How genetic inheritance works: basic principles

Mendel's basic principles of genetic inheritance

Mendel's laws are the basic principles that explain genetic inheritance . Although there is no doubt that the discovery of the human genome has provided a wealth of information.

These laws, enumerated by scientist Gregor Mendel in 1865 , are still valid and should be known. Initially, he drew conclusions from observing plants and cross-breeding different varieties. Let's remember that, at that time, genetic studies in humans were very limited due to a lack of analytical methods. For this reason, it is essential to start from the foundation Mendel offers us in his laws, because everything else has been confirmed by further studies.

Now, we must say that these laws apply equally to analyzing plant and animal organisms. And, now that we have the resources, genetic testing sheds light. Take a look at why these reasons are relevant:

1. Principle of uniformity

The first of Mendel's laws responds to the principle of uniformity . That is, if two pure genetic lines are crossed, the succession would be equal at the phenotypic and genotypic levels .

It should be noted that this is important because the offspring will be exactly like one of the parents . Which allele will determine this? Specifically, the dominant allele will determine external appearance. This may be harmless when referring to appearance, but it can have other consequences.

In other words, for a mutation to occur, it would have to be due to a circumstance already present in one of the parents, either the father or the mother. The problem is that this was often not possible to detect at first.

This is evident in plants, but it also applies to human genetic inheritance. For example, in the case of a parent's disease, it's essential to know whether it's dominant or recessive. To know which eye color is most likely to be inherited, it would be good to know the eye color of all four grandparents.

The problem is that pure genetic lines are almost impossible in humans, due to all the diversity inherited over millennia. This concept, which has traditionally been associated with race, is now obsolete.

2. Principle of segregation

The principle of segregation is that alleles at the same locus separate , giving rise to half the gametes with the recessive gene and half with the dominant gene . That is, the separation results in a 50-50 ratio.

Now, this transmission provides variety in the offspring, whether plant or animal. Not surprisingly, it should be noted that the proportion of offspring will be three with the dominant gene and one with the recessive gene . This is especially interesting because this principle minimizes the possibility of problems in the offspring. If the principle of segregation did not exist, the offspring would always be homogeneous.

The truth is that this was once proven in peas. The color was different in certain cases following this principle. However, the fact is that if related varieties are constantly crossed, the recessive gene normally disappears; it's not surprising that it's a crucial element when it comes to improving plant genetics.

3. Principle of independent transmission (genetic inheritance)

Mendel's third law is the so-called principle of independent transmission . This implies that traits inherited from offspring are not necessarily related to each other, as long as there is no direct link between the genes.

The transmission of traits occurs through alleles, taking into account dominant and recessive factors. And, here, these are transmitted independently of those of another gene. Hair color can be passed on to one offspring, but eye color to another, depending on the case. And there's nothing strange about this happening this way; this should reassure the parents, because it's perfectly possible.

We sometimes wonder why one child inherits the same eye and hair color as their father, while another doesn't. The answer lies precisely in the principle of independent transmission. It's even possible for a trait to be inherited from one of the grandparents.

How can I reduce my offspring's risk of developing congenital diseases?

The principles of genetic inheritance allow us to draw two conclusions : first, that there is a certain predisposition to inherit traits (healthy or unhealthy); second, that it is extremely important to know the genetic background of each parent.

Previously, this wasn't possible because the map of the human genome hadn't been fully decoded. And this, obviously, created problems and complications. The analyses were partial and fragmented, so not all the information was available. This has changed substantially today because we have testing and screening methods.

At this point, there are two ways to reduce your chances of passing on genetic inheritance . First, you can take an individual genetic test to find out if you have certain congenital conditions or are predisposed to them. Second, you and your partner can take a genetic compatibility test if you want to conceive. This is always recommended, but especially if you are related.

Ultimately, we're talking about predictive and preventive actions , but they can reduce the likelihood of problems. And, above all, they can make you consider whether natural conception is the best option or whether other alternatives are necessary.

In conclusion

The principles of genetic inheritance allow us to know what to expect in certain contexts. Therefore, it's a good idea to familiarize yourself with these principles and, if you have any questions, take a test. At Genotica , you'll find different tests and price comparisons in your city. Visit the website to learn more and find the test you're looking for!