Question

Which ONE of the following is NOT TRUE about BCR-ABL:

a)ABL is a tyrosine kinase in the Src family

b)the translocation is caused by bimolane, a topoisomerase inhibitor, used as a medical treatment in China

c)the fusion protein is oncogenic because BCR retains ABL in the cytoplasm where it phosphorylates new substrates

d)it is a fusion protein created by a reciprocal translocation found in chronic myelogenous leukemia

e)the translocated chromosome is referred to as the Philadelphia chromosome

When Cas9 finds the specific DNA sequence, specified by the guide RNA, it:

a)Methylates the DNA

b)Acetylates the DNA

c)Phosphorylates the DNA

d)Turns the DNA inside out

e)Causes a dsDNA break

Answer 1

Question 1 : Answer A is not true

ABL is a tyrosine kinase which belong to ABL family . It acts as a substrate for Src signalling in normal cells . Src kinase family consists of 9 members ( Src,Yes,Fyn,Fgr , Lck,Hck, Blk,Lyn,Frk).

BCR- ABL is a fusion protein created by reciprocal translocation, seen in most of the chronic myelogenous leukemia patients. BCR ABL gene is a mutation formed by fusion of BCR and ABL genes. Usually BCR occurs on chromosome number 22 and ABL occurs on chromosome number 9. The fusion protein is oncogenic because BCR retains ABL in the cytoplasm where it phosphorylates new substrates .

The translocated chromosomes are called Philadelphia chromosomes.Topoisomerase inhibitors cause this translocation and the bimolane , a topoisomerase inhibtor ll are used in China for treatment.

Question 2 : Answer : E

Cas 9 enzyme recognise the specific DNA sequence with the help of RNA and attach to the Target DNA sequence. After binding, they cut the double stranded DNA at target sites ( 3-4 nucleotides).