Purines and Pyrimidines Flashcards
what does the prefix -emie refer to?
the osmolarity in the plasma
Other than the creation of proteins, what is the role of pyrimidines and purines?
Important for the creation of proteins but also ATP, GTP, UTP
Why is synthesis de novo not prefered for pyrimidines and purines?
la synthèse de novo est coûteuse en énergie, il convient de réutiliser les
pyrimidines et purines fournies par la diète
What is the organ of the de novo synthesis of pyrimidines and purines?
La synthèse de novo des purines a lieu dans le foie. Les autres tissus réutilisent
leurs propres purines générées intracellulairement.
Il existe 3 pyrimidines principales:
thymine, cytosine, uracil.
Which of the pyrimidines or purines results in not harmless catabolic products and why?
- Pyrimidines: C’est pas si pire!
Easy to recycle because they give soluble metabolites
What is the metabolic product of pyrimidine breakdown?
NH4 + CO2 (and acetyl coA which goes into krebs cycle)
Les ions NH4 (ammonium) générés sont potentiellement très toxiques mais ils
seront tout simplement éliminés par le cycle de l’urée
True or False,
Unlike purine degredation, pyramidine metabolism generates energy that can be used in form of ATP.
FALSE
Le catabolisme des pyrimidines ne génère pas de quantité significative d’énergie.
What can be clinically relevant about pyramidine metabolism?
NH4 although soluble it has to be exited otherwise it can be dangerous
For example in patients with liver problems you get build up of NH4
Les 2 purines principales sont
l’adénine et la guanine.
True or False,
Due to the expensive nature of de novo synthesis, most purines will be absorbed from the diet.
FALSE
Il y a donc peu de purines d’origine alimentaire utilisées et celles qui sont absorbées sont catabolisées en acide urique et excrétées
+++Synthèse de novo dans les hépatocytes à partir d’acides aminés
What is the metabolic product of purines?
The degradation of purines leads to Uric Acid
What is different in terms of product for purines?
The degradation of purines leads to Uric Acid
Problem because Uric acid is not soluble → hydrophobic → becomes a clump
La cristallisation de l’urate de sodium dans les tissus entraine une réaction
inflammatoire intra-articulaire (arthrite) typique d’une condition clinique bien
connue: la goutte.
A patient presents with what apears to be gait. Your boss recommends sending in for a blood test to see whether there are increased levels of uric acid. Is this the right appraoch and why?
Usually the crystals will forme in bone junctions → mono-arthritis
As such, if we want to test for “la goutte”, the acid uric in the blood will be normal so we need the existence of crystals (uric acid clumps) in the liquide synovial of the junction(exam question)
SO: DO NOT TEST THE BLOOD, IT IS SOLUBLE AND IT WILL HAVE NORMAL LEVELS IN THE BLOOD
What is Allopurinol
Treatment for Gait because is it a Xanithine Oxidase inhibitor which will decrease uric acid levels and we will have more soluble metabolites.
