Nitrogen Flashcards
What do amino acids and nucleotides contain that carbohydrates and fats don’t?
Nitrogen
Where do we get nitrogen from?
our diet
What does pepsin do?
cuts protein into peptides in the stomach
What do trypsin and chymotrypsin do?
cut proteins and larger peptides into smaller peptides in the small intestine
What do amino peptides and carboxy peptides A and B do?
degrade peptides into amino acids in the small intestine
What happens to dietary proteins?
They get enzymatically hydrolysed and broken down to eventually make AA
Primary role of carbs and fat?
to provide energy
Primary role of amino acids?
building blocks for proteins
What happens at the end of protein destruction?
produce individual AA
What enzyme converts phenylalanine to tyrosine?
Phenylalanine hydroxylase
What does phenylketonuria involve? (PKU)
absence/ deficiency of Phenylalanine hydroxylase
lots of phenylalanine building up and becomes other products such as Phenylpyruvate, Phenyllactate, Hydroxyphenylacetate and phenylacetate
spill over and appear in urine
Problem is that these products also cross the blood brain barrier, and cause irreversible damage to the developing brain
How does PKU manifest genetically?
two disease copies of brain, one from each parent
Clinical features of PKU?
Normal at birth with near normal blood Phe levels
Phe levels rise rapidly once feeding is established
Days 3-4 may present with irritability and feeding difficulties
If untreated, delayed mental development and neurological features are evident by 6 months of age
Musty odour
Neonatal screening program?
use of guthrie card
few spots of blood taken from blood sample
spotted onto circles
allowed to dry
Steps after PKU positive test?
Positive screening test
Quantitative amino acid analysis
Confirmation of increased blood Phe level
Typically decreased blood Tyrosine (Tyr) level
Presumptive diagnosis of PKU
Dietary treatment started immediately
