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TLS Online TPP Program

#Question id: 1384

Mutations that block expression of the E-cadherin gene are thought to be an important step in metastasis. To better understand how loss of E-cadherin contributes to metastasis, scientists created two cell lines that differed in their expression of E-cadherin. One cell line expressed normal E-cadherin, but at 10% of the usual levels. The other cell line expressed normal E-cadherin at the usual levels, and also, at high levels a mutant form that included the cytoplasmic domain but lacked the rest of the protein. Both cell lines exhibited strongly reduced cell adhesion in culture. However, only the cell line with reduced expression of normal E-cadherin metastasized when introduced into mice.

Which of the following hypotheses is most consistent with the observations on cell adhesion and metastasis in these cell lines?

#Unit 4. Cell Communication and Cell Signaling

  1. Loss of E-cadherin releases signalling proteins that normally bind to its cytoplasmic domain, but promote metastasis when free.

  2. The cytoplasmic domain of E-cadherin binds proteins required for cell adhesion, but those proteins are not involved in metastasis.

  3. The E-cadherin transmembrane domain by itself is sufficient to promote the cell–cell adhesion that prevents metastasis.

  4. The loss of adhesion caused by inactivation of E-cadherin is sufficient to explain how E-cadherin mutations promote metastasis.

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TLS Online TPP Program

#Question id: 27075

#Unit 1. Molecules and their Interaction Relevant to Biology

As atom "A" approaches, the electrons of atom "B" will be attracted by the positive end of atom "A". As a result, the electrons of atom "B" will migrate to the left side and make the left side slightly negative. This phenomenon can be explained by 
TLS Online TPP Program

#Question id: 27074

#Unit 1. Molecules and their Interaction Relevant to Biology

Choose the incorrect statement of the following about the Spontaneous dipole-dipole interaction 
TLS Online TPP Program

#Question id: 27073

#Unit 1. Molecules and their Interaction Relevant to Biology

The potential energy of the interaction for the given pair of the image below is represented by the equation
TLS Online TPP Program

#Question id: 27072

#Unit 1. Molecules and their Interaction Relevant to Biology

Choose the incorrect statement regarding the Van der Waals interactions & Hydrogen bonds
1. In Van der Waals interactions greater the area of contact the stronger the interaction.
2. In Van der Waals interactions greater the area of contact the weaker  the interaction.
3. Hydrogen bonds Relative strength is inversely proportional to the polarity More polar atoms form weak H bonds.
4. Hydrogen bonds Relative strength is directly proportional to the polarity More polar atoms form stronger H bonds.
TLS Online TPP Program

#Question id: 27071

#Unit 1. Molecules and their Interaction Relevant to Biology

Bond forces and their strength are given match them correctly 

 Force Strength (kJ/mol) 
 1. Van der Waals interactions a. <40
 2. Hydrogen bonds b. 20
 3. Ionic interactions c. 12–30
 4. Hydrophobic interactions d. 0.4–4.0
TLS Online TPP Program

#Question id: 823

#Unit 1. Molecules and their Interaction Relevant to Biology

chaotropic agents such as guanidinium ion and urea, the efficiency of the chaotropic agent is measured in terms of-