Question

QUESTION 15

1. Which of the following is NOT TRUE about the Rb pathway:

   		Rb is a tumor suppressor originally identified in retinoblastomas
   		Alfred Knudson noted that retinoblastomas can occur in either an inherited or a sporadic fashion in the 1960s
   		RB was cloned in the 1980s, after p53 was identified
   		Only young children develop retinoblastomas
   		RB is phosphorylated by CDKs, preventing binding to E2F

2 points   

QUESTION 16

1. Which of the following is NOT TRUE about p53:

   		in tumors lacking RB, p53 expression is high
   		it was originally thought to be an oncogene
   		it was first identified as binding to the human papilloma virus E7 protein
   		it is the most commonly mutated gene in human cancer
   		it is considered to be guardian of the genome

2 points   

QUESTION 17

1. Which ONE of the following is TRUE about “knock-out” & “knock-down” technologies

   		A knock-out of a tumor suppressor gene can cause cancer, while a knock-down cannot
   		A knock-out is a physical modification to the genome, while a knock-down affects only gene expression
   		There is no difference, they are just two different ways to describe genetic manipulation of the genome
   		A knock-out of an oncogene can cause cancer, while a knock-down cannot
   		A knock-out can be reversed and controlled, while a knock-down is a permanent modification

2 points   

QUESTION 18

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

   		the fusion protein is oncogenic because BCR retains ABL in the cytoplasm where it phosphorylates new substrates
   		the translocation is caused by bimolane, a topoisomerase inhibitor, used as a medical treatment in China
   		ABL is a tyrosine kinase in the Src family
   		the translocated chromosome is referred to as the Philadelphia chromosome
   		it is a fusion protein created by a reciprocal translocation found in chronic myelogenous leukemia

2 points   

QUESTION 19

1. Which ONE of the following is NOT TRUE about PML-RAR:

   		the translocation is caused by ionizing irradiation and found in Hiroshima and Nagasaki victims
   		it is a fusion protein created by a reciprocal translocation found in acute promyelocytic leukemia
   		the fusion protein retains the ability of the retinoic acid receptor (RAR) to bind retinoic acid and DNA
   		PML contains zinc fingers and a coiled-coil domain, which are important for maintaining the structure of nuclear bodies

2 points   

QUESTION 20

1. The CRISPR-Cas9 is a genome editing system. It was first discovered as…

   		The defense mechanism in bacteria against bacteriophages
   		The defense mechanism in bacteria against humans
   		The defense mechanism in zebrafish against bacteria
   		The defense mechanism in bacteria against macrophages
   		The defense mechanism in zebrafish against sharks

Answer 1

15. Option E, RB is phosphorylated by CDKs, preventing binding to E2F

Explanation –

When Rb undergoes phosphorylation, it becomes more site-specific. It is phosphorylated

by Cdk in cycling cells to promotes protein-protein interactions by creating a phospho-epitope that gets structured when it binds to its targets.

16. Option A, in tumors lacking RB, p53 expression is high

Explanation-

In cancerous cells, the human genome p53 is deactivated. The major function of p53 genome is to suppress tumours thereby allowing it to grow.

17. Option B, A knock-out is a physical modification to the genome, while a knock-down affects only gene expression

Explanation –

In the process of gene knockout, no gene is expressed while in knock down the gene expression is reduced. In Knockout, the gene is completely silenced while in knockdown some protein is still made to express the gene partially.

18. Option B, the translocation is caused by bimolane, a topoisomerase inhibitor, used as a medical treatment in China

Explanation-

Reciprocal translocation is caused by Philadelphia chromosome to fuse chromosomes 9 and 22 to join ABL1 on chromosome 9 and BCR on chromosome 22.