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TLS Online TPP Program

#Question id: 12836

The final layer of control that is critical in the regulation of CDKs is a family of proteins known as CDK inhibitors, or CKIs, which bind directly to the cyclin-CDK complex and inhibit its activity. Which of the following function not done by CKIs?

#Unit 2. Cellular Organization
  1. Binding of INK4s to CDK4 and CDK6 blocks their interaction with cyclin D and hence their protein kinase activity. 
  2. p27 prevents the premature activation of S phase CDKs during G1.
  3. p21CIP plays an important role in the response of metazoan cells to DNA damage by inhibiting G1/S phase CDKs and S phase CDKs, and thereby blocking entry into or passage through S phase.
  4. During ongoing DNA replication and in response to replication stress (slow DNA replication fork movement or DNA replication fork collapse), the ATR-Chk1 protein kinase cascade phosphorylates and inactivates Cdc25C, thereby preventing the activation of mitotic CDKs and inhibiting entry into mitosis.
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TLS Online TPP Program

#Question id: 15441

#Unit 4. Cell Communication and Cell Signaling

In hermaphrodites, expression of the egl-1 gene in the neurons is repressed by the transcription factor, and deletion of that causes these neurons to undergo apoptosis;
TLS Online TPP Program

#Question id: 15369

#Unit 4. Cell Communication and Cell Signaling

Changes in DNA methylation, as well as changes in the activity of histone-modifying enzymes or chromatin-remodeling complexes, are major drivers of tumorigenesis,
a. Hypermethylation of CpG dinucleotides of TSG gene causes cancer.
b. Hypomethylation of CpG dinucleotides of proto-oncogenes causes cancer.
c. SWI/SNF plays a role in repressing the expression of E2F genes.
d. Gain of SWI/SNF function, just like loss of Rb function.
Which of the statements are INCORRECT;
TLS Online TPP Program

#Question id: 15368

#Unit 4. Cell Communication and Cell Signaling

Recent evidence from humans and mice has strongly implicated the SNF5 gene in cancer. The SNF5 protein is a core member of the;
TLS Online TPP Program

#Question id: 15367

#Unit 4. Cell Communication and Cell Signaling

Genes whose protein products stimulate apoptosis behave as tumor suppressors, An example is the PTEN gene, The phosphatase encoded by this gene dephosphorylates phosphatidylinositol 3,4,5-trisphosphate, a secondary messenger that functions in activation of AKT, cells lacking PTEN phosphatase shows; EXCEPT
TLS Online TPP Program

#Question id: 15366

#Unit 4. Cell Communication and Cell Signaling

For pro-proliferation signaling pathways to cause uncontrolled proliferation, as is seen in cancer, this p53 up-regulation must not occur, It is therefore not surprising that p53 is inactive in most human tumors through loss of p53 function itself, down-regulation of positive regulators (PR) of p53 or up-regulation of negative regulators (NR) of p53, these regulators are accordingly
TLS Online TPP Program

#Question id: 15365

#Unit 4. Cell Communication and Cell Signaling

The MDM2 protein in its active form can form a complex with p53, inhibiting the transcription factor and causing p53 ubiquitinylation and subsequent proteasomal degradation, ATM phosphorylates MDM2 to inactivate it, causing increased stabilization of p53, but there is one another gene or key regulator which controls the level of MDM2;