconn.edu/~bi107vc/images/mol/krebs_cycle.gif (December 2006)


citric acid

(2-hydroxypropane-1,2,3-tricarboxylicacid)


Hans Adolf Krebs

The Nobel Prize in Physiology or Medicine in 1953 for his discovery of the citric acid cycle.


= the other metabolic pathway

The figure is adopted from the book: Devlin, T. M. (editor): Textbook of Biochemistry with Clinical Correlations, 4th ed. Wiley‑Liss, Inc., New York, 1997. ISBN 0‑471‑15451‑2


Citrate cycle

  • is a catabolic pathway

  • participates in anabolic reactions

  • belongs among oxidative processes

  • produces carbon dioxide


Citrate cycle

  • is a catabolic pathway

  • participates in anabolic reactions

  • belongs among oxidative processes

  • produces carbon dioxide


The figure is found at http://www.holon.se/folke/kurs/Distans/Ekofys/Recirk/Eng/regcyc5.jpg (December 2006)


Amphibolic nature of thecitrate cycle

The figure is found athttp://www.tcd.ie/Biochemistry/IUBMB-Nicholson/gif/13.html


Enzymes of the citrate cycle

  • are found in all cells

  • are located in a mitochondrion

  • catalyze freely reverzible reactions

  • produce coenzymes which are regenerated in a respiratory chain


Enzymes of the citrate cycle

  • are found in all cells

  • are located in a mitochondrion

  • catalyze freely reverzible reactions

  • produce coenzymes which are regenerated in a respiratory chain


strongly exergonic reactions

The figure is found at http://www.metabolic-database.com/html/body_glutaminolysis__zeichnung3.html (December 2006)


The substances enter the CC

  • acetyl~CoA

  • NAD+ and FAD

  • carbon skeleton of amino acids

  • GDP


The substances enter the CC

  • acetyl~CoA (→ 2 CO2)

  • NAD+ and FAD (→ NADH+H+ + FADH2)

  • carbon skeleton of amino acids

  • GDP (→ GTP)


The figure is found at http://www.elmhurst.edu/~chm/vchembook/images/590metabolism.gif (December 2006)


Choose products of the cycle

  • pyruvate

  • acetyl-CoA

  • NADH

  • FADH2


Choose products of the cycle

  • pyruvate

  • acetyl-CoA

  • NADH(→ electron transport chain)

  • FADH2(→ electron transport chain)


Products of the citrate cycle

The figure is found at http://www.hupe.hu/szerv/tanszekek/kio/im/oktat/SEJTBIO/citratkor/citr_summa_e.html (December 2006)


Energy released from oxidation of acetyl group in the CC is conserved in

  • GTP

  • ATP

  • NADH

  • FADH2


Energy released from oxidation of acetyl group in the CC is conserved in

  • GTP(succinyl~Co → succinate)

  • ATP (GTP + ADP → GDP + ATP)

  • NADH (3x)

  • FADH2 (1x)


The figure is found at http://lecturer.ukdw.ac.id/dhira/Metabolism/Respiration.html (December 2006)


NAD+ is reduced to NADH+H+ in the reactions of the CC

  • isocitrate → -ketoglutarate

  • -ketoglutarate → succinyl~CoA

  • succinate → fumarate

  • malate → oxaloacetate


NAD+ is reduced to NADH+H+ in the reactions of the CC

  • isocitrate → -ketoglutarate

  • -ketoglutarate → succinyl~CoA

  • succinate → fumarate

  • malate → oxaloacetate


„F“ →Fumarateand FADH2

The figure is found at http://lecturer.ukdw.ac.id/dhira/Metabolism/Respiration.html (December 2006)


Carbon dioxide (CO2) is produced in the reactions of the CC

  • oxaloacetate + acetyl~CoA → citrate

  • citrate → isocitrate

  • isocitrate → -ketoglutarate

  • -ketoglutarate → succinyl~CoA


Carbon dioxide (CO2) is produced in the reactions of the CC

  • oxaloacetate(C4) + acetyl~CoA(C2) → citrate(C6)

  • citrate (C6)→ isocitrate (C6)

  • isocitrate (C6)→ -ketoglutarate(C5)

  • -ketoglutarate(C5)→ succinyl~CoA(C4)

    ! count number of carbons !


The figure is found at http://lecturer.ukdw.ac.id/dhira/Metabolism/Respiration.html (December 2006)


Choose reactions that lead tonet synthesis of CC intermediates(= anaplerotic reactions)

  • pyruvate → acetyl~CoA (PDH)

  • pyruvate → oxaloacetate (pyruvate carboxylase)

  • aspartate → oxaloacetate(AST)

  • glutamate → -ketoglutarate(ALT)


Choose reactions that lead tonet synthesis of CC intermediates(= anaplerotic reactions)

  • pyruvate → acetyl~CoA(PDH)

  • pyruvate → oxaloacetate(pyruvate carboxylase)

  • aspartate → oxaloacetate(AST) – the reaction consumes 2-oxoglutarate (+1 -1 = 0 net synthesis)

  • glutamate → -ketoglutarate(ALT)


The figure is found at http://web.indstate.edu/thcme/mwking/tca-cycle.html (prosinec 2006)


The most important anaplerotic reaction:

pyruvate carboxylase

The figure is found at http://www.bmb.leeds.ac.uk/illingworth/metabol/2120lec3.htm#krebs (December 2006)


The substances can be synthesized from intermediates of the CC

  • amino acids

  • heme

  • glucose

  • fatty acids


The substances can be synthesized from intermediates of the CC

  • amino acids

  • heme

  • glucose

  • fatty acids


Citrate cycleas a source of substrates used in a synthesis of other molecules

The figure is found athttp://www.tcd.ie/Biochemistry/IUBMB-Nicholson/gif/13.html


The enzymes regulate velocity of the CC

  • citrate synthase

  • isocitrate dehydrogenase

  • -ketoglutarate dehydrogenase

  • hexokinase


The enzymes regulate velocity of the CC

  • citrate synthase

  • isocitrate dehydrogenase

  • -ketoglutarate dehydrogenase

  • hexokinase


The citrate cycle is inhibited by

  •  ATP/ADP

  •  NADH,  NAD+

  •  NADH/NAD+

  •  AMP


The citrate cycle is inhibited by

  •  ATP/ADP

  •  NADH,  NAD+

  •  NADH/NAD+

  •  AMP


Regulation of the citrate cycle

= by availability of substrates and consumption of produts


Citrate

  • is formed from oxaloacetate and acetic acid

  • is transported to the cytoplasm if accumulates

  • acts as an inhibitor of glycolysis

  • activates synthesis of fatty acids


Citrate

  • is formed from oxaloacetate and acetic acid

  • is transported to the cytoplasm if accumulates

  • acts as an inhibitor of glycolysis

  • activates synthesis of fatty acids

    energy excess → it is stored in a glycogen and fat


ATP

The figure is found at http://www.metabolic-database.com/html/body_glutaminolysis__zeichnung3.html (December 2006)


see next presentation

The figure is adopted from the book: Devlin, T. M. (editor): Textbook of Biochemistry with Clinical Correlations, 4th ed. Wiley‑Liss, Inc., New York, 1997. ISBN 0‑471‑15451‑2


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