Biochemistry USMLE step 1 Questions and Answers 100% Correct

"elfin" facies, ID, hypercalcemia (↑ Vit. D sensitivity), verbal & musical ability, extreme friendlinessWilliams syndrome "mewing," microcephaly, ID, VSDcri-du-chat syndrome (Debranching enzyme) (Myophosphoeylase) ↑ glycogen in muscle→ painful muscle cramps, myoglobinuria (red urine) with strenuous exercise, arrhythmia normal blood glucoseGlycogen Storage Disease type V (McArdle) ↑ HDL in a very unhealthy personEtOH → ↑ HDL synthesis ↑ nuchal translucency and hypoplastic nasal bone on first-trimester USDown syndrome ↑ urine homocysteine, ID, osteoporosis, marfanoid habitus & kyphotic, lens subluxation, atherosclerosis + thrombosishomocystinuria due to 1. homocysteine methyltransferase deficiency 2. cystathionine synthase def. 3. decreased affinity of cystathionine synthase for pyridoxal phosphate ↓ hydroxylation of collagen proline and lysine residues in the RERvitamin C deficiency → scurvy 2,4 dinitrophenol 2. Annealing, sticking DNA primer to each copy by cooling 3 cell cycle regulatorscyclins CDKs (cyclin-dependent kinases) tumor suppressors 3 vesicular trafficking proteins