Nitrogen 1-3 Flashcards
How does Nitrogen enter the body ?
Through diet
How many covelant bonds does Nitrogen have ?
Three
What is the name of the enzyme that bacteria use to break the bonds found in Nitrogen & what affects this enzyme ?
Nitrogenase
Inactivated by Oxygen: Live anaerobically
What kind of bacteria can form structures that resemble cell walls ?
Cynobacteria
What do leguminous plants contain that assist in Oxygen binding ?
They produce hemoglobin
What form must Nitrogen be before it is taken up by bacteria & plants ?
Nitrate (NO3)
What is the product of Alpha-Ketogluterate + Ammonium ?
Glutamate
Alpha-Ketogluterate is an intermediate from which other biochemical cycle ?
CAC
What Amino Acid is crucial for Nitrogen to enter the cells of the body ?
Glutamate
What 2 Amino Acids also act as excitatory neurotransmitters ?
Glutamate and Aspertate
Define transamination?
An amino acid giving up an amino acid group to form a Keto-acid and an amino acid
Why is transamination used ?
To conserve Nitrogen in an organism
What co-factor do Amino Transferases rely on & where does this originate from ?
Pyridoxal Phosphate Co-factor and it is derived from Vitamin B6
What does L-Glutamine do ?
Acts as a temporary storage for Nitrogen in the body
Amino acids undergo oxidative catabolism under what three conditions ?
1: Leftover A.A. from normal turnover and degradation
2: When there is an excessive amount of dietary A.A that exceed the body’s protein synthesis.
3: During starvation protein is broken down due to the lack of carbohydrates
What cuts protein into peptides in the stomach ?
Pepsin
What acts in the small intestine to cut down proteins & larger peptides into smaller peptides ?
Trypsin and Chymotrypsin
What acts in the small intestine to degrade peptides into amino acids ?
Aminopeptidase and Carboxypeptidases A and B
How are active proteases stored in the small intestinal cells ?
Zymogens
What happens to defective proteins ?
They are regulated and broken down by proteosome into peptide fragments and Released Ubiquitin
How is Nitrogen excreted from the body ?
As urea
Properties of urea
Highly soluble and non-toxic
What are the properties of ammonia that have to be considered when transporting through the body ?
Highly toxic
how is Ammonia transported through the bloodstream ?
As Alanine
What is the name of the cycle that carries Alanine from muscle to the liver via the bloodstream ?
Glucose-Alanine Cycle
When would the body utilize the Glucose-Alanine Cycle ?
During starvation
What other cycle is much like the Glucose-Alanine cycle and when would it be utilized ?
The cori cycle - during exercise.
What kind of charge does Glutamate have ?
-ve charge
What kind of charge does Alanine and Glutamine have and what does that mean with regards to membranes ?
No charge - easier to pass through membranes
Where is excess Glutamate metabolized ?
The mitochondria of the hepatocytes
What does Oxaloacetate get metabolized into once combined with alpha-ketogluterate in the Mitochondria ?
Aspertate
What is the first Nitrogen Acquiring reaction in the Mitochondria ?
Glutamate -> Carbomyl Posphate
What does Carbomyl Phosphate turn into before it leave the Mitochondria ?
Citruline
What also leaves the Mitochondria to meet up with Citruline in the Cytoplasm and what does this create ?
Aspertate meets with Citruline in the cytoplasm to form Arginosuccinate & this is the 2nd nitrogen acquiring reaction
What is the order of events from Arginosuccinate to urea production ?
Arginosucinate -> Arginine -> H2O = Urea
What are the two broad classes of Amino Acid ?
Glucogenic and Ketogenic
What do Glucogenic amino acids generally go on to become ?
Oxaloacetate -> Glucose
What do Ketogenic amino acids generally go on to become ?
Ketone Bodies
How many disorders of the urea cycle are there ?
there are 6
What is the most common disorder of the urea cycle ?
The most common is an ornitine transcarbamoylase (OTC) deficiency.
What is the purpose of OTC ?
Turns Ornitine back into Citruline in the urea cycle
How is OTC deficiency inherited ?
It is an x linked inheritance
How is OTC deficiency usually characterized ?
By hyperammonaemia (abnormally high levels of ammonia in the blood) which can be toxic
In what age bracket does OTC deficiency usually present ?
New born
In which cycle is OTC deficiency disorder found ?
The urea cycle
In amino acid disorders decreased enzyme activity will do what to the product and the precursors ?
Decrease the product and increase the precursors
What is one of the most common amino avid disorders ?
Phenylketonuria (PKU)
How is PKU defined ?
as an absence or deficiency of Phenylalanine Hydroxylase (PAH)
What is the purpose of the enzyme PAH ?
It catalyses the reaction of Phenylalanine to Tyrosine
What occurs in this pathway when PAH is not present ?
There is a build up of Phenylalanine and Phenylalanine turns into Phenylpyruvate and then phenylacetate
What occurs in an individual who has not been treated for PKU ?
Impaired brain development
How is PKU treated ?
Decreased amounts of dietary protein and tyrosine supplements
What is generated from Tyrosine ?
Thyroxine & L-DOPA
When is PKU usually first spotted in babies ?
Once they start feeding phenylalanine levels will rise
