Related Experiment Video
Updated: Jun 4, 2026
16:24
Analyzing and Building Nucleic Acid Structures with 3DNA
Published on: April 26, 2013
Topological entropy of DNA sequences
1Department of Mathematics, Pennsylvania State University, State College, PA 16801, USA. koslicki@math.psu.edu
Bioinformatics (Oxford, England)
|February 15, 2011
Summary
We developed a new method to calculate topological entropy, overcoming previous limitations. Our findings reveal introns have higher entropy than exons, but are less random than anticipated, with unique patterns in chromosome Y introns.
Area of Science:
- Genomics
- Information Theory
- Bioinformatics
Background:
- Topological entropy calculations are challenging due to finite sample effects and high dimensionality.
- Previous studies suggested higher exon entropy than intron entropy, implying greater exon randomness.
Purpose of the Study:
- To introduce a novel, robust approximation for topological entropy.
- To analyze genomic sequences, specifically human introns and exons, using this new method.
Main Methods:
- Developed a new approximation for topological entropy, addressing prior implementation difficulties.
- Computed the expected value of this new topological entropy approximation.
- Applied the definition to intron and exon regions of the human genome.
Main Results:
- Intron entropy is significantly higher than exon entropy, contradicting some previous findings.
- Introns exhibit lower randomness than expected, with entropy below the computed expected value.
- Chromosome Y introns display atypical, bimodal entropy, suggesting potential functional or structural variations.
Conclusions:
- The new topological entropy approximation provides a more reliable measure for genomic sequence analysis.
- Genomic sequence complexity differs between introns and exons, with introns possessing unexpected structural properties.
- Chromosome Y introns warrant further investigation due to their unique entropy characteristics.
Related Concept Videos
02:02DNA Topoisomerases
Topoisomerases are enzymes that relax overwound DNA molecules during various cell processes, including DNA replication and transcription. These enzymes regulate positive and negative DNA supercoiling without changing the nucleotide sequence. DNA overwinding in a clockwise direction results in positively supercoiled DNA, whereas underwinding in a counterclockwise direction produces negatively supercoiled DNA.
Types and Mechanism of action
Topoisomerases are divided into two main types. Type I...
Types and Mechanism of action
Topoisomerases are divided into two main types. Type I...
01:22Entropy within the Cell
A living cell's primary tasks of obtaining, transforming, and using energy to do work may seem simple. However, the second law of thermodynamics explains why these tasks are harder than they appear. None of the energy transfers in the universe are completely efficient. In every energy transfer, some amount of energy is lost in a form that is unusable. In most cases, this form is heat energy. Thermodynamically, heat energy is defined as the energy transferred from one system to another that is...
02:39Entropy
Salt particles that have dissolved in water never spontaneously come back together in solution to reform solid particles. Moreover, a gas that has expanded in a vacuum remains dispersed and never spontaneously reassembles. The unidirectional nature of these phenomena is the result of a thermodynamic state function called entropy (S). Entropy is the measure of the extent to which the energy is dispersed throughout a system, or in other words, it is proportional to the degree of disorder of a...
01:18Entropy
The first law of thermodynamics is quantitatively formulated via an equation relating the internal energy of a system, the heat exchanged by it, and the work done on it. A quantitative formulation of the second law of thermodynamics leads to defining a state function, the entropy.
When an ideal gas expands isothermally, the disorder in the gas increases. From the molecular perspective, the gas molecules have more volume to move around in.
Consider an infinitesimal step in the expansion, which...
When an ideal gas expands isothermally, the disorder in the gas increases. From the molecular perspective, the gas molecules have more volume to move around in.
Consider an infinitesimal step in the expansion, which...
01:19The Nucleosome
Human DNA is almost two meters long. However, it is compressed inside a tiny nucleus measuring only a few microns in diameter. To make this degree of compaction possible, DNA is organized into several sequential levels so that it can fit into such a tiny space. The most compact form of DNA is a chromosome that can be seen under a microscope in a dividing cell.
In a chromosome, DNA is wound twice around a protein complex called a histone octamer core, which consists of 8 histone proteins. This...
In a chromosome, DNA is wound twice around a protein complex called a histone octamer core, which consists of 8 histone proteins. This...
02:33The Nucleosome
DNA in a human cell is almost 2m long and it is packed inside a tiny nucleus that is only a few microns in diameter. The level of compaction of DNA inside the nucleus is astonishing. It is organized into several sequentially higher levels of compaction to fit into such a tiny space. The most compact form of DNA is a chromosome that can be seen under a microscope in a dividing cell.
DNA is wound twice around a protein complex called histone core, that consist of 8 histone proteins. This complex...
DNA is wound twice around a protein complex called histone core, that consist of 8 histone proteins. This complex...