Mode of Action of Nucleases

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What is the primary activity of Nuclease Bal 31 enzyme?

A DNA-dependent RNA polymerase
A 5' exonuclease
A slow-acting endonuclease
A fast-acting 3' exonuclease (correct)

Which enzyme generates molecules with protruding 5' termini?

Exonuclease III (correct)
Nuclease Bal 31
DNase I
Nuclease S1

What type of nucleic acid template does a DNA-dependent DNA polymerase use?

RNA
mRNA
tRNA
DNA (correct)

Why is it essential to avoid RNase contamination in preparing recombinant DNA?

To prevent cDNA preparation from an mRNA template (A) Signup and view all the answers

In what direction does DNA synthesis proceed in the presence of a polymerase enzyme?

5'-3' (D) Signup and view all the answers

What type of bond is formed during nucleic acid synthesis?

Phosphodiester bond (A) Signup and view all the answers

What is the function of a DNA-dependent RNA polymerase?

Transcribes DNA into RNA (A) Signup and view all the answers

Why is it necessary to wear gloves and treat equipment to avoid ribonuclease contamination?

To prevent RNase secretion in sweat (C) Signup and view all the answers

What is the main function of the enzyme mentioned in the first paragraph?

To copy mRNA molecules for cloning (A) Signup and view all the answers

What is the purpose of using alkaline phosphatase in certain cloning procedures?

To prevent unwanted ligation of DNA molecules (A) Signup and view all the answers

What is the function of polynucleotide kinase?

To add radioactive phosphate to DNA ends (A) Signup and view all the answers

What is the main function of terminal transferase?

To add nucleotides to the 3' ends of DNA molecules (A) Signup and view all the answers

What is the main function of DNA ligase?

To repair broken phosphodiester bonds (D) Signup and view all the answers

What is the purpose of using terminal transferase in the construction of recombinants?

To add homopolymer tails to DNA molecules (A) Signup and view all the answers

What is the primary function of reverse transcriptase in genetic engineering?

To synthesize a DNA copy of an mRNA molecule (C) Signup and view all the answers

What is the purpose of removing the 5'-3' exonuclease function from DNA polymerase I?

To produce a modified form of DNA polymerase for specific applications (A) Signup and view all the answers

What is DNA ligase often referred to as?

Molecular glue (D) Signup and view all the answers

What is the Klenow fragment used for?

All of the above (D) Signup and view all the answers

What is the primary function of DNA ligase in genetic engineering?

To seal discontinuities in the sugar-phosphate chains (C) Signup and view all the answers

What activity is suppressed under normal reaction conditions for the Klenow fragment?

3'-5' exonuclease activity (D) Signup and view all the answers

Which type of DNA molecules can DNA ligase join under appropriate conditions?

Both cohesive-ended and blunt-ended DNA molecules (D) Signup and view all the answers

What is the function of phosphatases, kinases, and transferases in genetic engineering?

To modify the ends of DNA molecules (C) Signup and view all the answers

What is the optimal temperature for DNA ligase to work at?

37°C (D) Signup and view all the answers

What is the primary difference between DNA polymerase I and the Klenow fragment?

The Klenow fragment lacks 5'-3' exonuclease activity (D) Signup and view all the answers

Why is DNA ligase often used at lower temperatures than its optimal temperature?

To prevent thermal denaturation of the short base-paired regions (C) Signup and view all the answers

What is the role of DNA polymerase I in the nick translation procedure?

To radiolabel DNA (C) Signup and view all the answers

What technology is used to amplify DNA molecules in vitro?

PCR (B) Signup and view all the answers

What is the characteristic of reverse transcriptase that distinguishes it from other DNA polymerases?

It has no associated exonuclease activity (D) Signup and view all the answers

What is the purpose of DNA ligase in genetic engineering?

To join DNA molecules together (A) Signup and view all the answers

What is the relationship between DNA ligase and restriction enzymes?

DNA ligase and restriction enzymes are used together to cut and join DNA molecules (C) Signup and view all the answers