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Medicine Sem 1 > tca cycle > Flashcards

tca cycle Flashcards

1
Q

What is the TCA cycle

A

A series of 8 enzymatic reactions for the oxidation of acetyl coA
- Oxaloacetate is both a reactant and regenerated at the end of the cycle

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2
Q

What are the products of TCA cycle and what they are produced by

A
  • NADH- Produced by three dehyfrogenase reactions
    -FADH- Produced by 1 dehydrogenase
    -C02- released in 2 decarboxylation reactions
    -GTP- generated via substrate level phosphorylation
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3
Q

What is the role of the TCA cycle in Metabolism

A
  • Serves as a sharded metabolic pathway for all fuels
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4
Q

What are the 2 major Dual functions of the TCA cycle

A
  • Energy production: Facilitates ATP production
  • Biosynthesis: Produces intermediates for various biosynthesis processes
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5
Q

Describe 3 major functions of the TCA cycle

A
  • It provides a common ground for the interconversion of metabolites and fuel
  • Four oxidative steps produce free energy for ATP synthesis
  • Acetyl-CoA is common product
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6
Q

Where is Acetly-CoA loacted

A

Mitochondrial matrix

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7
Q

What are the 2 roles Acetly coA has-

A
  • Mitochondrial Role
    -Cytoplasmic Role
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8
Q

What is the function of Citrate synthesis

A
  • Catalyses the first reaction of the TCA cycle, condensing Acteyl CoA and Oxaloacetate to form citrate
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9
Q

What is the energy source for citrate synthesis

A
  • The splitting of high energy thioester bonds in a citroyl-coA
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10
Q

What is the role of Citrate

A

-Serves as a percursor for de novo lipogenesis

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11
Q

What is the name of the first and second enzyme used in the TCA cycle

A
  • Citrate synthesis
    -Aconitase
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12
Q

What is the function of Aconitase

A
  • It catalyses the reversible isomerization of citrate to isocitrate via the intermediate cis-aconitate
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13
Q

What are the 2 steps in which the reaction involed in Aconitase role in TCA cycle

A
  • dehydration followed by hydration
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14
Q

Explain Aconitases specificity

A
  • It specifically acts on the oxaloacetate end of the molecule
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15
Q

What is the name of the 3rd and 4th enzymes used in the TCA cycle

A

isocitrate dehydrogenase
- a-ketogluturate dehydrogenase

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16
Q

What is the role of both isocitrate dehydrogenase and a -ketogluturate dehydrogenase

A
  • Catalyze reactions converting isocitrate to a-ketogluturate then to succinyl coA, while reducing NAD+ to NADH and releasing C02
17
Q

What is Isocitrate dehydrogenase
-What is it inhibited and activated by and its function

A
  • Regulatory enzyme that is imhibited by high levels of NADH and ATP
  • Activated by NAD+ and ADP
  • Converts isocitrate to a -ketogluturate
18
Q

What is the function of a -ketogluturate dehydrogenase

A

converts a -ketogluturate to suxxinyl coA, NADH and C02

19
Q

Why does the net carbon yield of the TCA cycle remain zero

A
  • 2 caarbons enter as acetyl coA
  • 2 C are releases as C02, so they cancel eachother out
20
Q

What is the function of succinyl-coA synthetase

A
  • Catalyzes the conversion of succinyl-coA to succinate and a free coA
    -And GTP is formed
21
Q

How is GTP formed from succinyl coA synthetase

A
  • Energy from the high energy thioester bond in succinyl coA is conserved in the formation of GTP from GDP and pi
22
Q

What is the role of GTP

A

It is utilised in:
- Gluconeogenesis
-Protein synthesis
-Cell signaling processes

23
Q

What is succinate dehydrohenase

A
  • Flavoprotein with FAD as a prosthetic group
24
Q

Where is succinate dehydrogenase located

A
  • In the inner mitochondrial membrane
25
Q

Name the enzymes invoved in the TCA CYCLE

A

1.Citrate synthesis
2.Aconitase
3.Isocitrate dehydrogenase
4.a-ketogluturate dehydrogenase
5.Succinyl-coA synthetase
6.Succinate dehydrogenase
7.Fumerase
8.Malate Dehydrogenase

26
Q

What is the function of succinate dehydrogenase

A
  • It catalyzes the oxidation of succinate to fumarate while reducing FAD to FADH2
27
Q

What is the role of fumerase

A
  • It catalyzes the addition of water across the trans double bond of fumerate to form L-malate
  • Water is released
28
Q

What is the function of malate Dehydrogenase

A
  • Catalyses the oxidation of L-malate to Oxaloacetate.
  • Regenerates NADH
29
Q

What does the activity of the TCA cycle depend on

A
  • ## Availability of NAD+
30
Q

What is Pyruvate Dehydogenase complex inhibited by

A
  • NADH,ATP,acteyl coA(negative effectors)
31
Q

What is pyruvate Dehydrogenase complex activated by

A
  • low conc of NADH,ATP and acetyl coA
  • Insulin
32
Q

What is Anaplerosis

A
  • The replenishment of the TCA cycle intermediates to maintains its activity
33
Q

Name the key anaplerotic enzymes

A
  • pyruvate carboxylase- converts pyruvate oAA
    -Malic enzyme- Converst pyruvate to malate
    Aspartate Transamination

Medicine Sem 1 (20 decks)

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