TLS Online TPP Program

#Question id: 7150


What is the role of semaphorins and Eph ligands in development of the nervous system?

#Unit 5. Developmental Biology
  1. The semaphorins and Eph ligands are growth factors that stimulate cell division of neurons.
  2. The semaphorins and Eph ligands act as signals for the outgrowth of neuronal growth cones; in general, both lead growth cones to turn away.
  3. The semaphorins and Eph ligands act as signals for the outgrowth of neuronal growth cones; in general, both lead growth cones to come toward them.
  4. The semaphorins and Eph ligands are cell-cell adhesion molecules that bind adjacent neurons together.
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TLS Online TPP Program

#Question id: 4531

#Unit 3. Fundamental Processes

Specific elements called insulators control the actions of activators. When placed between an enhancer and a promoter,

TLS Online TPP Program

#Question id: 4532

#Unit 3. Fundamental Processes

Locus control region, or LCR,

TLS Online TPP Program

#Question id: 4533

#Unit 3. Fundamental Processes

When multiple activators work together, they often do so synergistically. That is, the effect of

TLS Online TPP Program

#Question id: 4534

#Unit 3. Fundamental Processes

The yeast Saccharomyces cerevisiae divides by budding: instead of dividing to produce two identical daughter cells, the so-called mother cell buds to produce a daughter cell, The HO gene is expressed only in mother cells and only at a certain point in the cell cycle,

1. SBF

I- Which is active only during the G1-S transition of the cell cycle.

2. SWI5

II-Which acts only in the mother cell.

III- Recruit nucleosome modifiers

TLS Online TPP Program

#Question id: 4535

#Unit 3. Fundamental Processes

The activators bind—and the enhanceosome forms—in a highly cooperative manner, ensuring that all three activators must be present. The following are three ways the regulators might be binding cooperatively:

I- Through direct protein–protein interactions between them

II- By changes in the DNA caused by binding of one protein helping binding of another;

III- By the fact that the activators all interact simultaneously with the coactivator.

TLS Online TPP Program

#Question id: 4536

#Unit 3. Fundamental Processes

The human b-interferon gene is activated in cells upon viral infection through some activators, EXCEPT one