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Principles: biochemistry > The Catabolism of Pyruvate > Flashcards

The Catabolism of Pyruvate Flashcards

1
Q

Only limited amounts of ______ are present in a cell

Glycolysis reduces ____ to ____ + ___

NADH must be __-____ to let glycolysis continue

A

Only limited amounts of NAD+ are present in a cell

Glycolysis reduces NAD+ to NADH + H+

NADH must be re-oxidised to let glycolysis continue

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2
Q

how is NAD+ regenerated?

A

oxidative metabolism of pyruvate OR (anaerobic metabolism of pyruvate to lactate

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3
Q

NADH delivers electrons to what?

A

the respiratory chain

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4
Q

glycolysis takes place in ____

A

cytoplasm

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5
Q

where does the TCA cycle happen

A

in the mitochondria

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6
Q

the inner membrane contains _____ for ___ ___ ___, ___ synthase, and transport proteins

A

contains proteins for electron transport

chain, ATP synthase, and transport proteins

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7
Q

what is contained in the matrix of the mitochondria?

A

enzymes of the TCA cycle

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8
Q

pyruvate has to cross two membranes o get to the matrix for the TCA cycle.

It crosses the first _____ as it is negatively charged but needs ____ ____ to move across the inner membrane

A

passively, facilitated diffusion

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9
Q

what gradient drives the import of pyruvate into the matrix?

A

the pH gradient as there is a tnedency for protons to move to the matrix - creating the gradient

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10
Q

what is the transporter responsible for the movement of pyruvate into the matrix?

A

pyruvate /H+ symporter

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11
Q

___ gradient drives the movement of Phosphoate (Pi) into the matrix too?

A

pH

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12
Q

___ gradient drives the exchange of ATP ___ of the matrix and ADP ___ the matrix

A

voltage gradient, ATP out and ADP in

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13
Q

once in the matrix, how is pyruvate metabolised to Acetyl coA?

The -________ ____ -______ catalyses the____ _______ of pyruvate to acetyl-CoA

A

The pyruvate dehydrogenase complex (PDC) catalyses the oxidative decarboxylation of pyruvate to acetyl-CoA

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14
Q

how many enzymes make up the PDC?

A

3

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15
Q

____ activity determines glucose oxidation in well oxygenated
tissues.

A

PDC

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16
Q

the reaction by the PDC is _____

A

The reaction is irreversible. Acetyl-CoA cannot be converted
back to pyruvate.

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17
Q

reactions of PDC

  1. pyruvate loses ____ and hydroxyethyl TPP (HETPP) is formed
  2. hydroxyethyl group is transferred to ____ ___ and oxidaised to form ___ ______
  3. ____ group is transferred to____
  4. dihydrolipoamide is reoxidised
A
  1. pyruvate loses CO2 and hydroxyethyl TPP (HETPP) is formed
  2. hydroxyethyl group is transferred to lipoic acid and oxidised to form acetyl dihydrolipoamide
  3. acetyl group is transferred to CoA
  4. dihydrolipoamide is re-oxidised
18
Q

what are the bi-products of the PDC reactions

A

CO2, and NAD+ is reduced to NADH and H+

19
Q

what enzyme results in the formation of the HETPP complex? need to know

A

pyruvate dehydrogenase

20
Q

what enzyme transfers the acetyl group to the CoA from acetyl dihydrolipoamide? need to know

A

dihydrolipoyl transacetylase

21
Q

which enzyme re-oxidises the dihydrolipoamide ? need to know

A

dihydrolipoyl dehydrogenase

22
Q

the TCA cycle involves __ reactions.

A __ carbon unit (from acetyl Co A) condenses with a __ carbon unit. The resulting __ carbon unit is ______ twice

A

8 reactions

A 2 carbon unit (from acetyl Co A) condenses with a 4 carbon unit. The resulting 6 carbon unit is decarboxylated twice

23
Q

the decarboxylation reactions in the TCA cycle form ____ as a byproduct

A

CO2 - so overall there are 2 CO2 formed

24
Q

there are ___ oxidation reactions in the TCA which yield 3 ____ + ___ and 1 ____

A

there are 4 oxidation reactions in the TCA which yield 3 NADH + H and 1 FADH2§

25
Q

what energy byproduct is formed in the TCA cycle?

