The Pyruvate Dehydrogenase Complex and the TCA cycle. Flashcards
What are co-enzymes?
Small organic molecules that will help an enzyme perform its job. Co-enzymes are often derived from vitamins.
What are kinases?
These enzymes will add phosphate groups to proteins.
What amino acid residues get phosphorylated?
Serine.
Threonine.
Tyrosine residues.
What are phosphatases?
These enzymes will remove phosphate groups from proteins.
What is the final product of glycolysis?
2 Pyruvate molecules.
How many carbons does each pyruvate molecule have?
3.
What happens when pyruvate is oxidised further?
All of the electrons are removed to form CO2 and water.
Is the breakdown of pyruvate catabolic or anabolic?
Catabolic.
What are the goals of the PDH cycle and the ETC?
To get energy out of pyruvate.
Where are the 2 molecules of pyruvate formed?
In the cytoplasm.
Where are the enzymes for the TCA cycle and the PDH cycle found?
In the mitochondria.
What are the main energy producers in the cell?
The mitochondria.
Describe the interior of the mitochondria?
The interior of a mitochondrion is made up of 2 layers or membranes that are separated by a space.
What are the 2 membranes in the mitochondria called?
The outer and inner membrane.
What is the space between the outer an inner membrane called?
The inter-membranous space.
Why is the inner mitochondrial membrane invaginated?
To increase surface area.
Is the inner mitochondrial membrane easy for molecules to penetrate?
No.
It is highly impermeable.
Where in the mitochondria does the TCA cycle and PDH step occur?
In the mitochondrial matrix.
Where is the mitochondrial matrix located?
On the inside of the inner mitochondrial membrane.
What metabolic functions occur in the outer membrane of the mitochondria?
Phospholipid synthesis.
Fatty acid de-saturation.
Fatty acid elongation.
What metabolic functions occur in the inner membrane of the mitochondria?
Electron transport.
Oxidative phosphorylation.
Metabolite transport.
What metabolic functions occur in the inter membranous space of the mitochondria?
Nucleotide phosphorylation
What metabolic functions occur in the mitochondrial matrix of the mitochondria?
TCA cycle.
Pyruvate oxidation.
DNA replication.
Beta oxidation of fats.
Protein synthesis.
RNA synthesis.
Does the PDH step or the TCA cycle occur first?
The pyruvate molecules enter the PDH complex first then go into the TCA cycle.
What is formed in the PDH complex?
Pyruvate is oxidised to ACoA.
How many carbons does ACoA have?
2.
Are the any by products of the oxidation of pyruvate to ACoA in the PDH step?
The carbon that is removed from pyruvate is lost as CO2.
The energy from the oxidation forms an NADH.
What molecule enters the TCA cycle?
ACoA.
Can the formation of ACoA from pyruvate be reversed?
No.
The reaction is irreversible.
Is the PDH complex a single enzyme or multiple enzymes?
A single enzyme.
Where is the PDH complex found?
In the mitochondrial matrix.
How many enzymes does the PDH complex contain?
3.
How many regulatory proteins does the PDH complex contain?
2.
How many coenzymes does the PDH complex require so that it can function?
5.
What are the 3 enzymes or catalytic proteins in the PDH complex?
Pyruvate dehydrogenase.
Dihydrolipoyl dehydrogenase.
Dihydrolipoyl transacetylase.
What are the 2 regulatory proteins in the PDH complex?
Protein kinase (PDH kinase).
Protein phosphatase (PDH phosphatase).
What are the 5 coenzymes required by the PDH complex?
NAD+.
FAD.
Thiamine pyrophosphate (TPP).
Lipoic acid.
CoASH (co-enzyme A).
Nobody.
Fucks.
The.
Large.
Chicks.
What happens if a coenzyme is missing from the PDH complex?
Then the PDH complex cannot function.
Which coenzymes are vitamins?
NAD+.
FAD.
Thiamine pyrophosphate (TPP).
CoASH (co-enzyme A).
Which coenzyme is not a vitamin?
Lipoic acid.
How are the co-enzymes that are vitamins in the PDH complex acquired?
From the diet.
What enzymes in the PDH complex are involved in the conversion of pyruvate to ACoA?
All 3 of them.
Which co-enzymes will carry the acetyl group through the complex and to give it to CoA and form ACoA?
Co-ASH and TPP.
Which co-enzymes will transfer electrons from substances that have been oxidised to eventually form NADH.
Lipoic acid, NAD+ and FAD
What will be the output of 1 pyruvate molecule in the PDH complex?
1 ACoA, 1 Pyruvate and 1 CO2.
What will be the output of 1 glucose molecule in the PDH complex?
2 ACoA, 2 Pyruvate and 2 CO2.
When will the PDH complex be active?
When it is de-phosphorylated.
What will de-phosphorylate the PDH complex?
The regulatory enzyme, PDH phosphatase.
What stimulates the de-phosphorylation of the PDH complex by PDH phosphatase?
High levels of insulin in the liver.
High levels of calcium or magnesium in skeletal muscle.
When will the PDH complex not be active?
When it is phosphorylated.
What will phosphorylate the PDH complex?
The regulatory enzyme, PDH kinase.
What will activate PDH kinase?
ATP.
ACoA.
NADH.
Other than the PDH complex, what other methods can be used to create ACoA?
Triglycerides to ACoA.
Protein to ACoA.
Glycogen to ACoA.
How does glycogen for ACoA?
It can be broken down by glycogenolysis to form glucose.
Glucose can then form pyruvate.
What are triglycerides?
Fats which are a form of stored energy.
How can triglycerides form ACoA?
Triglycerides are broken down to glycerol and free fatty acids by lipolysis.
Free fatty acids are then broken down via beta oxidation to form ACoA.
How can proteins be used to form ACoA?
Via proteolysis which breaks them down to amino acids.
The amino acids can be broken down by oxidative de-amination to ACoA.
What other names can the TCA cycle be referred to as?
The tricarboxylic acid cycle (TCA cycle).
The krebs cycle.
The citrate cycle.
Where does the TCA cycle occur?
In the mitochondrial matrix.
What happens in the 1st step of the TCA cycle?
ACoA is added to oxaloacetate which creates a molecule called citrate.
