The Catabolism of Pyruvate

Question 1

Only limited amounts of ______ are present in a cell

Glycolysis reduces ____ to ____ + ___

NADH must be __-____ to let glycolysis continue

Answer 1

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

Question 2

how is NAD+ regenerated?

Answer 2

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

Question 3

NADH delivers electrons to what?

Answer 3

the respiratory chain

Question 4

glycolysis takes place in ____

Answer 4

cytoplasm

Question 5

where does the TCA cycle happen

Answer 5

in the mitochondria

Question 6

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

Answer 6

contains proteins for electron transport

chain, ATP synthase, and transport proteins

Question 7

what is contained in the matrix of the mitochondria?

Answer 7

enzymes of the TCA cycle

Question 8

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

Answer 8

passively, facilitated diffusion

Question 9

what gradient drives the import of pyruvate into the matrix?

Answer 9

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

Question 10

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

Answer 10

pyruvate /H+ symporter

Question 11

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

Answer 11

pH

Question 12

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

Answer 12

voltage gradient, ATP out and ADP in

Question 13

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

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

Answer 13

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

Question 14

how many enzymes make up the PDC?

Answer 14

3

Question 15

____ activity determines glucose oxidation in well oxygenated
tissues.

Answer 15

PDC

Question 16

the reaction by the PDC is _____

Answer 16

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

Question 17

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

Answer 17

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

Question 18

what are the bi-products of the PDC reactions

Answer 18

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

Question 19

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

Answer 19

pyruvate dehydrogenase

Question 20

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

Answer 20

dihydrolipoyl transacetylase

Question 21

which enzyme re-oxidises the dihydrolipoamide ? need to know

Answer 21

dihydrolipoyl dehydrogenase

Question 22

the TCA cycle involves __ reactions.

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

Answer 22

8 reactions

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

Question 23

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

Answer 23

CO2 - so overall there are 2 CO2 formed

Question 24

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

Answer 24

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

Question 25

what energy byproduct is formed in the TCA cycle?

Answer 25

GTP

Question 26

what are the products of the TCA cycle : summary

Answer 26

2 CO2 3 NADH and H+ 1 FADH2 1GTP

Question 27

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 ___

Answer 27

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+

Question 28

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

Answer 28

SUCCINYL DEHYDROGENASE

Question 29

what does succinate dehydrogenase do?

Answer 29

converts succinate and FAD to fumarate and FADH2

Question 30

where is succinate dehydrogenase found?

Answer 30

in the inner mitochondrial membrane

Question 31

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

Answer 31

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

Question 32

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

Answer 32

1. Pyruvate dehydrogenase complex

Question 33

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

Answer 33

2. citrate synthase

Question 34

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

Answer 34

3. isocitrate dehydrogenase

Question 35

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

Answer 35

4. alpha - ketoglutarate dehydrogenase

Question 36

from each molecule of GLUCOSE, how many of each are generated ``` ATP: NADH: H+: FADH2: CO2: ```

Answer 36

``` ATP: 4 NADH: 10 H+: 10 FADH2: 2 CO2: 4 ```

Question 37

``` 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 ```

Answer 37

2, X linked

Question 38

PDCD Presents largely as _____l disease | in children

Answer 38

Presents largely as neurological disease in children - may get Persistent lactic acidosis

Question 39

on CT what is shown with PDCD?

Answer 39

brain lesions defective symmetry of left and right hemispheres

Question 40

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

Answer 40

fumarase (fumarate hydratase)