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BIOCHEmISTRY ``BIOCHEMISTRY—MOlECUlAR BIOCHEmISTRY ``BIOCHEMISTRY—MOlECUlAR SECTION II 35
Nucleotides NucleoSide = base + (deoxy)ribose (Sugar).
NucleoTide = base + (deoxy)ribose + phosphaTe; 5′ end of incoming nucleotide bears the
linked by 3′-5′ phosphodiester bond. triphosphate (energy source for the bond).
Triphosphate bond is target of 3′ hydroxyl
attack.
PURines (A,G)—2 rings. PURe As Gold.
PYrimidines (C,U,T)—1 ring. CUT the PY (pie).
Thymine has a methyl.
Deamination reactions: C-G bond (3 H bonds) stronger than A-T bond
Cytosine uracil (2 H bonds). C-G content melting
Adenine hypoxanthine temperature of DNA. “C-G bonds are like
Guanine xanthine Crazy Glue.”
5-methylcytosine thymine
Amino acids necessary for purine synthesis (cats
Uracil found in RNA; thymine in DNA. purr until they GAG):
Methylation of uracil makes thymine. Glycine
Aspartate
Purine (A, G) Pyrimidine (C, U, T)
Glutamine
CO 2
Carbamoyl Aspartate
Aspartate Glycine phosphate
C N C
N C N C
10
C N –Formyl-
C C tetrahydrofolate C C
N N N
10
N –Formyl- Glutamine
tetrahydrofolate
FAS1_2019_01-Biochem.indd 35 11/7/19 3:16 PM
