Blunt Ends MCQ Questions and Answers

1. What are blunt ends in DNA molecules?

A. DNA ends with no single-stranded overhang

B. DNA ends with long RNA overhangs

C. DNA ends containing only adenine bases

D. DNA ends joined by hydrogen bonds

Correct Answer:
DNA ends with no single-stranded overhang

Explanation:
Blunt ends are formed when both DNA strands are cut at the same position, leaving no single-stranded nucleotide overhang.

2. How are blunt ends produced in double-stranded DNA?

A. By cutting both strands at the same position

B. By cutting only one strand of DNA

C. By adding extra nucleotides to one strand

D. By removing all bases from both strands

Correct Answer:
By cutting both strands at the same position

Explanation:
A restriction enzyme produces blunt ends when it makes cuts directly opposite each other in the two DNA strands.

3. Which type of DNA end lacks a single-stranded overhang?

A. Blunt end

B. Sticky end

C. Cohesive end

D. Poly-A end

Correct Answer:
Blunt end

Explanation:
Blunt ends have no unpaired single-stranded nucleotides projecting from either DNA strand.

4. Which restriction enzyme is commonly known for producing blunt ends?

A. SmaI

B. EcoRI

C. HindIII

D. BamHI

Correct Answer:
SmaI

Explanation:
SmaI cuts both DNA strands at the same position in its recognition sequence, producing blunt ends.

5. What is a major feature of DNA fragments with blunt ends?

A. Their ends can pair without complementary overhangs

B. Their ends always contain thymine overhangs

C. Their ends can pair only with RNA ends

D. Their ends contain permanently exposed codons

Correct Answer:
Their ends can pair without complementary overhangs

Explanation:
Blunt-ended DNA fragments do not have overhangs, so they cannot base-pair through complementary sticky ends.

6. Which enzyme can join two DNA fragments having blunt ends?

A. DNA ligase

B. DNA helicase

C. RNA polymerase

D. DNA gyrase

Correct Answer:
DNA ligase

Explanation:
DNA ligase joins blunt-ended DNA fragments by forming phosphodiester bonds between adjacent nucleotides.

7. Compared with sticky ends, blunt ends generally require what for efficient joining?

A. Closer contact and suitable ligation conditions

B. A single-stranded RNA primer only

C. Removal of both DNA strands

D. Conversion into proteins

Correct Answer:
Closer contact and suitable ligation conditions

Explanation:
Blunt ends lack complementary overhangs, so DNA ligase must join them without the temporary base pairing provided by sticky ends.

8. What is absent at the ends of a blunt-ended DNA fragment?

A. Single-stranded nucleotide overhang

B. Double-stranded DNA region

C. Phosphodiester bond within each strand

D. Nitrogenous bases in the DNA

Correct Answer:
Single-stranded nucleotide overhang

Explanation:
A blunt-ended fragment has flush DNA ends and therefore does not possess a single-stranded overhang.

9. If a restriction enzyme cuts both DNA strands exactly opposite each other, what type of ends are formed?

A. Blunt ends

B. Sticky ends

C. Cohesive RNA ends

D. Circular ends

Correct Answer:
Blunt ends

Explanation:
Cuts made at directly opposite positions leave flush ends, which are called blunt ends.

10. Which statement about blunt-ended DNA fragments is correct?

A. They can be joined by DNA ligase

B. They always have complementary overhangs

C. They are made only from single-stranded DNA

D. They cannot be joined under any condition

Correct Answer:
They can be joined by DNA ligase

Explanation:
DNA ligase can join blunt-ended fragments by creating phosphodiester bonds, although joining is usually less efficient than with compatible sticky ends.

biology : class12
Blunt Ends : DNA Isolation, Restriction Enzymes, Vector, Ligation, Host Cell : Recombinant DNA Technology
MCQ Questions and Answers

Short Questions and Answers

biology : class12Blunt Ends : DNA Isolation, Restriction Enzymes, Vector, Ligation, Host Cell : Recombinant DNA Technology MCQ Questions and Answers

Short Questions and Answers

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biology : class12
Blunt Ends : DNA Isolation, Restriction Enzymes, Vector, Ligation, Host Cell : Recombinant DNA Technology
MCQ Questions and Answers