Aubert Small Group Flashcards
(25 cards)
Is the following condition associated with a positive or negative nitrogen balance, or with nitrogen equilibrium: A normal, healthy adult
Equilibrium
Is the following condition associated with a positive or negative nitrogen balance, or with nitrogen equilibrium: A growing child
Positive
Is the following condition associated with a positive or negative nitrogen balance, or with nitrogen equilibrium: A pregnant woman
Positive
Is the following condition associated with a positive or negative nitrogen balance, or with nitrogen equilibrium: Following trauma
Positive and negative: immediately after will be negative, a long time after it will be positive
Is the following condition associated with a positive or negative nitrogen balance, or with nitrogen equilibrium: During regeneration of damaged tissue
Positive
Is the following condition associated with a positive or negative nitrogen balance, or with nitrogen equilibrium: During starvation
Negative
Is the following condition associated with a positive or negative nitrogen balance, or with nitrogen equilibrium: During chronic ingestion of large amounts of carbohydrates, but no protein
Negative
Is the following condition associated with a positive or negative nitrogen balance, or with nitrogen equilibrium: Chronic ingestion of apparently adequate amounts of protein, but the protein is deficient in one of the essential amino acids
Negative
Is tyrosine nutritionally essential or non-essential? How can you tell from its degradative pathway?
Non-essential because it forms from phenylalanine
What cofactor is required for phenylalanine hydroxylase, the first enzyme in the degradative pathway of phenylalanine
Tetrahydrobiopterin, it supplies 2 H+
What type of reaction is the step in which tyrosine is enzymatically converted to p-hydroxyphenylpyruvic acid?
A transamination
Are phenylalanine and tyrosine glucogenic, ketogenic, or both?
Both
What enzyme is defective in PKU?
Phenylalanine hydroxylase
What is the result of untreated PKU?
Mental retardation, abnormal EEG, seizures, extreme hyperactivity, and psychoses
What would you see in the lab assay of a newborn being tested for PKU who had the disease
Growth of a phenylalanine dependent strain of bacteria
Why did the infant need to consume milk prior to being tested for PKU
because the fetus would have normal phenylalanine levels since the mother would have the hydroxylase
What would cause the formation of phenylpyruvic acid?
A transamination reaction to relieve the buildup of toxic phenylalanine
Is tyrosine nutritionally essential or non-essential in PKU?
essential because phenylalanine cannot be broken down to produce it
Suggest a dietary treatment for classic PKU
Avoid foods with aspartame/artificial sweeteners, still need about 1% of phenylalanine
Why are diet sodas supplied with a package warning for phenylketonurics
Because aspartame is a methyl-ester of the aspartic acid-phenylalanine dipeptide
What are the 3 causes of PKU?
- defect in the synthesis of tetrahydrobiopterin
- deficiency in dihydropteridine reductase
- defect in the enzyme phenylalanine hydroxylase
Why would a defect in the synthesis of tetrahydrobiopterin or deficiency in dihydropteridine reductase result in hyperphenylalaninemia?
The cofactor for the breakdown of phenylalanine wouldn’t be available
What causes hyperammonemia in newborns?
When N-acetylglutamate synthase is deficient and working at <5% of normal levels
Why would an N-acetylglutamate synthase deficiency cause hyprammonemia
N-acetylglutamate regulates urea production. If urea production is decreased, then there will be a buildup of ammonia.
