i am not sure if any of this is correct. help!!! 3. What is the difference betwe
ID: 269028 • Letter: I
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i am not sure if any of this is correct. help!!!
3. What is the difference between de novo synthesis of nucleotides and nucleotide/nucleoside salvage pathways. Are the salvage pathways important? Why or why not? .Salvage pathways are more important because it takes more resources to make purines. Adenine and guanine can be degraded to Uric Acid- accumulation of uric acid can cause gout. When adenine accumulates it can cause issues with DNA synthesis 0 4. Does de novo synthesis of nucleotides produce Cribonucleotidès or deoxyribonucleotides? 2 5. De novo purine synthesis: 8 Know the precursor of each carbon and nitrogen atom in the purine ring. Starting with the synthesis of PRPP describe the synthesis of AMP and GMP. Are mono-, di- or triphosphates synthesized by this pathway?Explanation / Answer
De novo synthesis is the formation of complex components from simple molecules. De novo synthesis of DNA and RNA involves two types of nucleotides called purines (Adenine & Guanine) and pyrimidines (Thymine, Cytosine and Uracil). In this pathway all the nucleotides essential for DNA & RNA synthesis are produced from simple precursor molecules.
Salvage pathway synthesises nucleotides from intermediates formed from degradation of RNA and DNA. This is an alternative pathway in some cell types which cannot synthesise nucleotides by de novo pathway. Hypoxanthine is one of the important purine nucleotide involved in salvage pathway.
Salvage pathway is important because most of the purine nucleotide re-synthesis takes place through this. The three important enzymes that play vital role in the conversion of purines to nucleotides are as follows;
1. Adenine is catalysed to AMP (Adenosine monophosphate) by the enzyme adenine phosphoribosyl transferase (APRT).
2. Guanine is catalysed to GMP (Guanosine monophosphate) by the enzyme hypoxanthine-guanine phosphoribosyl transferase (HGPRT).
3. Hypoxanthine is catalysed to IMP (Inosine monophosphate) by the enzyme HGPRT.
Purine catabolism takes place in the liver of human body. Adenosine and Guanine and deaminated by their respective deaminases to form uric acid. Uric acid is then excreted out of the body. But sometimes defects in purine catabolism caused by the malfunction of enzyme adenosine deaminase leads to the accumulation of Uric acid in the body. This diseased condition is called as 'Gout'.
De novo pathway produces ribonucleotides since all the purines produced are synthesized as ribonucleotides (pyrophosphate), but not as free bases. Unlike purines, pyrimidines are synthesised as free bases and later added to ribose sugars. Later deoxyribonucleotides are synthesised from ribonucleotides by the reduction of ribose sugar at C2 position by the intervention of enzymes ribonucleotide reductases.
As discussed above the AMP and GMP are synthesised from Adenine and Guanine by adenine phosphoribosyl transferase (APRT) and hypoxanthine-guanine phosphoribosyl transferase (HGPRT) respectively. Only monophosphates are synthesised through de novo pathway.
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