Q: If a DNA sequence is $5'\text{-}GGATCC\text{-}3'$ and is recognized by the restriction enzyme BamHI, which cuts between the G and G, what are the resulting fragments after digestion?

$5'\text{-}G\ \ \text{and}\ \text{GATCC}-3'$

Question 1

Which of the following best describes the function of a restriction endonuclease in genetic engineering?

Accepted Answer

It recognizes specific DNA sequences and cleaves phosphodiester bonds between adjacent nucleotides.

Question 2

A researcher wants to cut a DNA molecule at a specific sequence. Which property of restriction endonucleases makes this possible?

Accepted Answer

They recognize palindromic sequences in DNA.

Question 3

Which of the following DNA sequences is a palindrome, as recognized by many restriction enzymes?

Accepted Answer

$\mathrm{GAATTC}$

Question 4

EcoRI is a restriction enzyme that recognizes the sequence $\mathrm{GAATTC}$. What is the result of EcoRI acting on the following DNA strand?

$5'	ext{-}GAATTC	ext{-}3'$
$3'	ext{-}CTTAAG	ext{-}5'$

Accepted Answer

It cuts between G and A on both strands, producing sticky ends.

Question 5

Which of the following is NOT a correct statement about restriction endonucleases?

Accepted Answer

They are used to join two DNA fragments together.

Question 6

A scientist uses HindIII to cut a DNA molecule. The recognition sequence for HindIII is $\mathrm{AAGCTT}$. Which of the following best describes the type of ends produced?

Accepted Answer

Sticky ends with single-stranded overhangs

Question 7

If a DNA sequence is $5'	ext{-}GGATCC	ext{-}3'$ and is recognized by the restriction enzyme BamHI, which cuts between the G and G, what are the resulting fragments after digestion?

Accepted Answer

$5'	ext{-}G\ \ 	ext{and}\ 	ext{GATCC}-3'$

Question 8

Which of the following best explains why palindromic sequences are important for restriction enzyme activity?

Accepted Answer

They allow the enzyme to recognize and bind to the same sequence on both DNA strands.

Question 9

A DNA fragment is cut by EcoRI and HindIII. Which of the following best describes the possible outcome?

Accepted Answer

The fragment will have two different sticky ends, one from EcoRI and one from HindIII.

Question 10

In a genetic engineering experiment, why is it important to use the same restriction enzyme to cut both the plasmid vector and the foreign DNA?

Accepted Answer

To ensure compatible sticky ends for ligation.

Question 11

Which of the following is a real-world application of restriction endonucleases?

Accepted Answer

Creating recombinant DNA for insulin production.

Question 12

A student is analyzing a DNA sequence and finds the following:

$5'	ext{-}AAGCTT	ext{-}3'$
$3'	ext{-}TTCGAA	ext{-}5'$

Which restriction enzyme is most likely to recognize and cut this sequence?

Accepted Answer

HindIII

Question 13

Which of the following best describes the difference between sticky ends and blunt ends produced by restriction enzymes?

Accepted Answer

Sticky ends have single-stranded overhangs, while blunt ends are fully base-paired.

Question 14

A forensic scientist is analyzing a DNA sample using restriction fragment length polymorphism (RFLP) analysis. Which step is essential in this process?

Accepted Answer

Digesting DNA with restriction endonucleases to generate fragments.

Question 15

Which of the following is the correct recognition sequence for the restriction enzyme HaeIII?

Accepted Answer

$\mathrm{GGCC}$

Question 16

A DNA molecule is cut with both EcoRI and HindIII. If the original molecule is 10,000 base pairs and EcoRI cuts at 2,000 bp and HindIII at 7,000 bp, what are the sizes of the resulting fragments?

Accepted Answer

$2,000\ \mathrm{bp},\ 5,000\ \mathrm{bp},\ 3,000\ \mathrm{bp}$

Question 17

Which of the following best explains why restriction enzymes are essential tools in molecular cloning?

Accepted Answer

They allow precise cutting and pasting of DNA fragments.

Question 18

A mutation occurs in the recognition site for EcoRI, changing $\mathrm{GAATTC}$ to $\mathrm{GACTTC}$. What is the most likely outcome when EcoRI is added to this DNA?

Accepted Answer

EcoRI will not cut the mutated DNA.

Question 19

Which of the following is a common misconception about restriction endonucleases?

Accepted Answer

They cut DNA at random locations.

Question 20

In a laboratory experiment, a student uses HaeIII to digest a DNA sample. The recognition sequence for HaeIII is $\mathrm{GGCC}$, and it produces blunt ends. Which of the following is a likely challenge when ligating these fragments into a plasmid vector?

Accepted Answer

Blunt ends have no overhangs, making ligation less efficient.

Genetic Engineering: Restriction Endonucleases and DNA Manipulation

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