QUESTION 18

Briefly describe why E. coli wants toexpress different amounts of the lac operon genes in relation tothe presence/absence of glucose and lactose and themolecular mechanism by which it does so for eachof the four conditions with respect to glucose and lactose.

QUESTION 19

A rare deletion on the long arm of chromosome15 (15q11-13) produces one of two types of genetic disorders inhumans.  These are Prader-Willi syndrome (obesity,hypotonia, hypogonadism) and Angelman syndrome (epilepsy, tremors,perpetual smiling).  Three imprinted genes are present inthe deleted region.  These are snrpn andndn (lack of which is associated with Prader-Willi) andube3A (lack of which is associated withAngelman).  snrpn and ndn arepaternally imprinted for expression and ube3A ismaternally imprinted.   Charlie and Pat are siblingsboth with Angelman syndrome and Charlie has one (of two) child withPrader-Willi Syndrome while Pat has a child with Angelmansyndrome.  What are the sexes of Charlie andPat?  Explain your answer.  Can Charlie and Pathave two normal parents or does one of them have Prader-Willi orAngelman syndrome.  Explain your answer and if one ofthem has a disorder tell me which parent had which disorder.