This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Molecular Genetics, Subject name: Biochemistry
Haemoglobin synthesis starts with? 
Select and explain. 
A. Glycine, B. Histidine, C. Iron, D. Folic acid
A: Glycine
Answer: A: Glycine 
Explanation: ANSWER: (A) GlycineREF: Harper 26th e p. 271-275Steps of porphyrin ring synthesis:EnzymeLocationSubstrateProductporphyriaALA synthaseMitochondrionGlycine, sucdnyl CoAD-Aminolevoilinic acidnoneALA dehydrataseCytosolD-Aminolevulinic acidPorphobilinogenALA-DehydratasedeficiencyPEG deaminaseCytosolPorphobilinogenHydroxymethyl bilaneAcuteintermittentporphyriaUroporphyrinogen III synthaseCytosolHydroxymethyl bilaneUroporphyrinogen IIICongenitalerythropoieticporphyriaUroporphyrinogen III decarboxylaseCytosolUroporphyrinogen IIICoproporphyrinogen IIIPorphyria cutanea tardaCoproporphyrinogen III oxidaseMitochondrionCoproporphvrinogen IIIProtoporphyrinogen IXCoproporphyriaProtoporphyrinogenoxidaseMitochondrionProtoporphyrmogen IXProtoporphyrin IXVariegateporphyriaFerrochelataseMitochondrionProtoporphyrin IXHemeErythropoieticprotoporphyriaHeme synthesis--note that some reactions occur in the cytoplasm and some in the mitochondrion (yellow)