A

GTP

26
Q

what are the products of the TCA cycle : summary

A

2 CO2

3 NADH and H+

1 FADH2

1GTP

27
Q

The TCA cycle:

  1. OXALOACETATE (4 C) converted to ______ via ____ ____ (___ group added)
  2. CITRATE converted to _____ via ______
  3. ISOCITRATE converted to ______ via ____ _____ with the formation of ___ and ___ +___
  4. Alpha - KETOGLUTARATE converted to ______ -__ via ______ ______ with the formation of ___ and ___ +___
  5. SUCCINYL-COA converted to _____ via _____ with the formation of ___
  6. SUCCINATE converted to ______ via ____ _____ with the formation of ___
  7. FUMARATE converted to _____ via ______
  8. MALATE converted to _____ via _____ _____ with the formation of ___
A

The TCA cycle:

  1. OXALOACETATE (4 C) converted to CITRATE via CITRATE SYNTHASE (ACETYL group added)
  2. CITRATE converted to ISOCITRATE via ACONITRASE
  3. ISOCITRATE converted to ALPHA-KETOGLUTARATE via ISOCITRATE DEHYDROGENASE with the formation of CO2 and NADH + H+
  4. Alpha - KETOGLUTARATE converted to SUCCINYL COA via ALPHA -KETOGLUTARE DEHYDROGENASE with the formation of CO2 and NADH + H+
  5. SUCCINYL-COA converted to SUCCINATE via SUCCINYL-COA SYNTHASE with the formation of GTP
  6. SUCCINATE converted to FUMARATE via SUCCINATE DEHYDROGENASE with the formation of FADH2
  7. FUMARATE converted to MALATE via FUMARASE
  8. MALATE converted to OXALOACETATE via MALATE DEHYDROGENASE with the formation of NADH + H+
28
Q

All enzymes of the TCA cycle are located in the mitochondrial matrix, apart from:
____ ____-

A

SUCCINYL DEHYDROGENASE

29
Q

what does succinate dehydrogenase do?

A

converts succinate and FAD to fumarate and FADH2

30
Q

where is succinate dehydrogenase found?

A

in the inner mitochondrial membrane

31
Q

which four enzymes in the TCA cycle (starting from pyruvate formation) are control points ?

A
  1. Pyruvate dehydrogenase complex
  2. citrate synthase
  3. isocitrate dehydrogenase
  4. alpha - ketoglutarate dehydrogenase
32
Q

which enzyme of TCA cycle (starting from pyruvate formation) is inhibited by ATP, acetyl - Coa and NADH

A
  1. Pyruvate dehydrogenase complex
33
Q

which enzyme of TCA cycle (starting from pyruvate formation) is inhibited by ATP, succinyl- Coa, citrate and NADH

A
  1. citrate synthase
34
Q

which enzyme of TCA cycle (starting from pyruvate formation) is inhibited by ATP and NADH and stimulated by ADP and NAD+

A
  1. isocitrate dehydrogenase
35
Q

which enzyme of TCA cycle (starting from pyruvate formation) is inhibited by ATP, succinyl Coa and NADH

A
  1. alpha - ketoglutarate dehydrogenase
36
Q

from each molecule of GLUCOSE, how many of each are generated

ATP: 
NADH: 
H+: 
FADH2: 
CO2:
A 
ATP: 4
NADH: 10
H+: 10
FADH2: 2
CO2: 4
37
Q 
Pyruvate Dehydrogenase (PDH) is an enzyme of the pyruvate 
dehydrogenase complex. This enzyme can be deficient: an example of a stage \_\_ metabolic disorder. It is \_\_ linked
A

2, X linked

38
Q

PDCD Presents largely as _____l disease

in children

A

Presents largely as neurological disease
in children

  • may get Persistent lactic
    acidosis
39
Q

on CT what is shown with PDCD?

A

brain lesions

defective symmetry of left and right hemispheres

40
Q

what enzyme defect in the TCA causes “Hereditary Leiomyomatosis and Renal Cell Cancer

A

fumarase (fumarate hydratase)

Principles: biochemistry (7 decks)

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