Sickle cell anemia
Q 1 :  Why Sickle cell Anaemia is called as Molecular disease Answer : In DNA There is T -> A mutation in DNA chromosome 11 ( beta chain of 146 amino acids synthesized from chromosome 11 ).. Normally CTC codon  in DNA at 6th position , which is mutated to CAC..  leading to Formation of GAG is replaced to GUG.. GAG code for glutamic acid while GUG code for valine So Gluamic acid replaced by valine leading to sticky patches and sickle cell anaemia  and thrombotic painful crisis at low oxygen