Oncology MCQ - (Dec/03/2006 )

May you please help me with the following 2 questions
im quite confused

1)) Which of the following statements is CORRECT?

a. Point mutations at Codon 12 in the ras gene often result in the production of a protein with increased GTPase activity

b. Point mutations at Codon 12 in the ras gene often result in the production of a protein with decreased GTPase activity

c. Point mutations at Codon 12 in the ras gene often result in the production of a protein with decreased GTP binding activity

d. Point mutations at Codon 12 in the ras gene often result in the production of a protein with increased GTP binding activity




2)) If you found a specific chromosomal deletion in the genome from a tumour, what could be the cause of this specific cancer?



a. The deletion likely affected a tumour-suppressor gene, leading to a loss of function in the tumour cells.

b. The deletion likely affected a proto-oncogene, leading to a loss of function in the tumor cells.

c. The deletion likely affected a tumor-suppressor gene, leading to a gain of function in the tumor cells.

d. The deletion likely affected a proto-oncogene, leading to a gain of function in the tumor cells.


i think 1 - B
2- C

thanks

ras val 12 in mouse or ras val 19 in human are constitutively active proteins
so you're wrong
i think it's D

for q2 : in general deletion are resulting in lost of frame leading to abnormal proteins, 99% shortened by a stop. So the protein is not more active
so it's A....

Hi!

About q2 - A