The Catabolism of Pyruvate Flashcards
Only limited amounts of ______ are present in a cell
Glycolysis reduces ____ to ____ + ___
NADH must be __-____ to let glycolysis continue
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
how is NAD+ regenerated?
oxidative metabolism of pyruvate OR (anaerobic metabolism of pyruvate to lactate
NADH delivers electrons to what?
the respiratory chain
glycolysis takes place in ____
cytoplasm
where does the TCA cycle happen
in the mitochondria
the inner membrane contains _____ for ___ ___ ___, ___ synthase, and transport proteins
contains proteins for electron transport
chain, ATP synthase, and transport proteins
what is contained in the matrix of the mitochondria?
enzymes of the TCA cycle
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
passively, facilitated diffusion
what gradient drives the import of pyruvate into the matrix?
the pH gradient as there is a tnedency for protons to move to the matrix - creating the gradient
what is the transporter responsible for the movement of pyruvate into the matrix?
pyruvate /H+ symporter
___ gradient drives the movement of Phosphoate (Pi) into the matrix too?
pH
___ gradient drives the exchange of ATP ___ of the matrix and ADP ___ the matrix
voltage gradient, ATP out and ADP in
once in the matrix, how is pyruvate metabolised to Acetyl coA?
The -________ ____ -______ catalyses the____ _______ of pyruvate to acetyl-CoA
The pyruvate dehydrogenase complex (PDC) catalyses the oxidative decarboxylation of pyruvate to acetyl-CoA
how many enzymes make up the PDC?
3
____ activity determines glucose oxidation in well oxygenated
tissues.
PDC
the reaction by the PDC is _____
The reaction is irreversible. Acetyl-CoA cannot be converted
back to pyruvate.
reactions of PDC
- pyruvate loses ____ and hydroxyethyl TPP (HETPP) is formed
- hydroxyethyl group is transferred to ____ ___ and oxidaised to form ___ ______
- ____ group is transferred to____
- dihydrolipoamide is reoxidised
- pyruvate loses CO2 and hydroxyethyl TPP (HETPP) is formed
- hydroxyethyl group is transferred to lipoic acid and oxidised to form acetyl dihydrolipoamide
- acetyl group is transferred to CoA
- dihydrolipoamide is re-oxidised
what are the bi-products of the PDC reactions
CO2, and NAD+ is reduced to NADH and H+
what enzyme results in the formation of the HETPP complex? need to know
pyruvate dehydrogenase
what enzyme transfers the acetyl group to the CoA from acetyl dihydrolipoamide? need to know
dihydrolipoyl transacetylase
which enzyme re-oxidises the dihydrolipoamide ? need to know
dihydrolipoyl dehydrogenase
the TCA cycle involves __ reactions.
A __ carbon unit (from acetyl Co A) condenses with a __ carbon unit. The resulting __ carbon unit is ______ twice
8 reactions
A 2 carbon unit (from acetyl Co A) condenses with a 4 carbon unit. The resulting 6 carbon unit is decarboxylated twice
the decarboxylation reactions in the TCA cycle form ____ as a byproduct
CO2 - so overall there are 2 CO2 formed
there are ___ oxidation reactions in the TCA which yield 3 ____ + ___ and 1 ____
there are 4 oxidation reactions in the TCA which yield 3 NADH + H and 1 FADH2§
what energy byproduct is formed in the TCA cycle?
GTP
what are the products of the TCA cycle : summary
2 CO2
3 NADH and H+
1 FADH2
1GTP
The TCA cycle:
- OXALOACETATE (4 C) converted to ______ via ____ ____ (___ group added)
- CITRATE converted to _____ via ______
- ISOCITRATE converted to ______ via ____ _____ with the formation of ___ and ___ +___
- Alpha - KETOGLUTARATE converted to ______ -__ via ______ ______ with the formation of ___ and ___ +___
- SUCCINYL-COA converted to _____ via _____ with the formation of ___
- SUCCINATE converted to ______ via ____ _____ with the formation of ___
- FUMARATE converted to _____ via ______
- MALATE converted to _____ via _____ _____ with the formation of ___
The TCA cycle:
- OXALOACETATE (4 C) converted to CITRATE via CITRATE SYNTHASE (ACETYL group added)
- CITRATE converted to ISOCITRATE via ACONITRASE
- ISOCITRATE converted to ALPHA-KETOGLUTARATE via ISOCITRATE DEHYDROGENASE with the formation of CO2 and NADH + H+
- Alpha - KETOGLUTARATE converted to SUCCINYL COA via ALPHA -KETOGLUTARE DEHYDROGENASE with the formation of CO2 and NADH + H+
- SUCCINYL-COA converted to SUCCINATE via SUCCINYL-COA SYNTHASE with the formation of GTP
- SUCCINATE converted to FUMARATE via SUCCINATE DEHYDROGENASE with the formation of FADH2
- FUMARATE converted to MALATE via FUMARASE
- MALATE converted to OXALOACETATE via MALATE DEHYDROGENASE with the formation of NADH + H+
All enzymes of the TCA cycle are located in the mitochondrial matrix, apart from:
____ ____-
SUCCINYL DEHYDROGENASE
what does succinate dehydrogenase do?
converts succinate and FAD to fumarate and FADH2
where is succinate dehydrogenase found?
in the inner mitochondrial membrane
which four enzymes in the TCA cycle (starting from pyruvate formation) are control points ?
- Pyruvate dehydrogenase complex
- citrate synthase
- isocitrate dehydrogenase
- alpha - ketoglutarate dehydrogenase
which enzyme of TCA cycle (starting from pyruvate formation) is inhibited by ATP, acetyl - Coa and NADH
- Pyruvate dehydrogenase complex
which enzyme of TCA cycle (starting from pyruvate formation) is inhibited by ATP, succinyl- Coa, citrate and NADH
- citrate synthase
which enzyme of TCA cycle (starting from pyruvate formation) is inhibited by ATP and NADH and stimulated by ADP and NAD+
- isocitrate dehydrogenase
which enzyme of TCA cycle (starting from pyruvate formation) is inhibited by ATP, succinyl Coa and NADH
- alpha - ketoglutarate dehydrogenase
from each molecule of GLUCOSE, how many of each are generated
ATP: NADH: H+: FADH2: CO2:
ATP: 4 NADH: 10 H+: 10 FADH2: 2 CO2: 4
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
2, X linked
PDCD Presents largely as _____l disease
in children
Presents largely as neurological disease
in children
- may get Persistent lactic
acidosis
on CT what is shown with PDCD?
brain lesions
defective symmetry of left and right hemispheres
what enzyme defect in the TCA causes “Hereditary Leiomyomatosis and Renal Cell Cancer
fumarase (fumarate hydratase)
