Difference between Single-Strand Break and Double-Strand Break

Single-Strand Break

DNA (dsDNA) is a double-stranded helical structure. Any damage or break at one of the strands is termed a single-strand break. Here, the nucleotide sequence of only one strand is altered. It breaks the whole sugar-phosphate backbone of the DNA. This type of DNA damage is the most common one. Factors such as UV rays, radiations, chemicals, etc can cause this damage.

Double-Strand Break

It is the less common type of DNA break seen in organisms. Here, both the strands of the DNA are altered or broken. This also results in the breaking of the sugar-phosphate backbone. It is difficult to repair this damage by normal cellular mechanisms. Thus, they can also be lethal. The broken strands can lead to mutations and health issues.

Also Read: Double Helix Structure of DNA

Difference between Single-Strand Break and Double-Strand Break

Single-Strand Break

Double-Strand Break

It is the damage that happens in one strand of the dsDNA.

It is the damage that happens in both the strands of the dsDNA.

It is the most common type of DNA break and has a high frequency of occurrence.

It is a comparatively rare phenomenon.

It can be easily restored using a DNA repair mechanism.

This damage cannot be easily repaired.

This break may not cause any adverse effects.

This break can lead to lethal diseases.

Frequently Asked Questions on Difference between Single-Strand Break and Double-Strand Break

What is a DNA repair mechanism?

The process by which DNA restores its integrity is termed a DNA repair mechanism. In a single-strand break, the undamaged strand can be used as a template to correct the damage. In the double-strand break, homologous recombination happens as a common repair mechanism. Here, the genetic material is exchanged between two identical DNA molecules. Chemicals can also be used to reverse the damage.

What happens with the accumulation of DNA damage?

A large accumulation of DNA damage is difficult to reverse by repair mechanisms. Thus, the cell can undergo senescence or complete dormancy by terminating cell division. Also, cell suicide or apoptosis is the most common possibility. Sometimes, the unregulated proliferation of these damaged DNA can also lead to cancer.

Extended Reading: Difference between Gene and DNA

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