Question

Identify the incorrect statement regarding restriction endonuclease

• A. The enzyme recognizes a specific palindromic nucleotide sequence in the DNA.
• B. The enzyme cuts DNA molecules at the identified position within the DNA.
• C. The enzyme binds DNA at specific sites and cuts only one of the two strands.
• D. The enzyme cuts the sugar-phosphate backbone at specific sites on each strand.

Answer 1

The correct option is C

The enzyme binds DNA at specific sites and cuts only one of the two strands.

The correct option is C.

The explanation for the correct option:

Option C:

1. Enzymes called endonucleases cleave the phosphodiester bond found in polynucleotide chains.
2. Deoxyribonuclease I is one enzyme that generally randomly cuts DNA, while many others—often referred to as restriction endonucleases or restriction enzymes—only cleave at extremely particular nucleotide sequences.
3. By identifying a certain sequence, restriction enzymes cut DNA molecules at a specific location.
4. To work, each restriction endonuclease measures the length of a DNA sequence.
5. It will connect to the DNA and cut each of the two strands of the double helix at particular locations in their sugar-phosphate backbone once it locates its unique recognition sequence.

The explanations for the incorrect options:

Option A:

1. Because DNA is double-stranded, the enzyme has "two sides" to which it can attach.
2. A palindromic sequence is the same on both sides when read backward and forwards.
3. This indicates that regardless of how the enzyme approaches the DNA, it can recognize the sequence.
4. The DNA contains a unique palindromic nucleotide sequence that each restriction endonuclease can recognize.
5. The majority of restriction enzymes can detect palindromic sequences, in which the sequences of both DNA strands are identical when read from 5′ to 3′.

Option B:

1. Restriction endonucleases, another name for restriction enzymes, identify a particular pattern of nucleotides in double-stranded DNA and make a precise cut in the DNA.
2. They are essential for the separation of genes and the creation of DNA molecules used in cloning.
3. A restriction enzyme functions via shape-to-shape matching, just like all other enzymes.
4. The enzyme wraps around the DNA and breaks both of the DNA strands when it comes into contact with a DNA sequence that has a shape that matches a recognition site on the enzyme.

Option D:

1. The sugar-phosphate backbone of double-stranded DNA is cut by restriction enzymes.
2. They recognize a particular location on the double-stranded DNA and break it there or nearby.
3. The use of restriction enzymes is crucial in molecular biology.
4. An enzyme is known as a restriction enzyme, restriction endonuclease, or restricts cleaves DNA into fragments at or close to particular recognition areas inside molecules called restriction sites.

Final answer: The incorrect statement regarding restriction endonuclease is (C).