Nucleotides – Purine and Pyramidine Synthesis and degradation
- PURines (A, G)—2 rings. (PURe As God)
- PYrimidines (C, T, U)—1 ring. (CUT the PY (pie))
- Thymine has a methyl group .
- Deamination of cytosinemakes uracil.
- Uracil found in RNA; thymine in DNA.
- G-C bond (3 H bonds) stronger than A-T bond (2 H bonds).
- ↑ G-C content →↑ melting temperature of DNA.
- GAG—Amino acids necessary for purine synthesis:
- NucleoSide= base + (deoxy)ribose (Sugar).
- NucleoTides = base + (deoxy)ribose + phosphaTe; linked by 3′-5′phosphodiesterbond.
A Pentose with a 5′ phosphate group, a 2′ OH group and 1′ pyrimidine group describes which of the following structures ?
- a) Cytosine
- b) Thymidine
- c) Thymidylate
- d) Cytidylate
- e) Guanosine
- De novo pyrimidine and purine synthesis
- Purines :
- Start with sugar + phosphate (PRPP)
- Add base
- Pyrimidines :
- Make temporary base (orotic acid)
- Add sugar + phosphate (PRPP)
- Modify bas
Ribonucleotides are synthesized first and are converted to deoxyribonucleotides by ribonucleotidereductase.
Carbamoyl phosphate is involved in 2 metabolic pathways: de novo pyrimidine synthesis and the urea cycle