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TLS Online TPP Program

#Question id: 18732

Mechanism of ligation for both T4 DNA ligase and E. coli DNA ligase makes use of Adenosine Monophosphate (AMP). Which of the steps is involved in the ligation mechanism?

#Unit 13. Methods in Biology
  1. AMP is added to the 5’ phosphate of one of the DNA molecules
  2. It leads to the liberation of pyrophosphate from NAD and nicotinamide mononucleotide from ATP
  3. The AMP is further displaced by an electrophilic attack
  4. The AMP is further displaced by nucleophilic attack by 3’ hydroxyl of the same DNA molecule
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TLS Online TPP Program

#Question id: 1076

#Unit 4. Cell Communication and Cell Signaling

Why are viroids resistant to nucleases?
TLS Online TPP Program

#Question id: 1077

#Unit 4. Cell Communication and Cell Signaling

Would ID50 and LD50 necessarily be the same for a given virus? Why or why not?
TLS Online TPP Program

#Question id: 1078

#Unit 4. Cell Communication and Cell Signaling

Which of the following statements about interferon is incorrect?
TLS Online TPP Program

#Question id: 1079

#Unit 4. Cell Communication and Cell Signaling

Smoking impairs the ciliated cells of the middle portion of the respiratory tract. Many analgesic drugs (painkillers) impair peristalsis (the churning motion of the digestive tract). The result of either of these activities leads to an increased risk of infection in their respective areas. Why?
TLS Online TPP Program

#Question id: 1080

#Unit 4. Cell Communication and Cell Signaling

 In the formation of biofilms, such as those forming on unbrushed teeth, cell signaling serves which function?
TLS Online TPP Program

#Question id: 1081

#Unit 4. Cell Communication and Cell Signaling

Which of the following is a type of local signaling in which a cell secretes a signal molecule that affects neighboring cells?