Biological Topics
Learn more about the structure of DNA and much more.
We have compiled some biological topics for you below. Among other things, you will learn how DNA is structured or how a variant occurs.
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Interesting Facts about Biological Topics
Genetics deals with the theory of inheritance. The genome is the entirety of genetic information that is passed on to us from our mother and father. This information determines our appearance and characteristics, but also possible predispositions to diseases. DNA (desoxyribonucleic acid) is the carrier of genetic information and is built from a double helix, which consists of a sequence of four different basic building blocks (the bases A, C, G and T). The sequence of the basic building blocks encodes the information. In total, human DNA consists of around three billion base pairs and codes for around 23,000 genes. A gene is a section of the genome that encodes a functional unit, e.g. a protein. Proteins are responsible for the structure of the cell and metabolism. In genetics, DNA can therefore be analyzed to find out which inherited genomic changes can possibly hold a higher risk for diseases.
A gene is a section of DNA, that encodes the blueprint of a protein. The production of a protein takes place in two steps, transcription and translation. In the cell nucleus, where the DNA is stored, a copy of a single strand of the gene can be produced, the RNA. The RNA can be transported out of the cell nucleus, where the information can be used to produce the protein. Proteins can fulfill a wide variety of functions in the cell, such as structure maintenance, transport, or decomposition of nutrients. If a gene is altered by a variant, this can affect the structure and therefore also the function of the protein. For example, if a variant leads to an altered protein in the glucose metabolism, sugar is more difficult to process which can lead to diabetes. Early detection of changes in the gene can delay or prevent a possible effect of the gene variant through individual measures.
The genome comprises the whole genetic information of a cell. It contains so-called coding and non-coding regions, the exons and the introns. Coding regions are those areas of the DNA which, simply put, represent the building instruction for a specific protein that can be produced in the cell. On the other hand, the introns do not code for proteins, but e.g. have regulatory functions. When talking about the exome, we refer to the sum of all areas on the DNA that code directly for the production of proteins.
In diagnostics, the exome is preferable to the genome, as the focus on the disease-relevant areas allows more precise statements to be made. Coverage can be used to describe how precise the analysis is. It is a measure of the number of DNA sequences that cover a specific target region. If the same base was identified particularly often at the same location, the coverage is high. It can therefore be said with high probability that the sequencing at this location provides a correct result.
For the exome diagnostics at CeGaT, we have developed our own analysis, which covers the classical exome parts but also considers all other disease-causing regions in the genome. This provides the ideal basis for comprehensive and reliable genetic diagnostics.
A hotspot is a location on a gene that is particularly susceptible to variants. On average, gene variants are present at these sites more frequently. These can either be inconspicuous and have no consequences, or they can lead to diseases. It is therefore important to look at these regions in a preventive genetic analysis. However, as other sites within the gene can also be affected, we at CeGaT analyze the entire gene and not just the hotspots with great care. In this way, we also detect variants that lie outside the hotspot areas and thus offer a very comprehensive analysis.
Changes in the DNA can occur on different levels. During cell division, entire areas can be exchanged between chromosomes or individual chromosomes can be duplicated or missing. One example of this is trisomy 21, also known as Down’s syndrome, in which chromosome 21 is present in triplicate. Changes in the DNA can also be a difference in the sequence of the individual DNA building blocks within a gene. This can lead to the respective cell components encoded not being formed correctly and thus cause a disease. Environmental influences such as UV radiation can also lead to changes in the DNA if it is not properly repaired after being damaged by UV radiation. Acquired variants like these can also cause diseases such as tumors.
An enzyme is a protein that can accelerate a biochemical reaction in our body. Enzymes are relevant in many metabolic processes. For example, enzymes can play a role in digestion in the breakdown of nutrients or also in the activation and degradation of drugs. Each enzyme is responsible for a specific reaction with a defined starting material (substrate). The shape of the substrate must exactly match the respective enzyme so that the reaction can take place (lock-and-key principle). Pharmacogenetics looks at enzymes in drug metabolism. The functionality of these enzymes is based on the composition of the respective gene. Depending on the underlying genetics, the enzymes may accelerate the biochemical reaction more slowly or faster than average. On this basis, it can be determined whether, for example, a lower dose of a drug is required for a patient, as the drug remains in the blood circulation for longer on average due to slower degradation.
Each regular body cell contains twenty-three pairs of chromosomes, twenty-two autosomal pairs, and one pair of sex chromosomes (gonosomes). Normally, we inherit one chromosome from the mother and one from the father from each of these pairs. This means that there is one gene copy (allele) from both parents for each trait. A trait can be inherited either dominantly or recessively. A recessive trait (e.g., blue eye color) must be present twice, i.e. must have been inherited from both parents to prevail. For a dominant trait (e.g., brown eye color), one gene copy is sufficient. In the case of codominant traits, both gene copies are expressed to the same extent. An example of this are the blood group traits A and B. In genetics, a distinction is also made as to whether the inherited trait is present on one of the twenty-two autosomal chromosome pairs or on the sex chromosomes X or Y. This can be relevant, for example, for disease or inheritance probabilities.
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