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TLS Online TPP Program

#Question id: 1513

The kinase activity of ATM is activated in response to DNA damage due to various stresses (e.g., UV irradiation, heat). Activated ATM then triggers following pathways leading to arrest in G1.

A. Chk2 is phosphorylated and, in turn, phosphorylates Cdc25A, thereby marking it for degradation and blocking its role in CDK2 activation.

B. Phosphorylation of p53 stabilizes it, permitting p53-activated expression of genes encoding proteins that cause arrest in G1, promote apoptosis, or participate in DNA repair.

C. Controlling the pool of p53, ATM phosphorylates MDM2 to inactivate it, causing increased stabilization of p53. Another protein p14ARF inhibits the activity of Mdm2 thus stabilizing p53.

Based on the above information, which one of the following statements is correct?

#Unit 4. Cell Communication and Cell Signaling

  1. Gain-of-function of p14ARF and Loss-of-function of p53 leads to tumor formation.

  2. Gain-of-function of p53 and Loss-of-function of Chk2 leads to tumor formation.

  3. Gain-of-function of Cdc25A and Loss-of-function of Chk2 leads to tumor formation.

  4. Gain-of-function of Chk2 and Loss-of-function of MDM2 leads to tumor formation.

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TLS Online TPP Program

#Question id: 12062

#Unit 7. System Physiology – Animal

Mass movements are often stimulated after a meal by distention of the stomach (gastrocolic reflex) and distention of the duodenum (duodenocolic reflex). Mass movements often lead to which of the following?
TLS Online TPP Program

#Question id: 1388

#Unit 4. Cell Communication and Cell Signaling

When Lucifer yellow, a small dye, is injected into a neuron of the retina, neighboring neurons become rapidly labeled. If the retina is incubated in dopamine prior to Lucifer yellow injection, only the injected neuron becomes labeled. These findings suggest which of the following?

I. Neurons of the retina communicate via gap junctions.

II. Dopamine is transferred between cells via gap junctions.

III. Dopamine decreases the permeability of gap junctions.
TLS Online TPP Program

#Question id: 5171

#General Aptitude

Which of the following is the largest ? 
TLS Online TPP Program

#Question id: 18796

#Unit 13. Methods in Biology

Newly replicating cell can be selectively killed by photolysis incorporating 
TLS Online TPP Program

#Question id: 871

#Unit 1. Molecules and their Interaction Relevant to Biology

According to ‘Energy–entropy phenomenon’ for protein folding correct combinations of possible conformations

1. Unfolded polypeptide

a. high-energy, high-entropy

2. Native conformation

b. low-energy, low-entropy

3. False energy minima

c. modest-energy, low-entropy